CA1182467A - Process for the preparation of n-monosubstituted o- alkylurethanes - Google Patents

Abstract

PROCESS FOR THE PREPARATION OF
N-MONOSUBSTITUTED O-ALKYLURETHANES

ABSTRACT OF THE DISCLOSURE
N-monosubstituted O-alkylurethanes are prepared by reacting a primary amine with an N,N'-diarylurea, preferably diphenylurea and a primary or secondary alcohol at a temperature from 150 to 300°C. The reactant alcohol has a boiling point which is at least 5°C higher at atmospheric pressure than the aromatic amine from which the urea is derived. The aromatic monoamine on which the urea is based which forms during the reaction is removed by distillation during the course of the reaction.

Description

Mo-2359 . LeA 21,086 PROCESS FOR ~E PREPARATIO~ OF
N-~IONO~UBSTITUTE~ O-ALKYLURE~HANES
BACKGROUND OF T~E INVE~ITION
The present invention relates to a process for the preparation of ~ monosubstituted O-alkylurethanes in which primary amines are reacted with N,N'-diarylureas and high boiling monohydric alcohols. The arylamines which split off during this reaction are removed by distillation.
N-monosubstituted O-alkylure-thanes are valuable intermedia~e products and end products which are becom-ing commercially important as plant protective agents and as starting materials in the preparation of iso-cyanates.
N-monosubstituted O-alkylurethanes are conventional-ly prepared by reacting the corresponding isocyanates with alcohols or by reacting corresponding amines with chloroformic acid esters. The isocyanates or chloro-formic acid esters are made using phosgene which re-quires considerable safety measures due ~o i~5 high toxicity.
N-monosubstituted O-alkylurethanes may also be pre-pared by reacting appropriate nitrogen compounds with carbon monoxide in the presence of alcohols. Processes for the preparation of urethanes from nitro compounds by a reaction with carbon monoxide and alcohols have been described in German Offenlegungsschriften

2,603~574 and 29614,101. One disadvantage of this meth-od is that carbon monoxide, which is toxic and combust-~0 ible, must be used under pressure so tha~ elaboratesafety measures are necessary. In addition, such carbonylation reactions require the use of special catalyst systems, which entail considerable costs.

Mo-2359 U~

US Patent 2,806,051 discloses a process Eor the preparation of N-monosubstituted O-alkylurethanes in which primary amines are reacted with urea and alcohols, and the ammonia formed is removed from the reaction mixture. Although the use of urea as startinV
material is theore~ically advantageous, it has been ~ound to be disadvantageous in practice, tparticularly when weakly basic amines or polyfunctional amines are used) because the reaction is accompanied by formation of N-unsubstituted carbamic acid esters as well as cya-nuric acid, polyureids and other irreversible decom-position products of urea as by-products. ~hen N,N'-di-substituted ureas are formed as by-products, they separate as difficultly soluble oligoureas or polyureas if polyfunctional amines are used and may interfere with the production process. The resulting product mixtures may require elaborate and expensive processes for working up, particularly if the reactions have not been complete and the mixtures still contain residual amines. The desired urethane may be obtained in only moderate yields. The difficulties outlined above are particularly pronounced when weakly basic amines or poly~unctional amines are used. These disadvantages are not overcome by the processes described in German Offenlegungsschriften 2,917,493 and 2,917,569, in which di- and/or polyamines are reacted with urea and alcohols.
Similar disadvantages occur in the preparation of N-monosubstituted O-alkylurethanes by the reaction of primary amines ~ith N-unsubstituted carbamic acid esters and optionally urea and optionally alcohols, in which the ammonia formed is removed from the reaction ~o=2359 mixture. This method of preparation has been described, for example, in German Offenlegungsschriften 2,917,490 and 2,917,568 and in European Patent Specifi-cations 0,018,581 and 0,018,583~ These processes ~ive rise to the same irreversible by-products obtained when urea is used as the starting material. Furthermore, N-unsubstituted carbamic acid esters react much more slowly than urea so that the reaction is incomplete, particularly when weakly basic amines or polyfunctional amines are used.
SUMM_ARY OF ~IE INVENTION
It is an object of the present invention to provide a process for the preparation of N-monosubstitu~ed O-al-kylurethanes.
It is also an object of the present invention to pro~ide a process for the preparation of N-mono-substituted O-alkylurethanes in high yield without f~rmation of significant quantities of by-products.
It is another object of the present invention to provide a process for the preparation of M-mono-substituted O-alkylurethanes which is more economical and requires less elaborate safety ~easures than prior axt processes.
These and other oojects which will become apparent to those skilled in the art are accomplished by re-25 acting a primary amine corresponding to a specifiedformula with a urea of a specified formula and a primary or secondary alcohol at a temperature of from 150 to 300C. The amine which forms durlng the re-ac~ion is re~o~ed ~rom the reaction mixture by distil-30 lation on a continuous basis. The reactant alcohol hasa boiling point which is at least 5C higher at atmosph-Mo-2359 ~L~82~

eric pressure than the aromatic amine from ~hich the urea is directed.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a process for the preparation of N-monosubstituted O-alkylurethanes corre-sponding to the general formula Rl (NH CO-OR ) n in which Rl represents an aliphatic hydrocarbon group having a total of 4 to 18 carbon atoms, option-ally containing inert substituents; a cycloali-phatic hydrocarbon group having a total of 6 to 28 carbon atoms, optionally containing inert substituents and/or oxygen, sulfur or alkylene groups as bridge members; an aromatic hydrocarbon group having a total of 6 to 28 carbon atoms~ optionally containing inert sub-s~ituents and/or oxygen, sulfur or alkylene groups as bridge members; or an araliphatic hydrocarbon group having a total of 7 to 28 carbon atoms, optionally containing inert sub-stituents;
R denotes an aliphatic hydrocarbon group having a total of 6 to 18 carbon atoms, optionally containing inert substituents and/or ether groups; a cyc.loaliphatic hydrocarbon group having a total of 6 to 15 carbon atoms, option-ally containing inert substituents; or an aral-iphatic hydrocarbon group having a total of 7 to 18 carbon atoms, optionally containing inert substituents; and n denotes an integer greater`than or e~ual to 1.

Mo 2359 ~%~

These urethanes are made by reacting a primary amine with an N,N'-diarylurea and a primary or secondary alcohol at a temperature o~ from 150 to 300C and con-comitantly removing by distillatlon the aromatic mono-amine R3NH2 which forms. The R3NH? may be re-moved in admixture with the alcohol R -OH.
Primary amines which may be used in the practice of the present invention correspond to the general formula Rl(NH2)n 10 in which Rl and n are as defined above.
Ureas which may be used in the present invention correspond to the general formula R3-NH-CO-N~I-R
in which 15 R3 represen~s an aromatic hydrocarbon group havin~ a total of 6 to 14 carbon atoms, option-ally containing inert substituents, which 'nydrocarbon group is derived from a primary aromatic monoamine (optionally containing inert substituents) having a boiling point at atmospheric pressure at least 1~C below ~he boiling point of the amine Rl (NH2)n.
Primary or secondary alcohols which may be used in the present invention correspond to the general formula in which R is as defined above. The reactant alcohol must have a boiling point at atmospheric pressure which is at least 5C higher than the amine R -N~12.
The primary amines of the above-mentioned general formula used as starting materials are preferably those in which Mo-2359 ~8~

Rl represents a saturated, unsubstituted, ali-phatic hydrocarbon group having 4 to 18 carbon atoms; a saturated cycloaliphatic hydrocarbon group having a total of 6 to 25 carbon a~oms, optionally alkyl substituted and/or carrying methylene bridges, or an aromatic hydrocarbon group having a ~otal of 6 to 25 carbon atoms which is optionally alkyl-substituted and/or halogen substituted and/or carries methylen~
bridges, and lQ n represents 1, 2 or 3, most preferably 1 or 2.
Mixtures of primary amines corresponding to the above-given formula may also be used. These monoamines must have a boiling point at atmospheric pressure which is at least 10C higher, preferably at least 25C
higher than the boiling point of the monoamine from which the reactant disubstituted urea is derived.
Therefore, when the monoamines corresponding to the above-mentioned general formula are alipha~ic or cyclo-aliphatic monoamines without substituents, Rl must have at least 9 carbon atoms. If aromatic monoamines are used, they must be di~ferent from the monoamine from which the reactant urea is derived and must satisfy the difference in boiling points requirement described above.
Examples o suitable primary amines are: decyl-amine, iso-dodecylamine, n-stearylamine, 2~(2-butoxy-ethoxy)-ethylamine, l-butyl-4-methoxy-butylamine , 3-butyl-cyclohexylamine,4-cyc~ohexyl-cyclohexylamine, 4-chloro-aniline3 3,4-dichloroaniline, 3-toluidine, 3-chloro-4-methyl-aniline, 3,5-dimethyl aniline, 4-cyclohexyl-anil-Mo-2359 ~2~

ine, 4-benzyl-aniline, 3-anisidine, 3-amino-benzoic acid nitrile, l-naphthylamine, 2-naphthylamine, 2-phenyl-ethylamine, tetramethylenediamine, hexamethylenediamine, 2 7 2,4-trimethylhexamethylenediamine, isophoronediamine, 1,4-diamino-cyclohexane, 4,4'-diamino-dicyclo-hexylmethane, 2,4-diamino-1-methyl-cyclohexane, 2,6-di-amino-l-methyl-cyclohexane; 4-aminocyclohexyl-4'-amino-phenyl-methane, 6-(2-aminophenyl-mercap~o)-hexylamine, 1,3-diaminobenzene, 2-chloro-1,4-dia~inobenzene, 2,4-di-aminotoluene, 2,6-diaminotoluene, 2,4-diamino-3,5-di-ethyltoluene, 1,5-diaminonaphthalene, 2,7-diamino-naphthalene, 2,2'-diamino-diphenylmethane, 2~4'-diamino-diphenylmethane, 4,4'-diamino-diphenylmethane, 3,3'-di-chloro-4,4'-diamino-diphenylmethane 9 2,2-bis-(4' amino-phenyl)-propane, l,l-bis-(4'-aminophenyl)-cyclohexane, 4,4',4"-tria~ino-triphenylmethane, 4,4'-diamino-diphenylether, 1,3-~ylylenediamine, 1,4-xylylenediamine, 3,4'-diamino-4-methyl-dlphenyl-20 methane, and 4,4'-diamino-diphenyl sulphide.
The diamino-diphenylmethane isomers listed above may also be used as mixtures wi-th higher nuclear homo-logs, i.e. for example in the form of aniline-formal-dehyde condensates known as "polyamine mixtures of the 25 diphenylmethane series"which are obtained in the presence of acid catalysts.
Examples o~ reactant diarylureas which may be used in the present invention are: N,N'-diphenylurea, N,N'-di-(2-tolyl)-urea, N,N'-di-(3~tolyl)-urea, N,N'-di-(4-tolyl)-urea, N,N'-di-(3-e-thylphenyl)-urea, N,N'-di-(4 ethylphenyl)-urea, N,N'-di-(3-methoxyphenyl)-urea, and N,N'-di-(4-methoxyphenyl)-urea. The preferred N,N'-Mo-2359 diphenylurea for the process of the present invention is NrN~-diphenylurea.
The reactant alcohols which may be used in the process of the present invention are primary or secondary, preferably primary D~onohydric alcohols which have a boiling point at atmospheric pressure that is at least 5C, preferably at least 20~C higher than the boiling point of the amine R3-~2 rom which the diarylurea R3-NH-Co-NH-R3 is derived. The alcohols in which R represents a saturated primary aliphatic hydrocarbon group having 6 to 18 carbon atoms ? option-ally contain ether bridges.
Examples o~ suitable alcohols are: straight chained or branched octanol, nonanol, decanol, undecanol, dodec-anol, tetradeeanol, hexadecanol or octadecanol; 2-(2-ethoxy-ethoxy)-ethanol; 2-~2-butoxy-ethoxy)-ethanol;
2-phenylethanol; 2-phenoxyethanol; 2-(2-phenoxy-ethoxy)-ethanol; cyclooctanol, benzyl alcohol; 2,4,5~trimethyl-cyclohexanol; 1,2,3,4-tetrahydro- naphthol-(2); and 20 perhydronaphthol-(2). Mixtures of alcohols R2-OH
may, oE course, also be used.
The diarylureas R3-NH-Co-NH-R3 used in the process of the present invention may be prepared by methods known in the art, for example by the reaction 25 of aromatic amines with carbon dioxide as described in British Patent 622,955. A simple method of preparing diarylureas in high yields, consists of reacting the corresponding arylamines R -NH2 with urea and re-moving the ammonia formed (see also Liebigs Ann. Chem.
30 131, 251 (1864). The diarylurea~ used in the process of the present invention may, however, be prepared by any method.

Mo-2359 The diarylureas R3-NH-Co-NH-R3 used in the process of the present invention need not be hi~hly pure. In particular, admixtures of the corresponding arylamine R3-NH2 in the diarylurea do not inter~ere s wit'n the reaction o~ the present invention because the arylamine R3-NH2 is liberated in the reaction and removed from the reaction mixture by distillation any-way.
In one embodiment o:E the present invention, crude diarylureas R3-NH-Co-NH-R3 obtained by reacting urea with arylamine R -NH2 in a molar ratio o~ from 1:1.8 to 1:10 ~preferably 1:2 to 1:4) at a temperature from 130C to 250C (pre~erably from 150C to 210C) with liberation and removal of ammonia is used as a reactant. Excess arylamine R3-NH2 present in the crude diarylureas may be partially or completely removed (for e~ample by distillation) before the diarylureas are used in the process of the present invention. Alternatively, the crude diarylureas may be used in the present invention without any further treatment.
In the process of the present invention, the re-actants are used in proportions such that the overall molar ratio of amino groups of the amine 25 R (NH2)n to diarylurea R3-NH~Co-NH-R3 is in the range o~ l:l to 1:5, preferably 1:1 to 1:1.5, most preferably 1:1 to 1:1.05. The overall molar ratio of amino groups of the amine Rl (NH2)n to the alcohol R -0~1 should be in the rang~ of 1:1 to 1:20, 30 pre~erably 1:1.5 to 1:1Ø
The reaction of the present inven~ion is carried out at a temperature of from 150C to 300C, preferably 1&0 to 250C.
Mo-2359 ~2~

The pressure used in the process of the present invention should be adjusted so that the arylamine R3-NH2 ~ormed in the reaction and/or already present in the reaction mixture boils (optionally in admlxture with the alcohol R -OH) and can be removed by distillation. The pressure is generally from 0.001 to 1.5 bar, preferably from 0.01 to 1.1 bar.
The reaction of the present invention is generally completed after a reaction time of 1 to 20 hours, pre-ferably 2 to 10 hours, most preferably 3 to 6 hours.The reaction may be accelerated by the addition of a catalyst to the reaction mixture. Suitable catalysts include Lewis acids such as BF3, BC13, B(OC2H5~3~ B(OC4Hg)3, AlC13, AlBr3, SnC14, dibutyl tin oxide, SbC15, TiC14, TiBr4 FeC13, cobalt octoate, ZnC12, zinc octoate, CuCl, and/or salts and comple~ compounds of transition metals other than those belonging to the group of Lewis acids, such as iron carbonyls, acetylacetonates of iron3 20 nickel, cobalt, zinc, manganese, molybdenum, ~itanium, thorium, vanadium or zirconium, and bls-(dibenzoyl-methane)-copper. Mixtures of such compounds may, of course, also be used as the catalyst.
Particularly suitable catalysts-are zinc chloride, 25 zinc acetate, zinc octoate, zinc oxide, tin dichloride, tin tetrachloride, dibutyl tin oxide 9 dibutyl tin di-e~hylate, dimethyl tin dichloride, dibutyl tin di-laurate, cobalt trichloride, cobalt triacetate, copper chloride and copper acetate.
The catalyst, if used at all, is generally added to the reaction mixture in a quantity of 0.001 to 5 wt. %, preferably 0.01 to 2 wt. % (based on the total weight Mo 2359 of the starting materials). One would, of course, aim to keep tlle concentration of catalyst as low as possible. The optimum catalyst concentra~ion depends on the nature of the starting materials and the activity of the particul2r catalyst, and may be determined by a simple preliminary test.
In the process of the present in~ention, the reaction may be carried out by mixing the amine Rl(NH2)n, diarylurea R3~NH-Co-NH-R3 and alcohol R2-OH and heating -the mixture in a distillation apparatus at the required pressure. The arylamine R3-NH2 formed in the course of the reaction or possibly already present in the reaction mixture is removed by distillation.
~hen carrying out the reaction of the present inven-tion, it may be advantageous to first heat the diar~l-urea R3-NH-Co-NH R3 and the alcohol R2 OH to the required temperature at the necessary pressure in a distillation apparatus in the absence of the amine 20 Rl (NH2)n or with only a proportion of the amine R (~H2)n and then add the amine R 'NH2)n or the remainder of ~he amine R (NH2)n into the reaction mixture (op~ionally together wi~h the alcohol R -0~) at a suitable rate. This method makes it 25 possible to avoid the presence of undeslrably high con-centrations of the amine Rl(NH2~n in the reaction mixture. This may be par~icularly important when using polyfunctional amines Rl(NH2)n which form in-soluble or difficultly soluble polyureas in the re-30 action mixture.
Removal of the arylamine R3-~2 from the re-action mixture by distillation as it is formed shifts Mo-2359 the reaction equilibrium in the direction of the de-sired end product, thereby ensu-ring quantitative conver-sion of the amine Rl(N~2)n. Removal of the aryl-amine R3-NH2 from the reaction ~mixture may be carried out by any known distillation method. One such method is a stripping distillation in which a condenser is attached to the reac~ion vessel. It is generally advisable, however, to fractionate the vapors escaping from the reaction vessel by using a frac-tionating column or a separating column. Fractionation techni-ques make it possible to prevent removal of portions of the amine Rl(~H2)n or of undesirable large quanti~
ties of alcohol R -OH from the reaction mixture along with the arylamine R3-NH2.
It is not essential to the process of the present invention that the arylamine R3-NH2 distilled from the reaction mixture be free from alcohol R -OH. It may even be an advantage, particularly towards the end of the reaction to remove portions of alcohol R2-OH
from the reaction mixture together with the arylamine R3-NH2 provided that sufficient quantities of alcohol R2-o~ are le~t be'nind for the reaction.
The process of the present invention may be carried out continuously or batchwise. For a continuous pro-cess, it is advantageous to provide a series of re-action vessels arranged in a cascade. It may then be advantageous to use di~ferent reaction temperatures, reaction prassures and/or average dwell times in the various reaction vessels. Fractionation of the vapors containing the arylamine ~3-~H2 released from the reaction vessels may be carried out separately in each reaction vessel (or example by attaching fractionating Mo-2359 columns ~o the various vessels) or after mixing the vapors from the various columns.
Any known apparatus may be used to carry out the process of the present invention continuously.
~hen the reaction has been completed, any excess alcohol R2-OH left in the reaction mixture may be separa~ed ~rom the end product ~y distillation, prefer-ably at reduced pressure.
The products obtained in the process of the present invention are N-monosubstituted O-alkylurethanes corres-ponding to the formula Rl(NH-CO-OR )n in which R , R and n are as defined above. The process of the present invention proceeds according to the ~ollowing equation:
Rl(NX2)n + n R3-NH-Co-NH R3 + n R2-OH
~ R (NH-CO-OR )n + 2n R -NH2 It was completely unexpected that the ormation of substituted ureas derived from the amine Rl(NH2)n is virtually eliminated in the process of the present invention. The absence of polyurea formation when poly-functional amines are used is particularly surprising.
Since the reaction is carried out at temperatures at which O alkyl-urethanes normally decompose into iso-cyanates and alcohols, one would have expected the for-mation of isocyanates corresponding to the formula Rl(NH~CO-OR2)n m(NCO)m 1 2 in the reaction mixture (~ith R , R and n being as de~ined above) with n - m denoting a positive integer.
One would have expected these isocyanates to combine with the amine component Rl (NH2)n to form un-wanted ureas, however, this side reac~ion does not occur to any significant extent.
Mo-2359 :' The products obtained by the process of the present invention are carbamic acid esters based on relatively high boiling alcohols If however, it is desired to obtain carbamic acid esters based on lower boiling alcohols ~as may be the case when preparing isocyanates by thermal splitting of O-alkylurethanes), the products of the process may be transurethanized to the desired products by an exchange reaction with the corresponding lower boiling alcohol. This method has been descxibed, for example, in &erman O-ffenlegungsschrirt 29 43 549.
Having thus described our invention, the following Examples are given by way o illustration. The per centages given in these E~amples are percents by weight, unless otherwise indicated.
EXAMPLES
15 Example 1 236 g of n-decylamine, 320 g of N,N'-diphenylurea and 900 g of 2-phenyl-ethanol were introduced into a 2 liter round bottomed flask with a packed column at-tached. The mixture was heated to 210C with vigorous 20 stirring. Stirring was continued at 210C at atmo-spheric pressure for 4 hours, during which time aniline was distilled over -the column. The reaction tempe-rature was then raised to 230C and phenyl ethanol was distilled off for 15 minutes. The crude mixture was 25 then Ereed from mos-t of the phenyl ethanol excess present by ~he vacuum distillation (ini-tially at 20 mbar, finally a 1 mbar). The 472 g of crude product left behind was analyzed by liquid chromatography ~HPLC). 96.l wt. % of the crude product consisted of 30 N-decyl-0-(2--phenyl-ethyl)-urethane. ~Yield: 99~ of the theoretical yield) A to~al of 279 g of aniline was detected in the distillate.
Mo-2359 ,4~

Example 2 420 g of aniline and 92 g of urea were introduced into a 2 liter round bottomed flask wit'n reflux con-denser attached. The mixture was heat~d to 190C with-in 30 minutes with stirring. Am~onia gas was released,removed by way of the reflux condenser and absorbed in water in a scrubber. After an additional 1.5 hours, during which the reaction temperature was raised to 200C, liberation of ammonia was completed. The appa-10 ratus was briefly flushed with nitrogen to remove resi-dues of ammonia gas. The reflux condenser was then replaced by a distillation bridge. A solution of 404 g of n-stearylamine in ~00 g of n-dodecanol heated to a temperature of 190C was then introduced into the re-15 action mixture with vigorous stirring. The mixture washeated to 230C and stirred for 5 hours a-t this temper-ature and at atmospheric pressure, during which ~ime a mixture of 417 g of aniline and 77 g of dodecanol dis-tilled over. Most of the excess dodecyl alcohol was 20 then distilled of under vacuum and 774 g o crude product remained behind. 5~18 g of the crude product were separated by column chromatography against silica gel. 4.73 g of N-octadecyl-O-dodecyl-urethane were isolated. This corresponds to a yield of 98% of the theoretical yield.
Exam~le 3 163 g of 2-12-(2 methoxy-ethoxy)-ethoxy~
-ethylamine, 213 g of ~,N'-diphenylurea and 700 g of 2 phenoxy-ethanol were introduced into a 2 liter round bottomed flask with a packed column a~tached. The mixture was h~ated to 220C at atmospheric pressure with vigorous stirring. Aniline was liberated and Mo-2359 distilled over the column. The reaction temperature was raised to 233C in the course of 4 hours, during which aniline continued to be released and distilled off. The major part of the excess alcohol was then removed from the reac~ion mixture by vacuum distillation (first at 20 mbar, then at 1 mbar) and 333 g of liquid crude product were left behind. According to liquid chromatographic analysis (HPLC), the crude product contained 96.6 wt % of N-2-~2-(2-methoxy-ethoxy)-ethoxy~-ethyl-O-(2 phenoxy -ethyl)-urethane (yield: 98% of theoretical yield). A
total of 186 g of aniline was detected in the distlllate.
Exam~le 4 320 g of aniline and 73 g of urea were introduced into a 2 liter round bottomed flask with a packed column attached. The mixture was heated to 190C for 30 minutes with stirring. During this time, ammonia gas was released, conducted away through the column and absorbed in water. After an additional 1.5 hours, during which the reaction temperature was raised ~o 200C, the release of ammonia was completed. The appa-ratus was briefly -flushed with nitrogen, A solution of 170 g of 3-chloro-4-methyl-aniline in 900 g of n-decanol heated to 190C was added to the reaction mixture with stirring. The mixture was then stirred for 5 hours at 225C and atmospheric pressure and aniline was concomitantly distilled over the column.
The pressure was then 510wly reduced to 500 mbar until pure decyl alcohol distilled over. Most of the decanol excess was then distilled from the reactlon mixture, first at 20 mbar, then at 1 mbar, and 370 g of crude Mo-2359 product remained behind. According to liquid chroma-tographic analysis (HPLC), the crude pro~uct contained 95.7 wt. % of N-(3-chloro-4-methyl-phenyl~-0-decyl-urethane (yield: 98% of t'neoretical yield). A
total of 318 g of aniline was detected in the distillate.
Exam~le 5 A mixture of 195 g of 3,4-dichloroaniline, 257 g of N,N'-diphenylurea and 1000 g of 2-phenoxy-ethanol was lO heated to 230C with vigorous stirring in a 2 liter round bottomed flask with a packed column a~tached.
Aniline was distilled of over a period of 6 hours at 230C and atmospheric pressure. The pressure was then lowered to 500 mbar and distillation was continued 15 until pure phenoxy-ethanol distilled over. Most of the phenoxy-ethanol excess was then separated by vacuum distillation. 407 g of crude product remained behind.
According to liquid chromatographic analysis (HPLC), this crude product contained 93.8 wt. % of 20 N-(3~4-dichlorophenyl)-o-(2-phenoxy-ethyl)-urethane (yield: 97% of theoretical yield~. The crude product was recrystallized from ligroin and yielded colorless crystals melting at 79 to 81C. A total of 222 g of aniline was detected in the distillate.
25 Example 6 470 g of aniline and 122 g of urea were heated to 190C with vigorous s~irring within 30 minutes in a 2 liter round bottomed flask equipped with a packed column and a dropping funnel adapted to be heated.
30 Ammonia gas was released, escaped through the column and was absorbed in water. Liberation of ammonia was completed after an additional 1.5 hnours during which - ~o-2359 .
. .

4~i~

the temperature was raised to 204C. The apparatus was briefly flushed wlth nitrogen. 800 g of decanol at 200C and 1 g of dibutyl tin oxide were then added to the reaction mixture and the mlxture was heated to 220C. A solution of 116 g of hexamethylene diamine in 400 g of n-decanol at 50C was introduced dropwise within 4 hours with stirring at: atmospheric pressure into the mixture which mixture was at a temperature of 220C. At the same time, aniline was distilled off over the colu~l. After addition of the solution of hexamethylene diamine had been comple~ed, the reaction mixture was stirred for an addtional hour at 220C and atmospheric pressure while aniline distilled over. The pressure was then lowered to 500 mbar until pure decanol distilled over. Lastly, most of th~ decanol excess was separated by vacuum distillatlon and 502 g of crude product remained behind. 4.93 g of the crude product were separated by column chromatography against silica gel. 4.69 g of hexamethylene-bis-caxbamic acid-bis- decyl ester were obtained in the form of crystals with a melting point of 113C (yield: 99% of theoretical yield). A total of 467 g of aniline was detected in the distillate.
Example 7 A mix~ure of 427 g of N,N'-diphenylurea9 1000 g of 2-phenoxy-ethanol and 1.5 g of dibutyl tin oxide was heated to 215C with s~lrring in a 2 liter round bot-tomed flask equipped with dropping funnel and a packed column. After the pressure had been adjusted to 600 mbar, a solution of 116 g of hexamethylenediamine in 400 g of 2-phenoxy-ethanol was introduced dropwise in the course of 4 hours into the homogeneous liquid re-Mo-2359 _ 19-action mixture which was at a temperature of 215C
while aniline was distilled over the column. After addition of the solution of hexamethylenedîamine had been completed, aniline continued to be distilled off for an additional hour at 215C and 600 l~bar. The pressure was then slowly reduced until pure phenoxy ethanol distilled over. Lastly, most of the phenoxy ethanol excess was removed by vacuum distillation and 465 g of crude product remained behind According to liquid chromatograp'nic analysis (HPLC), 93.6 wt. % of the crude product consisted of hexamethylene-bis-carbamic acid-bis-(2-phenoxy-ethyl)-ester (yield: 98%
of theoxetical yield). Recrystalliza-tion of the crude product from 1,2-dichloroethane yielded colorless crystals with a melting point of 152C. A total of 370 g of aniline was detected in the dis~illate.

A mixture of 426 g of N,N'-diphenylurea and 1000 g of 2-phenoxy-ethanol was heated to 230C with vigorous stirring in a 2 liter round bottomed flask equipped with dropping funnel and a packed column. A solution of 210 g OL trans, trans-4,4'-diamino-dicyclo-hexylmethane in 400 g of 2-phenoxy ethanol was intro-duced dropwise in the course of 4 hours at atmospheric pressure into the mixture which was at a temperature of 230C, and aniline was at the sa~e time distilled over the column. After all the solution of dicyclohexyl-methane had been added, stirring of the mixture was continued -Eor an additional 1.5 hours at 230C while ~ aniline disti~led over. The pressure was then reduced until pure phenoxy-ethanol distilled over. Lastly, mos~ of the phenoxy-ethanol excess was removed from the Mo-2359 reaction mix~ure by vacuum distillation and 566 g of cr-ude product remained behind. According to liquid chromatographic analysis (HPLC), the crude product contained 94.2 wt. % of dicyclohexylmethane-4,4'-bis-carbamic acid-bis-(2-phenoxy-ethyl)-ester (yield: 99% of theoretical yield). A total of 373 g of aniline was detected in the distillate.
Example 9 A mixture of 426 g of N,N'-diphenylurea, 122 g of 2,4-diaminotoluene, 1300 g of 2-phenoxy-ethanol and 2 g of dibutyl tin dilaurate was heated to 230C with vig-orous stirring in a 2 liter round bottomed flask with a packed column attached. The reaction mixture was stir-red at 230C and atmospheric pressure for 6 hours while aniline was distilled over the column. The pressure was then lowered over 30 minutes until pure phenoxy ethanol distilled over. Most of the phenoxy ethanol excess was finally removed from the reaction mixture by vacuum distillation. 455 g OL crude product remained behind. According to liquid chromatographic analysis (HPLC), the crude product contained 94.7 wt. % of toluene-2,4-bis-carbamic acid-bis (2-phenoxy-ethyl)-ester (yield: 96% of theoretical yield).
Recrystallization of the crude product from ethanol yielded almost colorless crys~als with a mel~ing point of 137C. A total of 364 g o aniline was detected in tne distillate.
Example 10 A mixture of 430 g of 3-toluidine and 97 g of urea was heated to 210C for 30 minutes with vigorous stir-ring in a 2 liter round bottomed flask with dropping funnel and a packed column. Ammonia gas was released, Mo-2359 8 ~

conducted away through the column and absorbed in water. After the reaction had been continued for an additional 1.5 hours at 210C, the liberation of ammonia was completed. The apparatus was briefly flushed with nitrogen. 1000 g of n-dodecanol heated to ~00C and 2 g of dimethyl tin dichloride were then added to the reaction mixture and heated to 230C.
After the pressure had been adjusted to 500 mbar, a solution of 98 g of 2,4-diaminotoluene in 350 g of do-decanol was introduced dropwise in the course o~ 4hours into the reaction mixture which was at a temper-ature o 230C, and 3 toluidine was distilled over the column at the same time. ~hen all the solution of 2,4-diaminotoluene had been added, the mixture contin-ued to be heated to 230C for an additional 2 hours at500 mbar while toluidine continued to distill over.
The pressure was then slowly lowered until pure do-decanol distilled over. Finally, most of the dodecanol excess was removed from the reaction mixture by vacuum distillation. 475 g of crude product remained behind.
According to liquid chromatographic analysis (HPLC), ~he crude product contained 90.6 wt. % of toluene-2,4-bis-carbamic acid -bis-dodecylester ~yield:
98~ of theoretical yield). The crude product was 25 recrystallized from ligroin and yielded almos~
colorless crys~als with a melting point of 82C. A
total of 425 g of 3-toluidine was detected in the distillate.
Example 11 A mixture of 330 g of aniline and 86 g of urea was heated to 190C over a period of 30 minutes with stir-ring in a 2 llter round bottomed flask eq~ipped with Mo-2359 ~182~

dropping funnel and a packed column. The ammonia gas released during this time was removed through the column and absorbed in water. After an additional l.5 hours during which the temperat:ure was raised to 205C, liberation of ammonia was comp].eted. The apparatus was briefly flushed with nitrogen. 800 g of decanol heated to 200C were then added to the reaction mixture and the mixture was heated to 220C:. A solution of 140 g of 4,4'-diamino-diphenylmethane in 300 g of n-decanol 10 was then introduced dropwise into the reaction mixture which was at 220C, in the course of 4 hours with stir-ring at atmospheric pressure while aniline distilled over the column. When all of the solution of diamino diphenylmethane had been added~ stirring was continued 15 for an additional hour at 220C and atmospheric pressure while aniline distilled over. The pressure was then slowly reduced until pure decanol distilled over. Finally, st of the decanol excess was removed from the reaction mix~ure by vacuum distillation and 20 407 g of crude product remained behind. According to liquid chromatographic analysis (HPLC), the crude product contained 96.2 wt. % of diphenyl-methane-4?4'-bis-carbamic acid-bis-decyl ester (yield:
98% of theoretical yield). Recrystallization of the 25 crude product from ethanol yielded colorless crystals melting at 116C. A total of 327 g of aniline was de-tected in the distillate.
Example 12 A mixture of 323 g of N,N'-dipheny~urea, 150 g of 30 4,4' diamino-dip~enylmethane, 1200 g of 2.-(2-butoxy~ethoxy)-ethanol and 1 g of dibutyl tin oxide was heated to 210-212C with vigorous stirring in Mo-2359 a 2 liter round bottomed flask with a packed column attached. Heating was continued at 212C and atmos-pheric pressure for 6.5 hours while aniline was dis~illed over the column. The temperature was then rai~ed to 230C and distillation was continued for 30 minutes. Finally, most o~ the butoxy-ethoxy-ethanol excess was removed from the reaction mixture by vacuum distillation. 432 g of crude product remained behind.
According to liquid chromatographic analysis (HPLC), the crude product contained 95.9 wt. % of diphenyl-methane-4,4'-bis-carbamic acid-bis-[(2-butoxy-ethoxy) -ethyl]-ester (yield: 95% of theoretical yield). A
to~al of 275 g of aniline was detected in the distillate.
Example 13 A mixture of 350 g of aniline and 85 g of urea was heated to 190C for 30 minutes with stirring in a 2 liter round bo~tomed flask equipped with dropping funnel and a packed column. Ammonia gas was released and conducted away over the column and absorbed in water. After an additional 1.5 hours, during which the temperature was raised to 205C, the release of ammonia was completed. The apparatus was briefly flushed with nitrogen. 1000 g of 2-phenoxy-ethanol heated to 200C
were then added to the reaction mixture and the mixture was heated to 230C. 140 g of a commercial mixture of 4,4'-, 2,4'- and 2,2'-diamino-diphenylmethane and poly-phenyl-polymethylene-polyamine having an analyzed equiv-alent weight of 99.9 ~based on the amino group) were then introduced dropwise with vigorous stirring over a period of ~ hours at atmospheric pressure into the reaction mixture which was at a temperature of 230C, Mo-2359 while aniline was distilled over the column. After addition of the amines had been completed, the mixture continued to be stirred for an additional 2 hours at 230-235C and atmospheric pressure while aniline was distilled over. The pressure was then reduced until pure phenoxy-ethanol distilled over. Lastly, most of ~he phenoxy-ethanol excess was removed from the reaction mixture by vacuum distillation and 387 g of crude product remained behind. According to analysis by tltration (HClO~ in glacial acetic acid), this crude product contained a total of 0.015 mol of amino groups, which corresponded to 99% conversion of the amino groups. The residual amount of 2-phenoxy-ethanol in the crude produc~ was found to be 3.7 wt. % accord-ing to separation by column chromatography using silicagel. The crude product consisted substantially of a mixture of the carbamic acid(2 phenoxy-ethyl)-ester corresponding to the amine put into the process, as demonstrated by an infra-red spectroscopic 20 comparison with an authentic substance prepared from the same amine by a different method. A total of 348 g of aniline was detected in the distillate.

~o-2359

Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the preparation of N-mono-substituted O-alkylurethanes corresponding to the general formula R1(NH-CO-OR2)n wherein R1 represents an aliphatic hydrocarbon group having a total of 4 to 18 carbon atoms, optio-nally containing inert substituents; a cyclo-aliphatic hydrocarbon group having a total of 6 to 28 carbon atoms, optionally containing inert substituents and/or optionally containing oxygen, sulfur or alkylene groups as bridge members; an aromatic hydrocarbon group having a total of 6 to 28 carbon atoms, optionally containing inert substituents and/or optionally containing oxygen, sulfur or alkylene groups as bridge members; or an araliphatic group having a total of 7 to 28 carbon atoms optionally containing inert substituents, R2 represents an aliphatic hydrocarbon group having a total of 6 to 18 carbon atoms, optionally containing inert substituents and/or ether groups; a cycloaliphatic hydrocarbon group with a total of 6 to 15 carbon atoms, optionally containing inert substituents; or an araliphatic group having a total of 7 to 18 carbon atoms, optionally containing inert substituents; and n represents an integer greater than or equal to 1, comprising reacting (a) a primary amine corresponding to the general formula R1(NH2)n in which R1 and n are as defined above, with (b) a urea corresponding to the general formula in which R3 represents an aromatic hydrocarbon group having a total of 6 to 14 carbon atoms optionally containing inert substituents which hydrocarbon group constitutes the basis of a primary aromatic monoamine optionally containing inert substituents, which monoamine has a boiling point at atmospheric pressure which is at least 10°C below the boiling point of the amine R1(NH2)n, and (c) a primary or secondary alcohol corresponding to the general formula in which R2 is as defined above which alcohol has a boiling point at atmospheric pressure that is at least 5°C higher than that of the amine R3-NH2, said reaction being carried out at a temperature from 150 to 300°C, with the amine R3-NH2 formed being removed from the reaction mixture by distillation during the reaction.

2. The process of Claim 1, wherein the urea starting material (b) is a crude diarylurea prepared by reacting urea with arylamines R3-NH2 in a molar ratio in the range of 1:1.8 to 1:10 at temperatures from 130°C to 250°C with liberation and removal of ammonia.

3. The process of Claim 1 or 2, in which the urea used is N,N'-diphenylurea.

4. The process of Claim 1 in which the amine R3-NH2 formed during the reaction is removed from the reaction mixture as a mixture with alcohol R2-OH.