US2313636A - Fractionation of free fatty acids - Google Patents

Description

Patented Mar-9,1943

UNITED STATES PATENT OFFICE Stephen E. Free wauwatosa, Wia, assignor man, to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania No Drawing.

Original application January 17,

. 1939, Serial No. 251,340. Divided and this ap- Dlioation May 13, 1940, Serial No. 335,001

4 claims. (01. 260-419) Thetpresent invention relates to the treatment of fat and oils, of the glyceride type, and it has particular relation to the treatment of glyceride One object of the invention is to separate an,

oil of the glyceride type into various fractions each or most of which will have greater value than the original oil when the fraction is suitably selected for use in paints, synthetic resins, food products, plastics, soaps, etc.

For example, the invention provides a simple and convenient method of separating oils comprising mixtures of glycerides of fatty acids of different degree or types of unsaturation into fractions certain of which contain a higher ratio of the more unsaturated or more actively unsaturated components than the original mixture.

A second object of the invention is to provide a method of extracting such glyceride oils as linseed, soy-bean, cottonseed, fish oil, train oil and similar oils from pulps or meals containing them, while leaving most of the phosphatides in a readily removable form in the meal.

A third object of the invention involves the provision of a, simple and convenient method of separating mixtures of saturated and unsaturated free fatty acids into fractions, one of which is relatively more saturated than the other. These and other objects will be apparent from consideration of the following specification and the appended claims.

Oils of the glyceride type such as are employed in the preparation of foods, soaps, or as filmforming ingredients in many paints, varnishes and enamels are found in certain plants or in the eral or type structure of these glycerides may be represented by the formula:

H-C-O R1 The principal difl'erence between these glycerides, aside from variations in the number of ester groups, consists in variations in the length of the carbon chains, and in the number and arrangement of the double bonds in the alkyl groups or residues. For example, palmitic acid of the formula I( :)uC or: contains 16 carbon atoms while stearic acid contains 18 carbon atoms. The formula of stearic acid is QHKCHQMC on Both are free of double bonds and are non-drying, Oleic acid of the probable formula.

CH3 (CH2) 7CH2CH(CH2) 1COOH has 18 carbon atoms and contains a singl double bond, but its glyceride is non-drying. Linoleic acid which also contains 18 carbon atoms has two non-conjugate double bonds and these bonds by reason of their number are of such activity that the glycerides posssess drying properties.

The folllowing constitutes the formulaof this acid:

.HHHHHHTIHHHH HO- J;-

i I, ttt i 1.

c cid (9,12,15-octadecatrienoic acid)- differs only 1 having an additional double bond:

HHHH HHHHHHH H H o Ht-t-tkdtatttait- -tli-cfim l I I l I I I H H H 11 H n l817l6l5l413121ll09 876.543 Elaeostearic acid and licanic acid, glycerides of which occur in tung oil and oiticica oil respectively contain double bonds in conjugat relationship in which they are extremely active, and their glycerides dry faster than any of the forearr- Linoleni I going.

Elaeostearic acid (9,11,13 octodecatrienoic acid) is of the formula:

These glyceride oils are customarily extracted from the seed meals or other material containing them by application of high pressure, or by extraction with a suitable organic solvent, such as hexane. Both ofthese methods are objectionable for numerous reasons. For example, in case pressing is resorted to, the removal of oilis incomplete and in event the percentage of oilin 2 I the meal or pulp is initially low, the unextracted oil may-constitute a very large percentage of the total. Extraction by means of organic solvents, such as hexane involves a very high' explosion hazard, and violent explosions often resulting in 'loss of life-are not uncommon in plants emp1oy-.

ing such process. Both processes are objectional because of non-selectivity. For example, in either the pressing operation or the solvent extraction with a hydrocarbon solvent 0.5 .t 1.% phosphatides, 1 or 2% free fattty acids are obtained in the extracted ofls. Non-drying constituents such as realtively highly saturated glycerides are also removed in the oil; At the same time cernishes and lacquers. They are also useful as modifiers in resins. The saturated glycerides and the hydrogenated or unhydrogenated glycerides of a low degree of saturation are useful in foods and the like. The free acids of all types are useful in the preparation or resins, plastics and soaps and other important applications. The phosphatides are of value in foods, pharmaceutical preparations and as emulsifying agents, etc.

It islthe object of refining processes for such oils to remove atleast a part of certain of the constituents which for specific purposes are objectionable. For the paint and varnish industries it is particularly desirable to remove those portions which cause o-called break or sludge formation upon heating, and to remove excess free fatty acids, color and non-drying portions. The conventional method of refining these oils involves the application either of strong sulphuric acid 'which chars and ,coag'ulates the by-product portions, or treatment with sodium hydroxide. Both of these methods are drastic in their action upon the oil destroying some portions entirely, thus producing a by-product which has little or no value. In addition to causing destruction or degraduation of the by-products, such treatment also tends to decompose a part of the drying, or

film-forming glycerides. The methods are tedious and require considerable equipment and much space for storage purposes. Furthermore, the reagents employed in the process are not recoverable and along with the by-products which are obtained in a degraded form constitute a considerable source of loss.

The present invention involves as one feature the discovery that certain types of non-reactive organic polar solvents notably those which, at low temperatures, are not completely miscible with glyceride oils, may by proper control of temperature be employed preferentially to dissolve unsaturated or more actively unsaturated components oi glyceride oils either from simple or crude mixtures of the glycerides, or from materials such as seed meals or pulps containing the glycerides. Accordingly, by treating the oils, or

- materials, such as seed meals or pulps contain-' ing the oils, with'one or more of the selective solvents at a temperature sufliciently low to obviate complete solution of the oil and at a temperature high enough for the solvent to be liquid, it becomes possible to separate the mixture into two liquid components, one comprising the solvent saturated wtih a fraction rich in unsaturates, the second consisting of glycerides which are relatively poor in unsaturates.

These liquids contain activating groups, which usually are polar and which may be selected from a relatively large class among which may be enumerated the following:

Secondary or tertiary carbon atoms in a hydrocarbon nucleus and the positions of the various groups in the molecule exert a substantial influence upon the characteristics of treating liquid.

The capacity of these groups to activate the molecules of which they are constituents is variable. In general, there must be at least one activating or polarizing group for every four carbon atoms and in many cases the ratio of the groups must be substantially increased.

The permissible number of carbon atoms in the molecule of the solvent for each activating group Ntr l PO o In most cases the applicability of a particular solvent for the fractionation of glyceride oils can be determined from the above table in which the permissible carbon atoms for each of the morecommon of the polar or activating groups are listed. In order to determine if a particular solvent is applicable, the number of permissible carbon atoms for all of the activating groups are added together. If the sum is equal to or greater than the number of carbon atoms actualLv present in the nucleus of the solvent molecule,

- the latter can usually be employed selectively to dissolve unsaturated glycerides from more saturated glycerides.' The operation of the rule is illustrated by furfural The latter contains two double bond (C=C) groups, one oxy linkage corresponds to the number of carbon atoms in the furfural nucleus.

and an aldehyde In the case of groups having but low activating power, e. g.

I O-, etc., it is usually necessary that an additional and more active group be included in the molecule. However, the groups of low activating power then increase the selective action of the molecule for unsaturates. This is also true with the halogens, such as chlorine and bromine.

It will be apparent that most of the solvents, if sufliciently heated, will become miscible with all components of the oil. According y. the tempera: ture must be sumciently low and ratio of the solvent must be maintained in a region where solution is incomplete. Usually, the lower the temperature of treatment (within reasonable limits) the more selective will be the solvent and the higher will be the proportion of the unsaturates in the fraction dissolved. However, the proportion of the glycerides recovered in the dissolved fraction is also decreased. Therefore, in commercial operations it is preferred to compromise between extreme selectivity and high yields, and to employ the solvent at such temperature and in such proportion that two fractions separate but that a reasonable yield is obtained in the dissolved fraction.

In the practice of the invention, it is preferred to treat the oils containing saturated and unsaturated glycerides at the temperature and in a ratio at which separation into fractions occurs. The treatment of oil or meal may be by batch, or multistage, or counter-current or concurrent flow, or by combination of these methods.

In the application of the process to meals or pulp in order to remove the oil therefrom, the material to be treated containing an oil, e. g. soybean oil, or linseed oil, or marine oil, or the like may be treated at a temperature suflicient to dissolve all or a substantial proportion of the oil therein. The liquids are separated from the-solids and the temperature is adjusted to obtain separation into two liquid phases, one of which is rich in relatively saturated glycerides and contains a small amount of solvent and the second consists of solvent in which is dissolved a fraction rich in unsaturates. The ratio of solvent to 011 must not be too low because an undue proportion of it will be dissolved in the more saturated fraction and there will not then be suflicient amount satisfactorily to dissolve and separate the more unsaturated fraction. Conversely, if too. much solvent is employed an excessive amount of saturates will be taken into solution and fractionation cannot be accomplished. Probably in most instances the solvent should be within a range of two to twelve parts by volume of solvent to one part of oil. In batch extractions, a ratio of about four parts of solvent to one part of oil has been found to be a good average. Mechanical separation of the two fractions by settling and decanta tion, or by centrifugation may be easily affected. The solvent can be recovered by steam distillation or by crystallization or by the addition of a nonsolvent for the oil such as water, in order to cause an alteration of the characteristics of the solvent, etc.

A series of tests was conducted upon soy-bean oil having an iodine number of 136, the solvents were employed inthe ratio of four parts to one part of oil. In the event liquid separation did not occur at room temperature the mixtures were chilled. The chilling was continued until separation of two liquid fractions occurred, or if no separation took place, to a temperature of -20 C. The solvents tested are listed in the following table. In the event that solidification of one or more components of the mixture occurred before liquid separation took place the mixture was recorded as miscible. The third column in which the number of carbon atoms in the molecule is listed in the column and the maximum number of carbon atoms theoretically permissible as calculated by assignment of numbers from table A to the activating groups are included in the last column.

Those solvents capable of separating the oil into two fractions are designated as I. Those which do not so separate are designated as M.

TABLE B Carbon atoma o b il it t fluted Solvent C as maxior abov In the mum molecule permissible for immiscibility Hydroxyl:

Methyl alcohol I l 3 Ethyl alcohol I 2 3 n-Propyl alcohol.. I 3 3 iso-Propyl alcohoL I 3 3 n-Butyl alcohol M 4 3 iso-Butyl alcohol M 4 3 'Iertiary-butyl alcohol M 4 3 n-Am alcohol M 5 3 isoAmyl alcohol. M 5 3 sec.-Amyl alcohol M 5 3 Capryl alcohoL M 8 3 Cyclohexyl alcohol. M 6 3 Ethylene glycol I 2 6 Propylene glycol. I 3 6 Glycerine I 3 9 Hydroxyl, Ester.

Methyl glycolate I 3 6 Ethyl glyoolate I 4 6 Beta-hydroxy ethyl acetate. I 4 6 Methyl lactate I 4 6 I 5 6 M 7 6 I 5 9 I 7 9 4- a,a1a,eae-

TAIL! B-Contlnued C r m'- Carbon mmc 1- Mleclculated culatcd Solvent E u maxl- Solvent u marla sa In the mum In the mum molecule 9' molecule permlellble for alhle for 1m lmmlaclblllty billty Hydroxyl, carbonyl: Aldehyde. ct hen-Continued Methyl butanolone Clnnammdehyde Acetyl methyl carblnol. Crotonalxieh do... Diacetone alcohol Benzalde-Jy e Hydroxyl, ether: m-Nltro nzaldehyde h-Methoxy ethanol cubonyk b-Ethoxy ethanol Acetone h-Butoxy ethanol. Methyl ethyl ketone- Dlethylene 5] col... Bu ne 'lrlethylene 3 col 0 Met yl aobutyl ketone- Monoethyl et at of dlethylene Dflsoblr'yl ketone glycol Dlacetyl Mono-butyl ether of dlethylene Acetonyl acetone glycol Carbonyl, ether, double bonds: Z-hydroxy methyl 1,3-d1oxolane. to

Hydroxyl, double bonds- Allyl alcohol Geranlol: Hydroxyl, triple bond:

Dlmethyl ethynyl carblnol Hydroxyl, halogen:

Ethylene chlorohydrln Propylene ohlorohydrln Glycerol monochlorohydrln.-.. Hydroxyl, other:

Beta-hydroxy propionltrlle 2,4'dlchlorophenol 2- bromo 4-tertiary-bn lphenol. Diethyl amino ethane Sallcylaldehyde Cal-boxy]:

Proplonlc acld Ieobutyrlc acid.

Acid Anhydride Ace Ester Methyl acetoacetate Ethyl aoetoacetate Ester ether:

ethyl oellosolve acetate Cellosolve acetate Ester, lmldo:

Ethyl N-meth l carbamate Ester, double bon Ethyl maleate.. e. Ester-Double bond-Ether:

Methyl turoaten Furtury Ester, trlple bond:

, Dlmethyl ethynyl carhinol acetate Eater, halogen Methy chloroacetate Ethyl dlchloro acetate Ester, cyanide:

Methyl cyano acetate Aldehyde:

Octylaldehyde Aldehyde, other:

Methoxy acetaldehyde Furlural o-u-q H g gal-t Hgg H 2H HHHH Hr-u-n-n-lggmgm an ggr-u-u gHggHHzHHb-Hq HHH a 0-1 HHzHH t-lI-u-q a-A I H u e-u- Q 53MB O b20868 lb 000 lib Q bib GQQO OOGGONNQWH #0! NM Q'FOQOIFMQNQ Q6 IF GIOQOOO; OlOm-bl Ilbbhlh GOO Carbonyl, amldo:

e an ace ne Carbonyl, double bonds; Mesltyl oxide-.- Aceto henone. Benza acetone Formamide- Acetamidm Proplcnamid Butyramlde.

Ether:

Dlethyl ether;

Ether, double bonds:

'Ietramcthyl dlhydroluranm Dlmethyl lnrane Anleole Ether, trl le bond:

Ethybielthler cl dimethyl ethynl o-Nltro phenotole Ether, carbonate:

Beta-methcxy ethyl carbonate Sulfide, double bonds;

'llo hene Proplenltrlle b0 ar nate.

Dlmethyl carbonate Dimethyl carbonate Phossl hau.

rlmethyl phosphate Trlethyl phosphate Trlbutyl phosphate 7 ate. Dlmethyl sulfate H 3 33 33 33 333 3333 33 3 H 3'' 3 3 .333 323333333232 HHHH 333 3"5 33333 "332 a H H More than 2 imilarly cottonseed oil y be extracted with a quantity (four volume, more or less) oi active solvents such as: v

n-Pro lalcohol E 1 ace 1 colate W "si ma Glycol diacetate Triethyl p osphate and many others to obtain immiscible systems that separate into two phases which can be separated by decantation or other methods.

Most of these solvents will also behave similarly with fish oil, linseed oil, tung oil, olive oil and animal fats such as tallow.

In a series of quantitative tests to determine the selectivity of certain liquids for unsaturated components of a glyceride oil, a soy-bean oil having an iodine number of 136 was treated with liquids in the ratio of 1 part of oil to 4 parts of extracting liquid. Extraction was efiected by agitating together the oil and the extracting agent at the temperatures indicated in the following table. They were subsequently allowed to separate into two layers. One layer consisted of oil relatively poor in unsaturates in which was dissolved some of the solvent. The other layer comprised a solvent in which was dissolved oil rich in unsaturates. The layers were then separated and the extracting agent was eliminated by vacuum distillation. Iodine numbers were determlned by the Wijs method. The results are tabulated below:

TABLE Per cent Iodine g number u; Solvent sepafer- Exrafll- Ex- Raflitract nate tract nate Nitroethane 0 28. 3 71. 7 148. 2 130. 3 17. Methyl iormate- 0 l3. 8 86. 2 149. 6 133. 8 15. 12 28. 71. 7 144. 2 132. 9 11. Methyl cellosolve.-. 28 9. 0 91 147. 0 132. 2 14. 70 43. 0 57 138. 0 131. 5 6. Methyl levulinate. 27 85 147. 0 132 5 14. Proplonitrile 0 33. 2 66. 8 145. 5 131. 2 14. e a a are as e Trlmetbyl phosphete. 70 2 90 147. 0 134. 0 13. 1A8 11 89 144.0 132.8 11. Aoetaldeh de.-.---- 0 27.9 72. 1 144.3 131:9 12. Tiretbylp osphete- 0 41 59 142.1 130.0 12. Aoetonyl acetone... 27 2o 80 146. 0 134. o 12. 60 47 53 151. 0 131. 0 10. Acetone (3% mm). 27 41 59 139. 6 132. 8 6. Diacetyl. 0 18 82 145. 0 133. 2 11. Nitromethene 27 6 94 145. 0 133. 5 11. 95 14.3 85.7 143.0 134.5 8. Glycol (1130811316.-.- 65 38 62 141.0 129.7 11. any! 0 late. 8 g s 4 42 125% i m 11. Methyl eellosolve ace 0 .41 59 140.2 130.2 10. Methyl lactate 70 23. 3 76. 7 139. 5 131. 7 9. Ethyl lactate 27 56 44 138.5 130.2 8. Cellosolve- 0 56. 5 43. 5 138. 8 130. 7 8. Eth melee 0 2d 74 140. 1 132.0 8. Acetic anhydrlde 90 51 49 138. 2 131. 0 7. Col to] 125 22.5 77.5 139.0 132.8 6. Propylene glycol--- 27 6 95 139. 0 135. 0 4. Acetic acid 50 62 38 137. 8 133. 8 4. Methyl bntanolone. 0 49 61 137. 0 132. 2 3. ar s a 2 a2 a: mpeno 135.0 3. Ethyl glyeolate...- 77 21 77 138. 0 135. 0 3.

asiaese 5 Linseed oil was similarly extracted with acetic acid with the following results:

Iodine number on mnon 231%,; insoluble Marine oil (menhaden) was extracted with a series of solvents as follows:

Iodine number Solvent Original 5,31%; Insoluble Methyl cellosolve 187.5 208 182 Ethyl acetoacetate and phenol 186- 201 161 Ethyl acetoacetate 186 281 161 Phenol and petroleum ether 184 189 181 Flll'l'llmL 184 206 157 In the example in which ethyl acetoacetate and phenol were employed in admixture, the ratio of the two was ethyl acetoacetate parts, phenol 20 parts.

Where phenol and petroleum ether were employed the ratios of the two ingredients were phenol 1 part, petroleum ether 10 parts, or 1:1 ratio using phenol plus 10% water.

Index of refraction also constitutes a measure for the drying powers of an oil. Samples of a marine oil having an index of refraction of 1.4820 were treated with ethylene chlorohydrin and pyridine to obtain two layers, one consisting of insoluble oil having a lower index of refraction than the original material and the other having a substantially higher index than the original oil. The results are as follows:

Indices of refraction These solvents indicated by the letter M in Table B could'not be used by themselves to effect fractionation of highly unsaturated glycerides from less highly unsaturated ones, because of undue miscibility with both types. However, in many cases it is possible to mix the active solvent with an aliphatic hydrocarbon such as hexane, butane, propane, dodecane, or the like, which is relatively immiscible with the selective solvent. The hydrocarbons tend to pull the saturated glycerides away from the active solvent and permits separation of the oil into two fractions. The ratio of hydrocarbon to active solvent may vary over a broad range, e. g. 1 to 10 parts of hydrocarbon per 1 part of the active solvent. However, good results have been obtained by employment of a ratio of 4 to 1. In general the greater the proportion of hydrocarbon employed, the stronger will be the tendency to pull away the saturated glycerides from the polar solvent.

Similar methods may be employed to effect fractionation of mixtures of saturated and unsaturated fatty acids. These are usually soluble in polar or activesolvents such as are listed above. However, by suflicient admixing of the solvent with a hydrocarbon it is possible to effect separation of free acids into two phases. one consisting essentially of active solvent which is rich in unsaturated acids and the other consisting essentially of hydrocarbon which is rich in saturated acids. This process is illustrated by acids from linseed oil:

Parts by volume Linseed oil acids 200 Petroleum ether (B. P. 30-60 C.) 200 Anhydrous furiural 400 These were agitated together at room temperature and allowed to separate into layers.

The solvents were then distilled off from the two fractions separately under vacuum.

Iodine value of original acid 1'13 Iodine value of acid in hydrocarbon 166 Iodine value of acid in furfural 193 A 30 per cent mixture of linseed oil fatty acids in the same hydrocarbon was agitated with 1 volume of furfuryl alcohol and separated into fractions at room temperature.

Iodine value of original acid 173 Iodine value of acid in hydrocarbon 162 Iodine value of acid in solvent 203 Ethylene glycol diacetate was agitated at room temperature with a 12 per cent by volume mixture of linseed oil fatty acids in petroleum ether, and the mixture was separated into fractions from which the solvents were eliminated.

. Iodine value of original acids 173 Iodine value of acids in hydrocarbon 168 Iodine value of acids in solvent 175 employed in combination with a non-polar hydrocarbon to obtain fractionation of the oil into less saturated and more saturated cuts.

An extension of the foregoing method would involve treatment of mixed fatty glycerides, e. g. linseed oil or soy-bean oil with a selective polar solvent such as furfural or ethyl acetoacetate or the like, to obtain two liquid phases. The phase comprising the solvent and the more unsaturated glyceridescould then be treated by batch or by counter current or concurrent extraction with hexane or other hydrocarbon to pull out additional saturated glycerides, thus leaving a higher concentration of unsaturates in the fraction obtained from the solvent.

The immiscible fraction of oil containing a more fully saturated glyceride after separation from the solvent may be treated in an additional stage with a more sharply selective solvent to remove therefrom additional unsaturated'material.

An example of such procedure would involve initial extraction of soy-bean or similar oil with 'furfural followed by treatment of the immiscible phase with nitroethane to remove therefrom an additional quantity of unsaturated material.

Similarly polar solvents such a: methyl cellosolve acetate which are miscible at all practicable temperatures with glycerides such as occur in tung oil and oiticica oil may be employed in combination with hexane or other open chain hydrocarbons to obtain separation into a hydrocarbon soluble fraction and a fraction soluble in the polar or active solvent. In this process the proportion of hydrocarbon to the polar solvent may vary over a broad range. However, the higher the ratio of hydrocarbon the more selective will be the system.

In some cases where extreme selectivity of the system is not required, a readily miscible solvent such as phenol may be incorporated with a more selective solvent to increase yield of extract. Such system is illustrated by ethyl acetoacetatephenol above described. These ingredients may be employed in a ratio of 1 part of phenol to 4 parts of ethyl acetoacetate.

Separation of the glyceride or acid fractions and the solvents may be effected, as previously stated, by crystallization, vacuum distillation, steam distillation or other methods. A convenient method involves addition of water, which tends to reduce the solubility of the glycerides in the solvent. The water may be employed in an amount suflicient to saturate the solvent or if the solubility of water in the solvent is high it may be added until the glycerides or the free fatty acids separate.

Appropriate variations in the mode of manipulating the fractions obtained by solvent extraction of a glyceride oil would involve further fractionating or splitting one of the fractions, e. g.

the solution of highly unsaturated glycerides, to

ing power may be stream distilled to drive off some of the solvent, or may be chilled, thus causing some of the less soluble (more saturated) glycerides to be separated. This latter fraction can then be recycled.

Manifestly, the highly miscible solvents which can not be conveniently employed by themselves in the fractionation of mixed glycerides can still be employed to extract the glycerides from seed meals and pulp. Afterwards the more selective solvents can be applied to the whole oil after or before'elimination of the initial solvent to separate a highly unsaturated fraction. Ethyl acetoacetate is of particular value in the extraction of fish oils.

It possesses low solvent powers for the break and color constituents of various oils and accordingly by application of it, it is possible directly to dissolve out most of the constituents of the oil, useful in paints and varnishes, to obtain a product which is low in break and color and which dries rapidly to non-tacky films. When warm, it may also be used directly to extract vegetable oils such as linseed oil, or soy-bean oil from the meal or pulp. The following constitutes a specific example of its application to the treatment of raw fish oil, such as sardine or menhaden oils.

Oil in the ratio of one part was contacted in ing water was found to be of a pale green color and to dry practically free of tack. The fish-like odor was substantially less pronounced than in ordinary oil. The residue was of a deep reddish brown color of substantially lower index of refraction and iodine number than the original oil. If dried very slowly and remained permanently tacky. The yield of oil can be increased though with slight impairment of quality by the addition of phenol in considerable portions (15 to 30 per cent more or less). The use of methyl alcohol or ethyl alcohol in 2:1 ratio on the ethyl acetoacetate extract of the raw fish oil produced a' raflinate whose acid number was 0.0 and whose iodine number had increased to the remarkable value of 212.5. This oil was pale green; it had a very bright appearance. The drying test showed the film to be slightly better than raw linseed oil in regard to tack. The test values are as follows:

Iodine Oil value Acid value iis) Combination of ethyl acetoacetate and furfural extraction may sometimes be desirable. For example, raw fish oil (such as menhaden) was ex-. tracted with ethyl acetoacetate at 39 C. and a fraction containing 80% of. the oil was recovered. The product was then extracted with furfural saturated with water in 1:1 ratio, at 20 C. The loss from the product as a result of extraction was only 2 or 3% and the color was materially improved. The results of tests conducted upon the material are tabulated as follows:

Oil Acid value Freeman, filed May 22, 1937, of which the present case is a continuation in part.

The foregoing examples are to be considered merely as illustrative and numerous modifications may be made therein without departure from the spirit of the invention or the scope of the following claims.

The. present application is a division of my copending application Serial No. 251,340, filed January 17, 1939, issuing as Patent 2,200,391,

as of the date of May 14, 1940.

What I claim is:

1. A process of separating mixtures of saturated and unsaturated fatty acids into a plurality of fractions, one of which is relatively rich in, and the other of which is relatively poor in, unsaturates, said process comprising intimately contacting the mixture with a selective polar solvent containing at least one of the groups included in Table A, the number of carbon atoms for each group not being substantially less than the number permissible as determined from the table and not exceeding about 4, the temperature being such that twoJiquid phases are formed, one compris- 8 solvent in which is dissolved the first-mentioned fraction and the other comprising the secondmentioned fraction, in which is dissolved some of the solvent, separating the phases and fural and furiuryl alcohol and the acids treated are from an oil selected from a class consisting of linseed oil and soya bean oil.

STEPHEN E. FREEMAN.