CA2621974A1 - Starch etherification method - Google Patents
Starch etherification method Download PDFInfo
- Publication number
- CA2621974A1 CA2621974A1 CA002621974A CA2621974A CA2621974A1 CA 2621974 A1 CA2621974 A1 CA 2621974A1 CA 002621974 A CA002621974 A CA 002621974A CA 2621974 A CA2621974 A CA 2621974A CA 2621974 A1 CA2621974 A1 CA 2621974A1
- Authority
- CA
- Canada
- Prior art keywords
- alkyl
- starch
- group
- aryl
- halogen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 229920002472 Starch Polymers 0.000 title claims abstract description 68
- 235000019698 starch Nutrition 0.000 title claims abstract description 67
- 239000008107 starch Substances 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000006266 etherification reaction Methods 0.000 title claims abstract description 14
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims abstract description 44
- 239000002608 ionic liquid Substances 0.000 claims abstract description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 23
- 238000004090 dissolution Methods 0.000 claims abstract description 17
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 125000003118 aryl group Chemical group 0.000 claims description 20
- 229910052736 halogen Inorganic materials 0.000 claims description 18
- 239000002904 solvent Substances 0.000 claims description 18
- 150000002367 halogens Chemical group 0.000 claims description 17
- 125000004169 (C1-C6) alkyl group Chemical group 0.000 claims description 13
- 150000001768 cations Chemical class 0.000 claims description 11
- -1 phosphoro Chemical group 0.000 claims description 11
- 150000001450 anions Chemical class 0.000 claims description 10
- 125000003808 silyl group Chemical group [H][Si]([H])([H])[*] 0.000 claims description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Inorganic materials [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 10
- 125000006273 (C1-C3) alkyl group Chemical group 0.000 claims description 9
- 229910052739 hydrogen Inorganic materials 0.000 claims description 9
- 239000001257 hydrogen Substances 0.000 claims description 9
- 125000003545 alkoxy group Chemical group 0.000 claims description 8
- 125000000020 sulfo group Chemical group O=S(=O)([*])O[H] 0.000 claims description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 7
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 6
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical group NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 claims description 6
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 6
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 6
- 150000007942 carboxylates Chemical class 0.000 claims description 6
- 125000000524 functional group Chemical group 0.000 claims description 6
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 6
- 125000000449 nitro group Chemical group [O-][N+](*)=O 0.000 claims description 6
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims description 6
- 125000002577 pseudohalo group Chemical group 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 5
- 125000004183 alkoxy alkyl group Chemical group 0.000 claims description 5
- 125000000217 alkyl group Chemical group 0.000 claims description 4
- 125000001033 ether group Chemical group 0.000 claims description 4
- 125000000623 heterocyclic group Chemical group 0.000 claims description 4
- 150000007529 inorganic bases Chemical class 0.000 claims description 4
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 claims description 4
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims description 4
- 125000001424 substituent group Chemical group 0.000 claims description 4
- 125000000923 (C1-C30) alkyl group Chemical group 0.000 claims description 3
- 125000004191 (C1-C6) alkoxy group Chemical group 0.000 claims description 3
- 125000002837 carbocyclic group Chemical group 0.000 claims description 3
- 150000001923 cyclic compounds Chemical class 0.000 claims description 3
- 125000006527 (C1-C5) alkyl group Chemical group 0.000 claims description 2
- NOWKCMXCCJGMRR-UHFFFAOYSA-N Aziridine Chemical compound C1CN1 NOWKCMXCCJGMRR-UHFFFAOYSA-N 0.000 claims description 2
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 claims description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical group [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 2
- 150000001408 amides Chemical class 0.000 claims description 2
- 125000003917 carbamoyl group Chemical group [H]N([H])C(*)=O 0.000 claims description 2
- 208000035196 congenital hypomyelinating 2 neuropathy Diseases 0.000 claims description 2
- 125000004093 cyano group Chemical group *C#N 0.000 claims description 2
- 150000002118 epoxides Chemical class 0.000 claims description 2
- 238000000605 extraction Methods 0.000 claims description 2
- 150000002431 hydrogen Chemical class 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 2
- 150000002576 ketones Chemical class 0.000 claims description 2
- 239000010695 polyglycol Substances 0.000 claims description 2
- 229920000151 polyglycol Polymers 0.000 claims description 2
- WMFOQBRAJBCJND-UHFFFAOYSA-M lithium hydroxide Inorganic materials [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims 2
- 125000003158 alcohol group Chemical group 0.000 claims 1
- 229920002678 cellulose Polymers 0.000 abstract description 27
- 239000001913 cellulose Substances 0.000 abstract description 27
- 238000006243 chemical reaction Methods 0.000 description 12
- 150000002170 ethers Chemical class 0.000 description 10
- 239000008187 granular material Substances 0.000 description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 239000003153 chemical reaction reagent Substances 0.000 description 8
- 239000000047 product Substances 0.000 description 8
- 229920000945 Amylopectin Polymers 0.000 description 7
- 229920000856 Amylose Polymers 0.000 description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 6
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 6
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 6
- 229920003086 cellulose ether Polymers 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 150000007530 organic bases Chemical class 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 238000003786 synthesis reaction Methods 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 5
- FHDQNOXQSTVAIC-UHFFFAOYSA-M 1-butyl-3-methylimidazol-3-ium;chloride Chemical compound [Cl-].CCCCN1C=C[N+](C)=C1 FHDQNOXQSTVAIC-UHFFFAOYSA-M 0.000 description 4
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- 125000005843 halogen group Chemical group 0.000 description 4
- 230000001376 precipitating effect Effects 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 3
- QGJOPFRUJISHPQ-UHFFFAOYSA-N Carbon disulfide Chemical compound S=C=S QGJOPFRUJISHPQ-UHFFFAOYSA-N 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 125000001309 chloro group Chemical group Cl* 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 238000001125 extrusion Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 3
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 3
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- GNPSDJOWGWWXSS-UHFFFAOYSA-M 1-benzylpyridin-1-ium;chloride Chemical compound [Cl-].C=1C=CC=C[N+]=1CC1=CC=CC=C1 GNPSDJOWGWWXSS-UHFFFAOYSA-M 0.000 description 2
- DYSTXVCDLKSPAZ-UHFFFAOYSA-N 1h-imidazole;1,3-oxazole;1h-pyrazole Chemical compound C=1C=NNC=1.C1=CNC=N1.C1=COC=N1 DYSTXVCDLKSPAZ-UHFFFAOYSA-N 0.000 description 2
- UFJFDFPKUARWEJ-UHFFFAOYSA-N C1=CN=NN1.C1=CSC=N1.C1=NC=NN1 Chemical compound C1=CN=NN1.C1=CSC=N1.C1=NC=NN1 UFJFDFPKUARWEJ-UHFFFAOYSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- 229920002261 Corn starch Polymers 0.000 description 2
- 229920000875 Dissolving pulp Polymers 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 240000005979 Hordeum vulgare Species 0.000 description 2
- 235000007340 Hordeum vulgare Nutrition 0.000 description 2
- JGFZNNIVVJXRND-UHFFFAOYSA-N N,N-Diisopropylethylamine (DIPEA) Chemical compound CCN(C(C)C)C(C)C JGFZNNIVVJXRND-UHFFFAOYSA-N 0.000 description 2
- 229920000297 Rayon Polymers 0.000 description 2
- ZMZDMBWJUHKJPS-UHFFFAOYSA-M Thiocyanate anion Chemical compound [S-]C#N ZMZDMBWJUHKJPS-UHFFFAOYSA-M 0.000 description 2
- DTQVDTLACAAQTR-UHFFFAOYSA-N Trifluoroacetic acid Chemical compound OC(=O)C(F)(F)F DTQVDTLACAAQTR-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 125000001797 benzyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])([H])* 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- 235000013339 cereals Nutrition 0.000 description 2
- FOCAUTSVDIKZOP-UHFFFAOYSA-N chloroacetic acid Chemical compound OC(=O)CCl FOCAUTSVDIKZOP-UHFFFAOYSA-N 0.000 description 2
- 238000010411 cooking Methods 0.000 description 2
- XLJMAIOERFSOGZ-UHFFFAOYSA-M cyanate Chemical compound [O-]C#N XLJMAIOERFSOGZ-UHFFFAOYSA-M 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 125000001153 fluoro group Chemical group F* 0.000 description 2
- 125000005842 heteroatom Chemical group 0.000 description 2
- 125000004051 hexyl group Chemical class [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 2
- ZMZDMBWJUHKJPS-UHFFFAOYSA-N hydrogen thiocyanate Natural products SC#N ZMZDMBWJUHKJPS-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 125000001147 pentyl group Chemical group C(CCCC)* 0.000 description 2
- 125000000286 phenylethyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])([H])C([H])([H])* 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229920001592 potato starch Polymers 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 238000012552 review Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- ITMCEJHCFYSIIV-UHFFFAOYSA-M triflate Chemical compound [O-]S(=O)(=O)C(F)(F)F ITMCEJHCFYSIIV-UHFFFAOYSA-M 0.000 description 2
- 125000004400 (C1-C12) alkyl group Chemical group 0.000 description 1
- 125000004178 (C1-C4) alkyl group Chemical group 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- FERIUCNNQQJTOY-UHFFFAOYSA-M Butyrate Chemical compound CCCC([O-])=O FERIUCNNQQJTOY-UHFFFAOYSA-M 0.000 description 1
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Natural products CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 125000002353 D-glucosyl group Chemical group C1([C@H](O)[C@@H](O)[C@H](O)[C@H](O1)CO)* 0.000 description 1
- 240000001624 Espostoa lanata Species 0.000 description 1
- 235000009161 Espostoa lanata Nutrition 0.000 description 1
- BDAGIHXWWSANSR-UHFFFAOYSA-M Formate Chemical compound [O-]C=O BDAGIHXWWSANSR-UHFFFAOYSA-M 0.000 description 1
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 1
- 229920001503 Glucan Polymers 0.000 description 1
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 description 1
- RAXXELZNTBOGNW-UHFFFAOYSA-O Imidazolium Chemical compound C1=C[NH+]=CN1 RAXXELZNTBOGNW-UHFFFAOYSA-O 0.000 description 1
- JVTAAEKCZFNVCJ-UHFFFAOYSA-M Lactate Chemical compound CC(O)C([O-])=O JVTAAEKCZFNVCJ-UHFFFAOYSA-M 0.000 description 1
- 229920000433 Lyocell Polymers 0.000 description 1
- 235000019759 Maize starch Nutrition 0.000 description 1
- 240000003183 Manihot esculenta Species 0.000 description 1
- 235000016735 Manihot esculenta subsp esculenta Nutrition 0.000 description 1
- 244000151018 Maranta arundinacea Species 0.000 description 1
- 235000010804 Maranta arundinacea Nutrition 0.000 description 1
- 229920000881 Modified starch Polymers 0.000 description 1
- KWYHDKDOAIKMQN-UHFFFAOYSA-N N,N,N',N'-tetramethylethylenediamine Chemical compound CN(C)CCN(C)C KWYHDKDOAIKMQN-UHFFFAOYSA-N 0.000 description 1
- LFTLOKWAGJYHHR-UHFFFAOYSA-N N-methylmorpholine N-oxide Chemical compound CN1(=O)CCOCC1 LFTLOKWAGJYHHR-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- LCTONWCANYUPML-UHFFFAOYSA-M Pyruvate Chemical compound CC(=O)C([O-])=O LCTONWCANYUPML-UHFFFAOYSA-M 0.000 description 1
- 244000061456 Solanum tuberosum Species 0.000 description 1
- 235000002595 Solanum tuberosum Nutrition 0.000 description 1
- 241000272534 Struthio camelus Species 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical group [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 235000012419 Thalia geniculata Nutrition 0.000 description 1
- 241000209140 Triticum Species 0.000 description 1
- 235000021307 Triticum Nutrition 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 125000003710 aryl alkyl group Chemical group 0.000 description 1
- 125000001246 bromo group Chemical group Br* 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 235000014633 carbohydrates Nutrition 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 229920003064 carboxyethyl cellulose Polymers 0.000 description 1
- 125000002057 carboxymethyl group Chemical group [H]OC(=O)C([H])([H])[*] 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 229940089960 chloroacetate Drugs 0.000 description 1
- 229940106681 chloroacetic acid Drugs 0.000 description 1
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical group Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 239000008120 corn starch Substances 0.000 description 1
- 125000000392 cycloalkenyl group Chemical group 0.000 description 1
- 125000000753 cycloalkyl group Chemical group 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 125000005982 diphenylmethyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])(*)C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000011978 dissolution method Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000032050 esterification Effects 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- ZOOODBUHSVUZEM-UHFFFAOYSA-N ethoxymethanedithioic acid Chemical compound CCOC(S)=S ZOOODBUHSVUZEM-UHFFFAOYSA-N 0.000 description 1
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000013467 fragmentation Methods 0.000 description 1
- 238000006062 fragmentation reaction Methods 0.000 description 1
- 150000004676 glycans Chemical class 0.000 description 1
- 235000019447 hydroxyethyl cellulose Nutrition 0.000 description 1
- 239000001863 hydroxypropyl cellulose Substances 0.000 description 1
- 230000009878 intermolecular interaction Effects 0.000 description 1
- 150000008040 ionic compounds Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- ZSVHUITUMSDFCK-UHFFFAOYSA-N isoquinoline;quinoline Chemical compound C1=NC=CC2=CC=CC=C21.N1=CC=CC2=CC=CC=C21 ZSVHUITUMSDFCK-UHFFFAOYSA-N 0.000 description 1
- 150000002605 large molecules Chemical class 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 235000019426 modified starch Nutrition 0.000 description 1
- 125000001624 naphthyl group Chemical group 0.000 description 1
- 229920005615 natural polymer Polymers 0.000 description 1
- 238000006053 organic reaction Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- AXIPBRXJGSXLHF-UHFFFAOYSA-N piperidine;pyrrolidine Chemical compound C1CCNC1.C1CCNCC1 AXIPBRXJGSXLHF-UHFFFAOYSA-N 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000003586 protic polar solvent Substances 0.000 description 1
- PMYJMININHDGDV-UHFFFAOYSA-N pyrazine;pyridazine;pyridine;pyrimidine Chemical compound C1=CC=NC=C1.C1=CC=NN=C1.C1=CN=CN=C1.C1=CN=CC=N1 PMYJMININHDGDV-UHFFFAOYSA-N 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 239000004627 regenerated cellulose Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 229940100486 rice starch Drugs 0.000 description 1
- 125000002914 sec-butyl group Chemical group [H]C([H])([H])C([H])([H])C([H])(*)C([H])([H])[H] 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005063 solubilization Methods 0.000 description 1
- 230000007928 solubilization Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 229910052717 sulfur Chemical group 0.000 description 1
- 239000011593 sulfur Chemical group 0.000 description 1
- 125000004434 sulfur atom Chemical group 0.000 description 1
- 229920001059 synthetic polymer Polymers 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
- JBWKIWSBJXDJDT-UHFFFAOYSA-N triphenylmethyl chloride Chemical compound C=1C=CC=CC=1C(C=1C=CC=CC=1)(Cl)C1=CC=CC=C1 JBWKIWSBJXDJDT-UHFFFAOYSA-N 0.000 description 1
- 125000002221 trityl group Chemical group [H]C1=C([H])C([H])=C([H])C([H])=C1C([*])(C1=C(C(=C(C(=C1[H])[H])[H])[H])[H])C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 229940100445 wheat starch Drugs 0.000 description 1
- 239000012991 xanthate Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B31/00—Preparation of derivatives of starch
- C08B31/08—Ethers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B11/00—Preparation of cellulose ethers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B31/00—Preparation of derivatives of starch
- C08B31/08—Ethers
- C08B31/12—Ethers having alkyl or cycloalkyl radicals substituted by heteroatoms, e.g. hydroxyalkyl or carboxyalkyl starch
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
- C08L3/02—Starch; Degradation products thereof, e.g. dextrin
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Biochemistry (AREA)
- Materials Engineering (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
Abstract
The invention relates to a method for preparing a starch ether. The method comprises mixing cellulose with an ionic liquid solvent to dissolve the starch, and then treating the dissolved starch with an etherifying agent in the presence of a base to form a starch ether, and subsequently separating the starch ether from the solution, wherein both the dissolution and the etherification are carried out in the substantial absence of water.
Description
Starch etherification method Field of the invention The present invention is directed to a new method for preparing starch ethers.
Background art Unlike other carbohydrates and edible polymers, starch occurs as discrete particles called starch granules. These are generally composed of two type of molecules, amylose and amylopectin. Of these, amylose is a linear (1,4)-a-D-glucan, while amylopectin is a branched, bushlike structure containing both (1,4)-a-D
linkages between D-glucose residues and (1,6)-a-D branch points, Ullmann 's Encyclopedia of Industrial Chemistry, Vol. A25, 1994, p. 1-18. Following formulae depict representative structures of amylose and amylopectin.
O O
OH OH OHO
-O O O O
OH OH OH
Representative structure of linear amylose O O
OH OH
O O O
CHZOH CH2 CHaOH
O O
OH OH
-O O O OHO
O
OH OH OH
Representative structure of amylopectin, including (1,6)-a-branch point Normal starches contain approximately 75% amylopectin molecules the rest consisting of amylose. Amylopectin is a very large molecule with molecular masses ranging from one to several millions. Linearly structured amylose is considerably smaller and the molecular masses usually fall in the range of 5000 - 200000.
Commercial starches are obtained from seeds, particularly corn, wheat, rice, tapioca arrowroot, sago, and potato. Especially in Scandinavia, also barley is utilized as a native starch source. Among these, the starch granules vary in diameter from 1-100 m. Rice starch has the smallest granules (3-9 m), potato starch ranges between 15-100 in and corn starch granules are 5-26 in with an average diameter of 15 in. Additionally, wheat starch granules are typically from 3 to 35 m and corresponding barley starch from 5 to 35 m. Kirk-Othmer, Encyclopedia of Chemical Technology, 1997, 4th edition, Vol. 22, p. 699-719 and Ketola H, Andersson T, Papermaking Chemistr.y, 1999, Book 4, p. 269-274.
Due to their extremely high molecular masses as well as chemical composition consisting of both amylose and especially bushlike amylopectin, these branched polysaccharides are practically insoluble into other solvents than water. And in water, the starch granules must be cooked before they will release their water-soluble molecules. In general, they do not form true solutions in water because of their molecular sizes and intermolecular interactions; rather they form molecular dispersions. Most starch derivatives can be prepared from any native starch but, for reasons of solublity and molecular size, they are mainly produced from potato starch and, in the United States, from waxy maize starch.
Above a certain temperature, characteristic for each type of starch and known as gelatinization temperature, the starch grains burst and form a gel. The viscositity increases to a maximuin, and then decreases asyinptotically to a limiting value as the solubilized polymer molecules in water disperse. Complete solubilization of individual molecules of a starch grain only occurs above 100 C, Ullmann's Encyclopedia of IndustNial Chemistry, Vol. A26, 1995, p. 246-248.
The effect of thermal treatinent on starches depends strongly on whether it occurs in excess water, limited water, under pressure, or in extrusion cooking. In excess water it appears that starch swelling is a two-stage process consisting of initial granule swelling followed then by granule dissolution. Both of these steps are irreversible.
In limited water, thermal responses have been interpreted as being due to starch crystallite melting. When extrusion cooking is applied, starch granules are torn physically apart, allowing thus more rapid penetration of water into the granule. In contrast to normal gelatinization, starch fragmentation (dextrinization) appears to be the predominant reaction during extrusion, Kirk-Othmer, Encyclopedia of Chemical Technology, 1997, 4th edition, Vol. 22, p. 699-719.
Dissolution of starch US 1943 176 discloses a process for the preparation of solutions of cellulose by dissolving cellulose under heating in a liquefied N-alkylpyridinium or N-benzyl-pyridinium chloride salt, preferably in the presence of an anhydrous nitrogen-containing base, such as pyridine. These salts are known as ionic liquids. The cellulose to be dissolved is preferably in the fonn of regenerated cellulose or bleached cellulose or linter. US 1 943 176 also suggests separating cellulose from the cellulose solution by means of suitable precipitating agents, such as water or alcohol to produce for example cellulose threads or films or masses. According to US 1 943 176 the cellulose solutions are suitable for various chemical reactions, such as etherification or esterification. In Exainple 14 triphenylchloromethane is added to a solution of cellulose in a mixture of benzylpyridinium chloride and pyridine, and subsequently the cellulose solution is poured into methylalcohol to separate the cellulose ether.
Also other cellulose solvents are known. For example, viscose rayon is prepared from cellulose xanthate utilizing carbon disulfide as both reagent and solvent.
US 3 447 939 discloses dissolving natural or synthetic polymeric compounds, such as cellulose in a cyclic mono(N-methylamine-N-oxide), especially N-methyl-morpholine-N-oxide.
WO 03/029329 discloses a dissolution method very similar to the one disclosed in US 1 943 176. The main iinproveinent resides in the application of microwave radiation to assist in dissolution. The cellulose to be dissolved is fibrous cellulose, wood pulp, linters, cotton balls or paper, i.e. cellulose in a highly pure form. The inventors of WO 03/029329 have published an article (Swatloski, R.P.; Spear S.K.;
Holbrey, J.D.; Rogers, R.D. Journal of American Chemical Society, 2002, 124, p.
4974-4975) focussed on the dissolution of cellulose with ionic liquids, especially 1-butyl-3-methyl-imidazolium chloride, by heating in a microwave oven. The cellulose used in the dissolution experiments was dissolving pulp (from cellulose acetate, lyocell, and rayon production lines), fibrous cellulose and filter paper, i.e.
cellulose in a highly pure form that does not contain any significant amounts of lignin. This article also teaches precipitating cellulose from the ionic liquid solution by the addition of water or other precipitating solutions including ethanol and acetone.
Background art Unlike other carbohydrates and edible polymers, starch occurs as discrete particles called starch granules. These are generally composed of two type of molecules, amylose and amylopectin. Of these, amylose is a linear (1,4)-a-D-glucan, while amylopectin is a branched, bushlike structure containing both (1,4)-a-D
linkages between D-glucose residues and (1,6)-a-D branch points, Ullmann 's Encyclopedia of Industrial Chemistry, Vol. A25, 1994, p. 1-18. Following formulae depict representative structures of amylose and amylopectin.
O O
OH OH OHO
-O O O O
OH OH OH
Representative structure of linear amylose O O
OH OH
O O O
CHZOH CH2 CHaOH
O O
OH OH
-O O O OHO
O
OH OH OH
Representative structure of amylopectin, including (1,6)-a-branch point Normal starches contain approximately 75% amylopectin molecules the rest consisting of amylose. Amylopectin is a very large molecule with molecular masses ranging from one to several millions. Linearly structured amylose is considerably smaller and the molecular masses usually fall in the range of 5000 - 200000.
Commercial starches are obtained from seeds, particularly corn, wheat, rice, tapioca arrowroot, sago, and potato. Especially in Scandinavia, also barley is utilized as a native starch source. Among these, the starch granules vary in diameter from 1-100 m. Rice starch has the smallest granules (3-9 m), potato starch ranges between 15-100 in and corn starch granules are 5-26 in with an average diameter of 15 in. Additionally, wheat starch granules are typically from 3 to 35 m and corresponding barley starch from 5 to 35 m. Kirk-Othmer, Encyclopedia of Chemical Technology, 1997, 4th edition, Vol. 22, p. 699-719 and Ketola H, Andersson T, Papermaking Chemistr.y, 1999, Book 4, p. 269-274.
Due to their extremely high molecular masses as well as chemical composition consisting of both amylose and especially bushlike amylopectin, these branched polysaccharides are practically insoluble into other solvents than water. And in water, the starch granules must be cooked before they will release their water-soluble molecules. In general, they do not form true solutions in water because of their molecular sizes and intermolecular interactions; rather they form molecular dispersions. Most starch derivatives can be prepared from any native starch but, for reasons of solublity and molecular size, they are mainly produced from potato starch and, in the United States, from waxy maize starch.
Above a certain temperature, characteristic for each type of starch and known as gelatinization temperature, the starch grains burst and form a gel. The viscositity increases to a maximuin, and then decreases asyinptotically to a limiting value as the solubilized polymer molecules in water disperse. Complete solubilization of individual molecules of a starch grain only occurs above 100 C, Ullmann's Encyclopedia of IndustNial Chemistry, Vol. A26, 1995, p. 246-248.
The effect of thermal treatinent on starches depends strongly on whether it occurs in excess water, limited water, under pressure, or in extrusion cooking. In excess water it appears that starch swelling is a two-stage process consisting of initial granule swelling followed then by granule dissolution. Both of these steps are irreversible.
In limited water, thermal responses have been interpreted as being due to starch crystallite melting. When extrusion cooking is applied, starch granules are torn physically apart, allowing thus more rapid penetration of water into the granule. In contrast to normal gelatinization, starch fragmentation (dextrinization) appears to be the predominant reaction during extrusion, Kirk-Othmer, Encyclopedia of Chemical Technology, 1997, 4th edition, Vol. 22, p. 699-719.
Dissolution of starch US 1943 176 discloses a process for the preparation of solutions of cellulose by dissolving cellulose under heating in a liquefied N-alkylpyridinium or N-benzyl-pyridinium chloride salt, preferably in the presence of an anhydrous nitrogen-containing base, such as pyridine. These salts are known as ionic liquids. The cellulose to be dissolved is preferably in the fonn of regenerated cellulose or bleached cellulose or linter. US 1 943 176 also suggests separating cellulose from the cellulose solution by means of suitable precipitating agents, such as water or alcohol to produce for example cellulose threads or films or masses. According to US 1 943 176 the cellulose solutions are suitable for various chemical reactions, such as etherification or esterification. In Exainple 14 triphenylchloromethane is added to a solution of cellulose in a mixture of benzylpyridinium chloride and pyridine, and subsequently the cellulose solution is poured into methylalcohol to separate the cellulose ether.
Also other cellulose solvents are known. For example, viscose rayon is prepared from cellulose xanthate utilizing carbon disulfide as both reagent and solvent.
US 3 447 939 discloses dissolving natural or synthetic polymeric compounds, such as cellulose in a cyclic mono(N-methylamine-N-oxide), especially N-methyl-morpholine-N-oxide.
WO 03/029329 discloses a dissolution method very similar to the one disclosed in US 1 943 176. The main iinproveinent resides in the application of microwave radiation to assist in dissolution. The cellulose to be dissolved is fibrous cellulose, wood pulp, linters, cotton balls or paper, i.e. cellulose in a highly pure form. The inventors of WO 03/029329 have published an article (Swatloski, R.P.; Spear S.K.;
Holbrey, J.D.; Rogers, R.D. Journal of American Chemical Society, 2002, 124, p.
4974-4975) focussed on the dissolution of cellulose with ionic liquids, especially 1-butyl-3-methyl-imidazolium chloride, by heating in a microwave oven. The cellulose used in the dissolution experiments was dissolving pulp (from cellulose acetate, lyocell, and rayon production lines), fibrous cellulose and filter paper, i.e.
cellulose in a highly pure form that does not contain any significant amounts of lignin. This article also teaches precipitating cellulose from the ionic liquid solution by the addition of water or other precipitating solutions including ethanol and acetone.
Ionic liquids The literature knows many synonyms used for ionic liquids. Up to date, "molten salts" is maybe the most broadly applied term for ionic compounds in the liquid state. There is a difference between molten salts and ionic liquids, however.
Ionic liquids are salts that are liquid around room temperature (typically -100 C to 200 C, but this might even exceed 300 C) (Wassercheid, P.; Welton, T., Ionic Liquids in Synthesis 2003, WILEY-VCH, p. 1-6, 41-55 and 68-81). Therefore, the term RTIL
(room temperature ionic liquids) is commonly applied for these solvents.
RTILs are non-flammable, non-volatile and they possess high therinal stabilities.
Typically, these solvents are organic salts or inixtures consisting of at least one organic component. By changing the nature of the ions present in an RTIL, it is possible to change the resulting properties of the RTILs. The lipophilicity of an ionic liquid of a RTIL is easily modified by the degree of cation substitution.
Similarly, the miscibility with water and other protic solvents can be tuned from complete miscibility to almost total immiscibility, by changing the anion substitution.
All these variations in cations and anions can produce a very large range of ionic liquids allowing the fine-tuning for specific applications. Furthennore, the RTILs are relatively cheap and easy to manufacture. They can also be reused after regeneration.
Microwaves It is known from the recent literature concerning organic synthesis that the reaction times of the organic reactions are remarkable reduced when the energy necessary for the occurrence of the reaction is introduced to the system by using microwave irradiation. The commonly used frequency for microwave energy is 2.45 GHz.
There is a wide and continuously increasing literature available in the area of using microwave techniques in organic synthesis. An example of a short sununary article of this topic was published by Mingos in 1994 (D. Michael P. Mingos;
"Microwaves in chemical synthesis" in Chemistry and industry 1. August 1994, pp. 596-599).
Loupy et. al. have recently published a review concerning heterogenous catalysis under microwave irradiation (Loupy, A., Petit, A., Hamelin, J., Texier-Boullet, F., Jachault, P., Mathe, D.; "New solvent-free organic synthesis using focused microwave" in Synthesis 1998, pp. 1213-1234). Another representative article of the area is published by Strauss as an invited review article (C.R. Strauss;
"A
combinatorial approach to the development of Environmentaly Benign Organic Chemical Preparations", Aust. J Chem. 1999, 52, p. 83-96).
Because of their ionic nature, ionic liquids are excellent media for utilizing microwave techniques. Rogers et al. published in 2002 a method for dissolution of 5 pure cellulose fibers into ionic liquids in the microwave field (Swatloski, R.P.;
Spear S.K.; Holbrey, J.D.; Rogers, R.D. Journal of Arnerican Chemical Society, 2002, 124, p. 4974-4975). Furthennore, they were able to precipitate the fibers back by mixing this fiber-containing solution with water.
Summary of the invention It is an object of this invention to provide a method for preparing starch ethers.
The invention is based on the surprising discovery that alkaline etherification of starch can be conducted in an ionic liquid wherein the reaction between cellulose and the etherifying agent, such as chloroacetic acid/ alkali metal chloroacetate proceeded fast and smoothly and no solubility problems of reagents or the product fonned were detected. The good solubility of reagents accomplishes efficient and economic reactions without any unnecessary excess of the inorganic base, such as NaOH, thus preventing also the cellulose chain degradation. The possibility for the severe degradation is further diminished by the mild reaction conditions and low reaction teinperatures achieved either by microwave irradiation or by pressure.
Due to good solubility of all the starting materials, the invention also accomplishes the possibility to easily control the DS via the reagent to AGU [anhydro-glucopyranose unit(s)] molar ratio. The invention also accomplishes the possibility to prepare highly or fully substituted cellulose ethers and due to better solubility, mild conditions and shorter reaction times, also a method to produce completely new kind of cellulose ethers. The ionic liquids can be reused after regeneration.
Brief description of the drawings In the enclosed drawing Fig. 1 shows a spectrum obtained by FTIR analysis of a carboxymethyl starch sample prepared by the method of the present invention.
Detailed description of the invention According to the invention there is provided a method for preparing a starch ether coinprising inixing starch with an ionic liquid solvent to dissolve the starch, and then treating the dissolved starch with an etherifying agent in the presence of a base to form a starch ether, and subsequently separating the starch ether from the solution, wherein both the dissolution and the etherification are carried out in the substantial absence of water.
The dissolution and etherification can be assisted by applying microwave irradiation and/or pressure.
The pressure is preferably at most 2.0 MPa and inore preferably between 1.5 MPa and 2.0 MPa.
The dissolution of the starch can be carried out at a temperature between 0 C
and 150 C, preferably at a temperature between 10 C and 100 C, such as between 20 C
and 85 C. If microwave irradiation is applied, the heating can be carried out be means of this irradiation. The solution is agitated until coinplete dissolution is obtained.
In the dissolution, no auxiliary organic solvents or co-solvents, such as nitrogen-containing bases, e.g. pyridine, are necessary. Organic bases are excluded in this manner.
The dissolution and the etherification are carried out in the substantial absence of water. The phrase "in the substantial absence of water" means that not more than a few percent by weight of water is present. Preferably, the water content is less than 1 percent by weight.
The starch can be present in the solution in an ainount of about 1% to about 35% by weight of the solution. Preferably the amount is from about 10% to about 25%
by weight.
The etherification can be carried out at the same temperature as the dissolution or at a lower temperature. Both inorganic and organic base can be applied as catalysts.
The ionic liquid solvent is molten at a temperature between -100 C and 200 C, preferably at a temperarure of below 170 C, and more preferably between -50 C
and 120 C.
The cation of the ionic liquid solvent in preferably a five- or six-membered heterocylic ring optionally being fused with a benzene ring and comprising as heteroatoms one or more nitrogen, oxygen or sulfur atoms. The heterocyclic ring can be aromatic or saturated. The cation can be one of the following:
Ionic liquids are salts that are liquid around room temperature (typically -100 C to 200 C, but this might even exceed 300 C) (Wassercheid, P.; Welton, T., Ionic Liquids in Synthesis 2003, WILEY-VCH, p. 1-6, 41-55 and 68-81). Therefore, the term RTIL
(room temperature ionic liquids) is commonly applied for these solvents.
RTILs are non-flammable, non-volatile and they possess high therinal stabilities.
Typically, these solvents are organic salts or inixtures consisting of at least one organic component. By changing the nature of the ions present in an RTIL, it is possible to change the resulting properties of the RTILs. The lipophilicity of an ionic liquid of a RTIL is easily modified by the degree of cation substitution.
Similarly, the miscibility with water and other protic solvents can be tuned from complete miscibility to almost total immiscibility, by changing the anion substitution.
All these variations in cations and anions can produce a very large range of ionic liquids allowing the fine-tuning for specific applications. Furthennore, the RTILs are relatively cheap and easy to manufacture. They can also be reused after regeneration.
Microwaves It is known from the recent literature concerning organic synthesis that the reaction times of the organic reactions are remarkable reduced when the energy necessary for the occurrence of the reaction is introduced to the system by using microwave irradiation. The commonly used frequency for microwave energy is 2.45 GHz.
There is a wide and continuously increasing literature available in the area of using microwave techniques in organic synthesis. An example of a short sununary article of this topic was published by Mingos in 1994 (D. Michael P. Mingos;
"Microwaves in chemical synthesis" in Chemistry and industry 1. August 1994, pp. 596-599).
Loupy et. al. have recently published a review concerning heterogenous catalysis under microwave irradiation (Loupy, A., Petit, A., Hamelin, J., Texier-Boullet, F., Jachault, P., Mathe, D.; "New solvent-free organic synthesis using focused microwave" in Synthesis 1998, pp. 1213-1234). Another representative article of the area is published by Strauss as an invited review article (C.R. Strauss;
"A
combinatorial approach to the development of Environmentaly Benign Organic Chemical Preparations", Aust. J Chem. 1999, 52, p. 83-96).
Because of their ionic nature, ionic liquids are excellent media for utilizing microwave techniques. Rogers et al. published in 2002 a method for dissolution of 5 pure cellulose fibers into ionic liquids in the microwave field (Swatloski, R.P.;
Spear S.K.; Holbrey, J.D.; Rogers, R.D. Journal of Arnerican Chemical Society, 2002, 124, p. 4974-4975). Furthennore, they were able to precipitate the fibers back by mixing this fiber-containing solution with water.
Summary of the invention It is an object of this invention to provide a method for preparing starch ethers.
The invention is based on the surprising discovery that alkaline etherification of starch can be conducted in an ionic liquid wherein the reaction between cellulose and the etherifying agent, such as chloroacetic acid/ alkali metal chloroacetate proceeded fast and smoothly and no solubility problems of reagents or the product fonned were detected. The good solubility of reagents accomplishes efficient and economic reactions without any unnecessary excess of the inorganic base, such as NaOH, thus preventing also the cellulose chain degradation. The possibility for the severe degradation is further diminished by the mild reaction conditions and low reaction teinperatures achieved either by microwave irradiation or by pressure.
Due to good solubility of all the starting materials, the invention also accomplishes the possibility to easily control the DS via the reagent to AGU [anhydro-glucopyranose unit(s)] molar ratio. The invention also accomplishes the possibility to prepare highly or fully substituted cellulose ethers and due to better solubility, mild conditions and shorter reaction times, also a method to produce completely new kind of cellulose ethers. The ionic liquids can be reused after regeneration.
Brief description of the drawings In the enclosed drawing Fig. 1 shows a spectrum obtained by FTIR analysis of a carboxymethyl starch sample prepared by the method of the present invention.
Detailed description of the invention According to the invention there is provided a method for preparing a starch ether coinprising inixing starch with an ionic liquid solvent to dissolve the starch, and then treating the dissolved starch with an etherifying agent in the presence of a base to form a starch ether, and subsequently separating the starch ether from the solution, wherein both the dissolution and the etherification are carried out in the substantial absence of water.
The dissolution and etherification can be assisted by applying microwave irradiation and/or pressure.
The pressure is preferably at most 2.0 MPa and inore preferably between 1.5 MPa and 2.0 MPa.
The dissolution of the starch can be carried out at a temperature between 0 C
and 150 C, preferably at a temperature between 10 C and 100 C, such as between 20 C
and 85 C. If microwave irradiation is applied, the heating can be carried out be means of this irradiation. The solution is agitated until coinplete dissolution is obtained.
In the dissolution, no auxiliary organic solvents or co-solvents, such as nitrogen-containing bases, e.g. pyridine, are necessary. Organic bases are excluded in this manner.
The dissolution and the etherification are carried out in the substantial absence of water. The phrase "in the substantial absence of water" means that not more than a few percent by weight of water is present. Preferably, the water content is less than 1 percent by weight.
The starch can be present in the solution in an ainount of about 1% to about 35% by weight of the solution. Preferably the amount is from about 10% to about 25%
by weight.
The etherification can be carried out at the same temperature as the dissolution or at a lower temperature. Both inorganic and organic base can be applied as catalysts.
The ionic liquid solvent is molten at a temperature between -100 C and 200 C, preferably at a temperarure of below 170 C, and more preferably between -50 C
and 120 C.
The cation of the ionic liquid solvent in preferably a five- or six-membered heterocylic ring optionally being fused with a benzene ring and comprising as heteroatoms one or more nitrogen, oxygen or sulfur atoms. The heterocyclic ring can be aromatic or saturated. The cation can be one of the following:
Rq R4 R4 R3 R5 R3 R5 R3 R3 N Rq N
R7 O Rs Rs ON Rs N~~ R5 Rs ONK Rs R' R' R1 R~
Pyridinium Pyridazinium Pyrimidinium Pyrazinium Rq R5 R3 Rq R5 R3 Rl ~N(~DhN ,R2 RZ N'0 R5 R" N~JO
R Rl R"
Imidazolium Pyrazolium Oxazolium Rq R3 Rq R3 R3 R2 Rs~/R3 ~ ~~
R~.N,~,N.Ra R~N,N N R~.~O~Rq R NU5 1,2,3-Triazolium 1,2,4-Triazolium Thiazolium Rs R3 R5 R9 R7 N R9 Rs N,Rl R8 Rl R7 R8 Quinolinium Isoquinolinium R~ .N, R6 Rs R3 R~+ RZ
Piperidinium Pyrrolidinium wherein R' and R2 are independently a C1-C6 alkyl or C2-C6 alkoxyalkyl group, and R3, R4, R5, R6, R7, R8 and R9 are independently hydrogen, a C1-C6 alkyl, C2-C6 alkoxyalkyl or C1-C6 alkoxy group or halogen.
In the above fornlulae R' and R2 are preferably both C1-C4 alkyl, and R3-R9, when present, are preferably hydrogen.
C1-C6 alkyl includes methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, tert-butyl, pentyl, the isomers of pentyl, hexyl and the isomers of hexyl.
C1-C6 alkoxy contains the above C1-C6 alkyl bonded to an oxygen atom.
C2-C6 alkoxyalkyl is an alkyl group substituted by an alkoxy group, the total number of carbon atoms being from two to six.
Halogen is preferably chloro, bromo or fluoro, especially chloro.
Preferred cations have following formulae:
R7 O Rs Rs ON Rs N~~ R5 Rs ONK Rs R' R' R1 R~
Pyridinium Pyridazinium Pyrimidinium Pyrazinium Rq R5 R3 Rq R5 R3 Rl ~N(~DhN ,R2 RZ N'0 R5 R" N~JO
R Rl R"
Imidazolium Pyrazolium Oxazolium Rq R3 Rq R3 R3 R2 Rs~/R3 ~ ~~
R~.N,~,N.Ra R~N,N N R~.~O~Rq R NU5 1,2,3-Triazolium 1,2,4-Triazolium Thiazolium Rs R3 R5 R9 R7 N R9 Rs N,Rl R8 Rl R7 R8 Quinolinium Isoquinolinium R~ .N, R6 Rs R3 R~+ RZ
Piperidinium Pyrrolidinium wherein R' and R2 are independently a C1-C6 alkyl or C2-C6 alkoxyalkyl group, and R3, R4, R5, R6, R7, R8 and R9 are independently hydrogen, a C1-C6 alkyl, C2-C6 alkoxyalkyl or C1-C6 alkoxy group or halogen.
In the above fornlulae R' and R2 are preferably both C1-C4 alkyl, and R3-R9, when present, are preferably hydrogen.
C1-C6 alkyl includes methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, tert-butyl, pentyl, the isomers of pentyl, hexyl and the isomers of hexyl.
C1-C6 alkoxy contains the above C1-C6 alkyl bonded to an oxygen atom.
C2-C6 alkoxyalkyl is an alkyl group substituted by an alkoxy group, the total number of carbon atoms being from two to six.
Halogen is preferably chloro, bromo or fluoro, especially chloro.
Preferred cations have following formulae:
,=N'- i~~ 2 R2.N0 5 R1=NUO
R
Imidazolium Pyrazolium Oxazolium R4 R3 R4 R3 R3 R2 R5~ R3 ,~
~v''~
~.N,ON. 2 ~.N + R~=~D~R4 R1 R N R R N N
1,2,3-Triazolium 1,2,4-Triazolium Thiazolium wherein R1-R5 are as defined above.
An especially preferred cation is the imidazolium cation having the formula:
1~' 2 R Y R
wherein R1-R5 are as defined above. In this fonnula R3-R5 are preferably each hydrogen and R' and R2 are independently C1-C6 alkyl or C2-C6 alkoxyalkyl.
More preferably one of R' and R2 is methyl and the other is C1-C6 alkyl. In this formula R3 can also be halogen, preferably chloro.
The anion of the ionic liquid solvent can be one of the following:
halogen such as chloride, bromide or iodide;
pseudohalogen such as thiocyanate or cyanate;
perchlorate;
C1-C6 carboxylate such as formate, acetate, propionate, butyrate, lactate, pyruvate, maleate, fumarate or oxalate;
nitrate;
C2-C6 carboxylate substituted by one or more halogen atoms such as trifluoroacetic acid;
C1-C6 alkyl sulfonate substituted by one or more halogen atoms such as trifluoromethane sulfonate (triflate);
R
Imidazolium Pyrazolium Oxazolium R4 R3 R4 R3 R3 R2 R5~ R3 ,~
~v''~
~.N,ON. 2 ~.N + R~=~D~R4 R1 R N R R N N
1,2,3-Triazolium 1,2,4-Triazolium Thiazolium wherein R1-R5 are as defined above.
An especially preferred cation is the imidazolium cation having the formula:
1~' 2 R Y R
wherein R1-R5 are as defined above. In this fonnula R3-R5 are preferably each hydrogen and R' and R2 are independently C1-C6 alkyl or C2-C6 alkoxyalkyl.
More preferably one of R' and R2 is methyl and the other is C1-C6 alkyl. In this formula R3 can also be halogen, preferably chloro.
The anion of the ionic liquid solvent can be one of the following:
halogen such as chloride, bromide or iodide;
pseudohalogen such as thiocyanate or cyanate;
perchlorate;
C1-C6 carboxylate such as formate, acetate, propionate, butyrate, lactate, pyruvate, maleate, fumarate or oxalate;
nitrate;
C2-C6 carboxylate substituted by one or more halogen atoms such as trifluoroacetic acid;
C1-C6 alkyl sulfonate substituted by one or more halogen atoms such as trifluoromethane sulfonate (triflate);
tetrafluoroborate BF4 ; or phosphorus hexafluoride PF6-.
The above halogen substituents are preferably fluoro.
The anion of the ionic liquid solvent is preferably selected among those providing a hydrophilic ionic liquid solvent. Such anions include halogen, pseudohalogen or C1-C6 carboxylate. The halogen is preferably chloride, bromide or iodide, and the pseudohalogen is preferably thiocyanate or cyanate.
If the cation is a 1-(C1-C6-alkyl)-3-methyl-imidazolium, the anion is preferably a halogenid, especially chloride.
A preferred ionic liquid solvent is 1-butyl-3-methyl-imidazolium chloride (BMIMCI) having a melting point of about 60 C.
Another type of ionic liquid solvents useful in the present invention is an ionic liquid solvent wherein the cation is a quaternary ammonium salt having the formula R1o_N+ R12 wherein Rlo, R", R12 and R13 are independently a C1-C30 alkyl, C3-C8 carbocyclic or C3-C8 heterocyclic group, and the anion is halogen, pseudohalogen, perchlorate, Cl-C6 carboxylate or hydroxide.
The C1-C30 alkyl group can be linear or branched and is preferably a C1-C12 alkyl group.
The C3-C8 carbocyclic group includes cycloalkyl, cycloalkenyl, phenyl, benzyl and phenylethyl groups.
The C3-C8 heterocyclic group can be aromatic or saturated and contains one or more heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur.
The inorganic base used in the etherification is preferably an alkali metal hydroxide such as litium, sodium or potassium hydroxide. Typical organic bases include such basic catalysts as TEA (triethylamine), DIPEA (di-isopropylethyleainine), TMEDA
(N, N, N', N')-tetramethylethylenedianamine etc. The other organic bases are not omitted. Typically, organic bases are rather expensive reagents. Thus, organic bases are employed as catalysts and in catalytic volumes, i.e. they are not employed in equimolar or excess volumes.
The ether group of the starch ethers prepared by the method of the present invention can be a C1-C6 alkyl, aryl or aryl C1-C3 alkyl group optionally substituted by one or 5 more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl.
The ether group of the starch ethers prepared by the method of the present invention can also be a silyl group substituted by three similar or different groups selected from the group consisting of C1-C9 alkyl, aryl and aryl C1-C3 alkyl.
The above halogen substituents are preferably fluoro.
The anion of the ionic liquid solvent is preferably selected among those providing a hydrophilic ionic liquid solvent. Such anions include halogen, pseudohalogen or C1-C6 carboxylate. The halogen is preferably chloride, bromide or iodide, and the pseudohalogen is preferably thiocyanate or cyanate.
If the cation is a 1-(C1-C6-alkyl)-3-methyl-imidazolium, the anion is preferably a halogenid, especially chloride.
A preferred ionic liquid solvent is 1-butyl-3-methyl-imidazolium chloride (BMIMCI) having a melting point of about 60 C.
Another type of ionic liquid solvents useful in the present invention is an ionic liquid solvent wherein the cation is a quaternary ammonium salt having the formula R1o_N+ R12 wherein Rlo, R", R12 and R13 are independently a C1-C30 alkyl, C3-C8 carbocyclic or C3-C8 heterocyclic group, and the anion is halogen, pseudohalogen, perchlorate, Cl-C6 carboxylate or hydroxide.
The C1-C30 alkyl group can be linear or branched and is preferably a C1-C12 alkyl group.
The C3-C8 carbocyclic group includes cycloalkyl, cycloalkenyl, phenyl, benzyl and phenylethyl groups.
The C3-C8 heterocyclic group can be aromatic or saturated and contains one or more heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur.
The inorganic base used in the etherification is preferably an alkali metal hydroxide such as litium, sodium or potassium hydroxide. Typical organic bases include such basic catalysts as TEA (triethylamine), DIPEA (di-isopropylethyleainine), TMEDA
(N, N, N', N')-tetramethylethylenedianamine etc. The other organic bases are not omitted. Typically, organic bases are rather expensive reagents. Thus, organic bases are employed as catalysts and in catalytic volumes, i.e. they are not employed in equimolar or excess volumes.
The ether group of the starch ethers prepared by the method of the present invention can be a C1-C6 alkyl, aryl or aryl C1-C3 alkyl group optionally substituted by one or 5 more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl.
The ether group of the starch ethers prepared by the method of the present invention can also be a silyl group substituted by three similar or different groups selected from the group consisting of C1-C9 alkyl, aryl and aryl C1-C3 alkyl.
10 The aryl group includes phenyl and naphthyl.
The aryl C1-C3 alkyl group (also called aralkyl) is an aryl group as defined above bond to the 0 group of the cellulose by means of an alkyl group containing 1, 2 or 3 carbon atoms. The aryl C1-C3 alkyl group includes for example benzyl, diphenylmethyl, trityl and phenylethyl.
Typical cellulose ethers prepared by the method of the present invention include:
- alkylated sta - 2-hydroxyethylcellulose, 2-hydroxypropylcellulose and 2-butylethylcellulose - 2-aminoethylcellulose - 2-cyanoethylcellulose - carboxymethylcellulose, 2-carboxyethylcellulose and dicarboxymethylcellulose - 2-sulfoethylcellulose - 2-phosphoromethylcellulose.
Typical cellulose silyl ethers prepared by the method of the present invention include: trimethylsilylcellulose, tert-butyldimethylsilylcellulose, diphenylmethyl-silylcellulose, triphenylsilylcellulose, tribenzylsilylcellulose, thexyl-dimethylsilyl-cellulose and triisopropylsilylcellulose.
According to the present invention the cellulose ethers can be prepared by any of following four reactions (Cell-OH stands for cellulose):
The aryl C1-C3 alkyl group (also called aralkyl) is an aryl group as defined above bond to the 0 group of the cellulose by means of an alkyl group containing 1, 2 or 3 carbon atoms. The aryl C1-C3 alkyl group includes for example benzyl, diphenylmethyl, trityl and phenylethyl.
Typical cellulose ethers prepared by the method of the present invention include:
- alkylated sta - 2-hydroxyethylcellulose, 2-hydroxypropylcellulose and 2-butylethylcellulose - 2-aminoethylcellulose - 2-cyanoethylcellulose - carboxymethylcellulose, 2-carboxyethylcellulose and dicarboxymethylcellulose - 2-sulfoethylcellulose - 2-phosphoromethylcellulose.
Typical cellulose silyl ethers prepared by the method of the present invention include: trimethylsilylcellulose, tert-butyldimethylsilylcellulose, diphenylmethyl-silylcellulose, triphenylsilylcellulose, tribenzylsilylcellulose, thexyl-dimethylsilyl-cellulose and triisopropylsilylcellulose.
According to the present invention the cellulose ethers can be prepared by any of following four reactions (Cell-OH stands for cellulose):
a) Starch-OH + Ra-X+ MOH Starch-O-Ra Rc b) Starch-OH + \7-Rb + MOH
Z
Rc I
Starch-O-CH-CH-Rb I
ZH
Rd I
c) Starch-OH + Rd-CH=C(Y)Re + MOH 0 Starch-O-CH-CH-Y
Re d) Starch-OH + Rt-CHN2 + MOH 10 Starch-O-CH2Rf In the above reaction schemes:
M is Li, Na or K, X is halogen, such as chloride, bromide or iodide, or sulfate, Ra is C1-C6 alkyl, aryl or aryl C1-C3 alkyl, said alkyl or aryl optionally being substituted by one or more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl, Ra can also be silyl substituted by three groups selected from the group consisting of C1-C9 alkyl, aryl and aryl C1-C3 alkyl, Z is O(the cyclic compound being an epoxide) or NH (the cyclic coinpound being an aziridine), Rb and Rc are independently hydrogen or C1-C3 alkyl optionally substituted by one or more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl, Y is an electron-attracting substituent, such as cyano (CN), amide (CONH2) or sulfo (SO3-Na+), Rd and Re are independently hydrogen or C1-C3 alkyl, and Rf is C1-C5 alkyl.
The aryl and aryl C1-C3 alkyl groups are as defined above.
The alkoxy group is preferably C1-C6 alkyl-O-.
When preparing starch silyl ethers the reactant Ra-X is preferably a silyl chloride.
According to the present invention both single-substituted starch ethers having only one kind of substituent, and mixed cellulose ethers having two or more different substituents can be prepared.
After the etherification the obtained starch ether can be separated from the solution by adding a non-solvent for the starch ether to precipitate the starch ether.
The non-solvent should also be a non-solvent for the ionic liquid solvent and miscible with the ionic liquid solvent. Said non-solvent is preferably an alcohol, such as a alkanol, for example methanol, ethanol, propanol or isopropanol. Also other non-solvents, such as ketones (e.g. acetone), acetonitrile, dichloromethane, polyglycols and ethers can be used. With appropriate DS of the starch ether, even water can be employed as a non-solvent.
It is also possible to separate the obtained starch ether by extraction with a suitable solvent that is a non-solvent for the ionic liquid solvent.
The main advantages of preferred methods of the present invention for the preparation of starch ethers in ionic liquids are as follows:
= excellent solubility of the reagents used = due to good solubility, possibility to employ all native starches in derivative prepararation = excess of reagents, which in turn would result in starch chain degradation, is avoided = fast and economical preparation of starch ethers = fast and economical separation of reaction products by precipitating the prepared product by adding a non-solvent for the product, and further, a simple, energy efficient drying procedure of the products = preparation of existing and also new starch ether products = dramatically shorter reaction times and lower reaction temperatures by use of microwave irradiation and/or pressure = mild reaction conditions = easy control of the degree of substitution (DS) via the molar ratio of reagent to anhydroglucopyranose unit(s) (AGU) = possibility to prepare highly or fully substituted (DS = 3) starch ethers = possibility to prepare mixed ethers = possibility to reuse the ionic liquids The percentages in this specification refer to % by weight unless otherwise specified.
Example Carboxymethylation of starch 500 mg of starch was dissolved into an ionic liquid (BMIMCI, 5g, melting point 60 C) with the aid of microwaves, resulting in 10% solution. Addition of monochloroacetic acid (2.05 eqv.) was followed by addition of slight excess of solid NaOH (3.25 eqv.). The reaction was conducted at 70 C for two hours, the product being subsequently precipitated by adding isopropanol into the reaction mixture.
The precipitate was filtered off and the by-product salts were removed by washing the precipitate with isopropanol. The washed product carboxymethylated starch was dried overnight in oven at 105 C and analysed with FTIR. The obtained spectrum for carboxymethylcellulose is shown in Fig. 1 [1630 cm-1 vas(COO-), 1424 cm-1 vs (COO-)]. The product dissolves readily in water.
Z
Rc I
Starch-O-CH-CH-Rb I
ZH
Rd I
c) Starch-OH + Rd-CH=C(Y)Re + MOH 0 Starch-O-CH-CH-Y
Re d) Starch-OH + Rt-CHN2 + MOH 10 Starch-O-CH2Rf In the above reaction schemes:
M is Li, Na or K, X is halogen, such as chloride, bromide or iodide, or sulfate, Ra is C1-C6 alkyl, aryl or aryl C1-C3 alkyl, said alkyl or aryl optionally being substituted by one or more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl, Ra can also be silyl substituted by three groups selected from the group consisting of C1-C9 alkyl, aryl and aryl C1-C3 alkyl, Z is O(the cyclic compound being an epoxide) or NH (the cyclic coinpound being an aziridine), Rb and Rc are independently hydrogen or C1-C3 alkyl optionally substituted by one or more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl, Y is an electron-attracting substituent, such as cyano (CN), amide (CONH2) or sulfo (SO3-Na+), Rd and Re are independently hydrogen or C1-C3 alkyl, and Rf is C1-C5 alkyl.
The aryl and aryl C1-C3 alkyl groups are as defined above.
The alkoxy group is preferably C1-C6 alkyl-O-.
When preparing starch silyl ethers the reactant Ra-X is preferably a silyl chloride.
According to the present invention both single-substituted starch ethers having only one kind of substituent, and mixed cellulose ethers having two or more different substituents can be prepared.
After the etherification the obtained starch ether can be separated from the solution by adding a non-solvent for the starch ether to precipitate the starch ether.
The non-solvent should also be a non-solvent for the ionic liquid solvent and miscible with the ionic liquid solvent. Said non-solvent is preferably an alcohol, such as a alkanol, for example methanol, ethanol, propanol or isopropanol. Also other non-solvents, such as ketones (e.g. acetone), acetonitrile, dichloromethane, polyglycols and ethers can be used. With appropriate DS of the starch ether, even water can be employed as a non-solvent.
It is also possible to separate the obtained starch ether by extraction with a suitable solvent that is a non-solvent for the ionic liquid solvent.
The main advantages of preferred methods of the present invention for the preparation of starch ethers in ionic liquids are as follows:
= excellent solubility of the reagents used = due to good solubility, possibility to employ all native starches in derivative prepararation = excess of reagents, which in turn would result in starch chain degradation, is avoided = fast and economical preparation of starch ethers = fast and economical separation of reaction products by precipitating the prepared product by adding a non-solvent for the product, and further, a simple, energy efficient drying procedure of the products = preparation of existing and also new starch ether products = dramatically shorter reaction times and lower reaction temperatures by use of microwave irradiation and/or pressure = mild reaction conditions = easy control of the degree of substitution (DS) via the molar ratio of reagent to anhydroglucopyranose unit(s) (AGU) = possibility to prepare highly or fully substituted (DS = 3) starch ethers = possibility to prepare mixed ethers = possibility to reuse the ionic liquids The percentages in this specification refer to % by weight unless otherwise specified.
Example Carboxymethylation of starch 500 mg of starch was dissolved into an ionic liquid (BMIMCI, 5g, melting point 60 C) with the aid of microwaves, resulting in 10% solution. Addition of monochloroacetic acid (2.05 eqv.) was followed by addition of slight excess of solid NaOH (3.25 eqv.). The reaction was conducted at 70 C for two hours, the product being subsequently precipitated by adding isopropanol into the reaction mixture.
The precipitate was filtered off and the by-product salts were removed by washing the precipitate with isopropanol. The washed product carboxymethylated starch was dried overnight in oven at 105 C and analysed with FTIR. The obtained spectrum for carboxymethylcellulose is shown in Fig. 1 [1630 cm-1 vas(COO-), 1424 cm-1 vs (COO-)]. The product dissolves readily in water.
Claims (17)
1. A method for preparing a starch ether comprising mixing starch with an ionic liquid solvent to dissolve the starch, and then treating the dissolved starch with an etherifying agent in the presence of a base to form a starch ether, and subsequently separating the starch ether from the solution, wherein both the dissolution and the etherification are carried out in the substantial absence of water.
2. A method according to claim 1 wherein the etherifying agent is R a-X, and wherein R a is C1-C6 alkyl, aryl or aryl C1-C3 alkyl, said alkyl or aryl optionally being substituted by one or more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl, R a can also be silyl substituted by three groups selected from the group consisting of C1-C9 alkyl, aryl and aryl C1-C3 alkyl.
3. A method according to claim 1 wherein the etherifying agent is and wherein Z is O (the cyclic compound being an epoxide) or NH (the cyclic compound being an aziridine); and R b and R c are independently hydrogen or C1-C3 alkyl optionally substituted by one or more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl.
4. A method according to claim 1 wherein the etherifying agent is R d-CH=C(Y)R e and wherein Y is an electron-attracting substituent, such as cyano (CN), amide (CONH2) or sulfo (SO3-Na+); and R d and R e are independently hydrogen or C1-C3 alkyl.
5. A method according to claim 1 wherein the etherifying agent is R f-CHN2, and wherein R f is C1-C5 alkyl.
6. A method according to claim 1 wherein microwave irradiation is applied to assist in dissolution and etherification.
7. A method according to claim 1 or 6 wherein pressure is applied to assist in dissolution and etherification.
8. A method according to claim 1 wherein the ionic liquid solvent is molten at a temperature of below 200°C.
9. A method according to claim 1 wherein the cation of the ionic liquid solvent is selected from the group consisting of wherein R1 and R2 are independently a C1-C6 alkyl or C2-C6 alkoxyalkyl group, and R3, R4, R5, R6, R7 , R8 and R9 are independently hydrogen, a C1-C6 alkyl, C2-alkoxyalkyl or C1-C6 alkoxy group or halogen, and wherein the anion of the ionic liquid solvent is halogen, pseudohalogen, perchlorate or C1-C6 carboxylate.
10. A method according to claim 9 wherein said cation comprises wherein R3-R5 are each hydrogen and R1 and R2 are the same or different and represent C1 -C6 alkyl, and said anion is halogen, preferably chloride.
11. A method according to claim 1 wherein the cation of the ionic liquid solvent is wherein R10, R11, R12 and R13 are independently a C1-C30 alkyl, C3-C8 carbocyclic or C3-C8 heterocyclic group and the anion of the ionic liquid solvent is halogen, pseudohalogen, perchlorate, C1-C6 carboxylate or hydroxide.
12. A method according to claim 1 wherein the inorganic base is lithium, sodium or potassium hydroxide.
13. A method according to any of the above claims wherein the ether group of the starch ether is a C1-C6 alkyl, aryl or aryl C1-C3 alkyl group optionally substituted by one or more functional groups selected from the group consisting of carboxyl, hydroxyl, amino, alkoxy, halogen, cyano, amide, sulfo, phosphoro, nitro and silyl.
14. A method according to any of claims 1 to 12 wherein the ether group of the starch ether is a silyl group substituted by three groups selected from the group consisting of C1-C9 alkyl, aryl and aryl C1-C3 alkyl.
15. A method according to claim 1 wherein the starch ether is separated from the solution by adding a non-solvent for the starch ether to precipitate the starch ether.
16. A method according to claim 15 wherein said non-solvent is an alcohol, a ketone, acetonitrile, dichloromethane, a polyglycol, an ether or water.
17. A method according to claim 1 wherein the starch ether is separated by extraction with a non-solvent for the ionic liquid solvent.
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FI20050752A FI120265B (en) | 2005-07-14 | 2005-07-14 | Starch etherification method |
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DE102009012161B8 (en) | 2009-03-06 | 2012-12-13 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Process for the preparation of polysaccharide derivatives |
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