Patented June 6, 1944 2,350,583

UNITED STATES PATENT office

DRYNG OS Theodore F. Bradley, Stamford, Conn., assignor to American Cyananid Company, New York, N. Y., a corporation of Maine No Drawing. Application February 8, 1941, Seria No. 378,060 3 Claims. (C. 260-405.6) This invention relates to improvements in dry may be used for the isomerization of any unsat ing oils and the higher fatty acids which they urated fatty acid or acids the molecules of which contain. The invention includes the prepara contain at least two non-conjugated double tion of such oils by isomerizing polyunsaturated bonds. In most cases the isomerization treat higher fatty acids to bring about a relatively high ment will be applied to mixed fatty acids only content of conjugated double bonds therein foll Some of which are polyunsaturated as this is the lowed by esterification of the isomerized acids forn) in which these acids are found in vegetable with a polyhydric alcohol. The invention also and fish oils of relatively high iodine values. It includes a new and improved method of isomeriz is an important advantage of the invention, how ing polyunsaturated fatty acids as Well as cer 0. ever, that it can be applied with success to fatty tain new drying oils prepared therefron, acid mixtures containing relatively low percen It is known that the drying properties of poly tages of non-conjugated, polyunsaturated fatty unsaturated higher fatty acids, winen employed acids, as is the case in soya bean fatty acids, as in the form of triglycerides, oil-modified alkyd well as to the more highly polyunsaturated fatty resins and the like, are influenced by the posi 5 acid mixtures such as those of linseed oil. tions of their double bonds with respect to each My isomerization treatment is especially other. If these double bonds are in conjugation adapted for improving the drying properties of (i. e. Separated by only one single bond) the oil the polyhydric alcohol esters of the fatty acid has better drying properties than a similar oil mixtures obtained from such vegetable oils as lin having an equal number of non-conjugated 20 seed oil, SOya bean oil, chia seed oil, perilla oil, double bonds. Thus, for example, tung oil dries poppy seed oil, cottonseed oil, sunflower seed oil faster than linseed oil because the three double and the like as well as the polyunsaturated fatty bonds of the eleostearic acid found in tung oil acids of fish oils, and other polyunsaturated are in conjugation whereas the double bonds of fatty acids of 18 or more carbon atoms. As a the linoleic and linolenic acids of linseed oil are 25 practical matter the oils from which the fatty not. It is a principal object of the present in acids are obtained should have a relatively high vention to provide a relatively quick and inex iodine value, at least on the order of 110-130, as pensive method of isomerizing polyunsaturated otherwise there are not sufficient polyunsaturated higher fatty acids to bring the double bonds acids present to warrant the treatment. It thereof into conjugation so that the polyhydric 30 should also be noted that there is no advantage alcohol esters thereof will have improved drying in applying my isomerization process to eleo properties. stearic acid, or to oils such as tung oil or oiticica, I have found that the double bonds of poly oil which contains large quantities of polyun unsaturated higher fatty acids can be brought saturated acids having double bonds that are into conjugation within a few hours by heating 35 already in conjugation, although the treatment an aqueous solution of the soaps thereof with of such acids is not excluded from the invention excess alkali in a pressure vessel at temperatures in its broadest aspects. Thus, for example, I above about 200° C. and under the corresponding have heated a mixture of 75 parts by weight of autogenic pressures. I have found that by heat tung oil acids, 75 parts of potassium hydroxide ing the acids at these temperatures in the form 40 and 100 parts of distilled water in an autoclave of a solution of their soaps in water the iso at 225-230° C. for 2.5 hours and liberated the re merization or rearrangement of the double bonds suiting isomerized fatty acids from their potas proceeds much faster than would otherwise be sium soaps. The resulting amber colored acids the case, and an equilibrium favoring a relative were partly liquid at room temperature, where ly high content of conjugated double bonds is 45 as the original acids were crystalline, and frac reached in from one to three hours. The most tionation of the isomerized acids by distillation favorable temperature range appears to be from at 250-300° C. under 1 mm. pressure followed by 200° to 250° C., for above this range excessive analysis of the fractions showed that the degree losses of the acids by polymerization may OCCur. of triple conjugation characteristic of eleostearic Insofar as I have been able to determine, my 50 acid had been substantially reduced while cor invention is perfectly general in character and responding quantities of acids having only dou 2,850,588 ble conjugation had been formed. While this have been isomerized to this extent exhibit faster constitutes further proof that the conditions ob and better drying properties as well as heat taining during the heating step brought about bodying characteristics than are possessed by the equilibrium favoring double conjugation, ester original oils from which these acids were ob fication of the isomerized tung oil acids with tained, and since the isomerization equilibrium . glycerine did not give as good a drying oil as the can be attained rapidly in ordinary equipment Original tung oil. this improvement is relatively inexpensive. In many cases it is feasible to subject higher When my isomerization treatment is applied fatty acid mixtures having a relatively low Con to the fatty acids of linseed oil and to dehydrated tent of polyunsaturated fatty acids to a prelim castor oil fatty acids, I find that the resulting inary treatment that will separate out the more fatty acid mixtures have very similar properties. highly saturated fatty acids such as stearic acid, By preparing the esters of the isomerized fatty palmitic acid and the like. Thus, for example, acids from these two sources with glycerine, the crude fatty acids obtainable by saponifica pentaerythritol and dipentaerythritol I have ob tion of soya bean oil, upon refrigeration at about S tained new drying oils which contain about 40% 4 to 12 below zero, centigrade, for 24 hours will of esterified octadecadienic acids in which the crystallize out substantial quantities of stearic two double bonds are in conjugation. These oils and palmitic acids, which can be removed by fill have excellent drying properties, and are in tration, and the percentage of doubly unsatu ed as specific features of the present inven rated fatty acids in the remaining oil is of course O increased substantially. . The invention will be illustrated in greater de The content of fatty acids having conjugated tail by reference to the following specific exam double bonds can also be increased by vacuum ples. The results obtained in these examples distilation of the isomerized fatty acid mixtures. were evaluated by the spectroscopic method re I have found that the acids in which conjugation ferred to in volume 37 of the Biochemical Jour has occurred have slightly higher boiling points na, pages 138-141 (1937) and described in great at reduced pressures than the corresponding non er detail by the present applicant in Industrial conjugated acids, so that fractions rich in con and Engineering Chemistry, volume 32 (1940), jugated acids can be separated by this method. page 963. By this means it was possible to make Ordinarily a flash distillation is preferred, as con 30 quantitative determinations of the content of siderable polymerization of the conjugated acids doubly, triply and quadruply conjugated higher is encountered if they are maintained at ele fatty acids in fatty acid mixtures within very wated temperatures for too long a time. narrow limits of error. It should be understod, Another feature of the invention which is im however, that while these examples may describe portant from a commercial point of view resides 35 in detail some of the more specific features of the in the direct treatment of glyceride oils them invention, they are given primarily for purposes selves by my alkali isomerization process. When of illustration and the invention in its broader such triglycerides as soya bean oil, linseed oil, aspects is not limited thereto. perilla oil and the like are charged into an auto In Examples 2, 3, 4 and 7 some of the isom clave and heated with an aqueous solution of an erized fatty acids have been described by name. alkali the oil is immediately saponified and the It is quite possible, however, that the conjugated soaps of its fatty acids are formed. When the double bond systems of these acids may be one solution contains an excess of alkali over that or two carbon atoms removed from the positions necessary to saponify all the fatty acids and suf assigned, and therefore these examples should cient water to dissolve the resulting Soaps it be regarded as indicative of the results obtained is unnecessary to carry out the saponification as a rather than as proof of the exact structural for separate step, but the autoclave may be directly mulas of these compounds. heated to 200-250 C. and the contents main Eacample 1 tained at these temperatures until conjugation of the double bonds of the fatty acids is effected. 75 parts by weight of linseed fatty acids, 75 After the isomerization of the fatty acids has parts by weight of 100% potassium hydroxide been effected by the above described or similar and 100 parts by weight of water. Were charged processes, drying oils of improved characteristics into a stainless steel bomb-type autoclave fastened are obtained by esterifying the isomerized acids in an electrically heated chamber mounted on with a polyhydric alcohol. Any alcohol of this 55 a rocking device to provide continuous agitation. class having three or more esterifiable hydroxy The degree of heating was thermostatically con groups may be used for this purpose, such as trolled and recorded by a recording pyrometer. glycerol, pentaerythritol or dipentaerythritol. The mixture was heated with agitation to 225 The process of isomerizing fatty acid mixtures C. in 45 minutes, after which it coasted to 240 . containing polyunsaturated higher fatty acids to C. but dropped rapidly again to 225 C. where bring the double bonds thereof into conjugation it was held for 5 hours. The autoclave was followed by esterification with a polyhydric alco then opened and the soft soap and alkali dis hol is a new and commercially feasible method of solved in an excess of distilled water and de preparing synthetic drying oils of improved dry composed by agitation with excess hydrochloric ing properties, and constitutes one of the most acid at the boiling point. The liberated fatty important features of my invention. acids were again treated with hydrochloric acid It should be understood that conjugation of all to insure complete hydrolysis of the soaps, after the double bonds present in polyunsaturated which the product was again washed with dis higher fatty acids is not usually obtained by the tilled Water and dried, process of my invention. The point of equilib 70 The refractive index of the product was 1.4782 rium. between the conjugated and non-conju at 25 C. as compared with the value of 1.4690 gated acids seldom exceeds 50%, and therefore of the linseed fatty acids before the alkali treat only about half of the denic or polyenic acids ment. When analyzed for doubly and triply con of the oils are isomerized. However, the poly jugated double bonds by determining the ultra hydric alcohol esters of fatty acid mixtures that s violet absorption spectra in 0.2%-5% cyclo 2,850,588 3 hexane solutions the product was found to Con The formation of a conjugated acid with four tain 34.6% of 9,11-octadecadienic acid and 7.66% double bonds and a trace of a five double bonded of 10,12,14-octadecatrienic acid or conjugated acid distinguishes this from the preceding isomers of these. batches and is due to the fact that many fish oils . 28 parts by weight of the isomerized fatty acid (unlike most vegetable oils) contain substantial mixture was reesterified by heating with 10.2 amounts of the more highly unsaturated acids. parts of 95% glycerine in an atmosphere of car When esterified with a small excess of glycerine bon dioxide at 215-220 C. for 6 hors. The the isomerized fish oil acids formed a triglyceride product was a clear yellow oil which air dried having excellent drying properties. An alkyd overnight when mixed with driers and flowed out O resin prepared by heating together 30 parts of On tin panels. Similar films hardened within a phthalic anhydride, 19 parts of glycerine and 56 few hours when stoved at 100 C. parts of the isomerized acids at 220 C, for 3.5 Eacample 2 hours, dried rapidly at 90° C. When dissolved in mineral spirits and flowed on tin panels. The 100 parts by Weight of soya bean fatty acids, 5 dried film had a frosted appearance similar to 75 parts of potassium hydroxide and 110 parts of that obtained in tung oil formulations, which water were charged into the autoclave described constituted further proof of conjugation of the in Example 1 and heated with agitation at 225 double bonds. C. for 2.5 hours. Analysis of the fatty acids be Eaccimple 5 fore and after the isomerization gave the follow 20 ing results: It is known that castor oil fatty acids can be dehydrated by heating at about 280° C., and that 9,11-octadecar 0,12,14-octaa 7. the resulting product contains about 15-30% of 25°C ydenie Vivoviv acid decatrienicacid conjugated double bonds in the form of octa 25 decadienic-9,11-acid-1. The following example Per cent Per cert shows that the content of conjugated double Before treatment------464 05 0.165 bonds can be greatly increased by applying the After treatment------14676 20.2O 330 principles of the present invention. 75 parts by Weight of dehydrated castor oil Samples of the isomerized fatty acid mixture 30 fatty acids, 75 parts by weight of lithium hy were esterified with glycerine and with penta droxide and 100 parts of water were charged into erythritol by heating them at 215-225 C. with the autoclave of Example 1 and heated with agi a 5% excess of the alcohol over that necessary tation. The temperature was raised to 220° C. in to form the neutral ester. The drying properties 45 minutes and held at 220-225 C. for three of the triglyceride oil were considerably better hours. The soaps were then recovered, hydro than those of soya bean oil, which dries slowly lyzed with HCl and water, washed free from min to a soft film, while the pentaerythritol ester had eral acid and dried Over anhydrous calcium even better drying properties than the tri chloride. The refractive inde of the acids before glyceride. the treatment was n.60s–14706; after the Eacample 3 40 treatment it was 1.4734. The recovered light 75 parts by weight of linseed fatty acids, 75 amber-Colored acids were distilled at 1-2 mm, of parts of 100% sodium hydroxide and 125 parts mercury yielding an almost water-white product of water were heated at 220-225 C. under 150 of n=1.4731 in 93% yield. Analysis of the 170 lbs. per sq. in... gage pressure for three hours alkali-treated, distilled acids by determining and then cooled, dispersed in water, and treated their absorption spectra showed them to contain with hydrochloric acid as before. The sodium 41.7% of conjugated double bonds as compared soap was somewhat harder than the potassium with 26.0% determined for the original acids by soap of Example i and a little more difficult to the same method. hydrolyze, but otherwise the results were similar. Eacample 6 The dried isomerized fatty acids had a refrac 5 tive index of 1.4803 and contained 41.0% of 9,11 In all the foregoing examples sufficient alkali octadecadienic acid-1 and 8.2% of 10,12,14-octa was used to form water-soluble soaps of the un decatrienic acid-l or conjugated isoners thereof. saturated fatty acids. The following example shows that isomerization is not obtained when Eacample 4 s this condition is not observed. The autoclave of Example 1 was charged with 100 parts by weight of fish-oil fatty acids (a. 100 parts by weight of inseed fatty acids, 120 product known commercially as Neo-Fat #19 parts of Water and only 5 parts of sodium hy acids) and 75 parts by weight of lithium hy droxide, which was just enough to form sufficient droxide were charged into the autoclave of Ex 60 Soap to emulsify the excess fatty acids in the ample 1 together with 100 parts of water. The water. This batch was heated in the autoclave batch was heated at 215-220 C. for 3.5 hours at 220 C. for three hours and then hydrolyzed after which the product was acidified, washed, With acid, Washed and recovered in the usual and the fatty acids recovered in the usual man manner. The refractive index of the dried acids ner. Analysis showed the materials before and 65 was 1.4690, which was identical with that of the after treatment to contain: starting material, from which it was apparent that no conjugated unsaturation had been de 9,11-octade- 0,12,14- Conjugated veloped. octadeca- acid with . declinic rienic 4 double Eacample 7 acid bonds The content of Conjugated somers in the alkali Per cent Perce Per ce. Before treatment. . . 4797 3.3 .7 0.14 isonerized fatty acids of my invention can be After treatment.--- 1.4906 23.20 8.0 2.30 still further increased by vacuum distillation. s Samples of the products of Examples 3 and 4 were 4. 2,850,588 disted at 1 mm. of mercury absolute pressure tinued baking, both oils cured to Water-resistant and the. following cuts obtained: films. r TABLE I Product of Ecample 3

-Octadecanoic acid

Brown cuid and white sold.----- White solid------Water white liquid------Light yellow liquid.------Brown tar------|------TABLE II Product of Eacample 4.

In Octadecanoe acid Materia Frt as Description 9,11-denic 0,2,4sEii thanMore 3 Original.----,------14797 Amber liquid...... 23.2 s suit to 756C 10 1440 Sri as a a a as a C- a a - 8.0 23 2nd cut 175-195 56 1.4656 Solid----...-- } 3.9 265 0.33 3rd cut 95-20°C. 34 .4691 Lenoacid- 25. ... O 0.84 4th cut 200-20°C. 4, 1.4975 Yellow liquid------20.4 62 Residue.------16------Brown tar------

These tables show that a product containing Eacample 9 5 to 10% more doubly conjugated fatty acids can be obtained by separating the higher boiling Oil modified alkyd resins were made from rep fatty acids from those of lower boiling point by 35 erizationresentative by drying heating oil togetheracids before 56 parts and after by weight isom simple distillation. The relatively large quanti of the acid, 29.6 parts of phthalic anhydride and ties of tar indicate that much better and more 18.8 parts of glycero, efficient results are obtainable when pressures considerably lower than 1 millimeter of mercury This mixture was heated in an atmosphere of are employed with a corresponding reduction in 40 carbon dioxide at 180-230 C, for 3.5 hours until the distillation temperature and the amount of the acid number of the product was about 29. polymerization. Continuous distillation of the Four resins were prepared in this manner hav alkali isomerized fatty acids in a molecular still, ing the following characteristics: for example, under a vacuum of 2 to 3 microns absolute mercury pressure will result in more Resin Wiscosity complete separation of the various acids and in No. Fatty acid used Aof solids SSis less loss by polymerization.

Eacomple 8 - Linseed...... 34 "fao The second and third cuts of Table of Exam 50 ge inseed, Example ... 28 . - ple7, amounting to 78% of the total, were con i.EAiyirampa. 8 bined. 40 parts by weight of the mixture were heated with 4 parts of glycerine at 215 C. With These resins were dissolved in approximately continuous agitation while maintaining an at an equal weight of mineral spirits, flowed on tin mosphere of carbon dioxide to avoid discoloration. panels, and stoved for half an hour without the After 5 hours the acid number of the batch was addition of a drier. Resin 2 was found to set up 25.3. Heating was then continued for an addi faster than resin 1 and resin 4 set faster than tional 1.75 hours whereupon a light-colored oil resin 3, with better through dry and less tack. was obtained having an acid number of 23.25. It is evident, therefore, that isomerized fatty This was heated to 220-240° C. for 20 minutes in 60 acids prepared by the methods of the present order to remove free acid, after which the acid invention are well suited for use in the prepara number was 7.8 and the refractive index at 25 C. tion of drying resins. prepara Was 1.4875. 10 gram samples of the resulting synthetic Eacample'10 drying oil were mixed with 0.8 cc. of a drier con 65 883 parts by weight of linseed fatty acids, iso taining, 5% Pb and 0.5% Co. These samples merized and distilled by the method described were flowed out on tin panels, two of which Were in Example 3 and containing 31.4% higher fatty air dried while two more were baked at iO0 C., acids having singly conjugated double bonds and both in comparison with similar panels coated 7.3% of acids having triply conjugated double with KVO linseed oil containing similar amounts 70 bonds, were esterified with 141 parts by weight of of drier. The synthetic oil containing the ison dipentaerythritol by heating at 200-205 C, for erized fatty acids was found to have a faster 6.75 hours. The crude esterification product initial set than the natural oil on air drying, while had an acid number of 17.9 which, after two ex on the baked panels it seemed at first to be more 75 tions with anhydrous ethanol, was reduced tacky than the natural oil but finally, after con O -

2,850,588 S This ester was tested for gelation in compari very slight whitening when immersed in distilled son with a dipentaerythritol ester of ordinary un Water. isomerized linseed acids, washed twice with an This application is a continuation-in-part of hydrous ethanol, and also with a commercial tri my copending application, Serial No. 363,495, glyceride ester of dehydrated castor oil fatty filed October 30, 1940. acids, 10 g. samples of the three synthetic oils What claim is: . . in test tubes were prepared in an oil bath, the 1. A method of producing fatty acids capable temperature of which was raised to 250 C. in of forming polyhydric alcohol esters of improved one hour and thereafter maintained at 250' C. drying properties from a mixture of fatty acids The results obtained are shown in the following O having an iodine number of at least 110 and a table: substantial content of unsaturated higher fatty acids which contain at least two non-conjugated Time at double bonds, which comprises heating a reac Material 250° C. Wiscosity tion mixture consisting of a solution of Soaps 5 thereof and an excess of alkali in Water in the Hour absence of an added alcohol in a closed chamber Isleted inseed dipentaerythritol 3 Firm gel. x for several hours attemperatures of 200-250° C. Linseed dipentaerythritol ester------. 5.5 Z22.7 poises. and under the corresponding autogenic pressure, Dehydrated castor oil triglyceride------. 5.5 U-627 poises. whereby isomerization of said unsaturated higher 20 fatty acids takes place and also a Certain amount From the foregoing results it is evident that of polymerization, and then separating the acids the dipentaerythritol ester of the isomerized line of varying boiling points from the polymers by seed oil fatty acids, due to its extreme poly vacuum distillation at pressure not substantially functionality and conjugated unsaturation, sets greater than 1 mm. of mercury absolute pressure. up much faster than the corresponding ester of 25 2. A method of producing fatty acids capable ordinary linseed oil fatty acids, and that a much of forming polyhydric alcohol esters of improved more completely polymerized product is obtained. drying properties from soya bean fatty acids Eacample 11 w which comprises heating a reaction mixture con Linseed oil fatty acids were isomerized by stir sisting of a solution of soya bean fatty acid soaps 30 and an excess of alkali in water in the absence ring together 100 parts by weight of the acids, of an added alcohol in a closed chamber for Sevr 100 parts of water, and 25 g. of 85% potassium eral hours at temperatures of 200-250° C. and hydroxide until a Soap paste was formed and under the corresponding autogenic pressure, heating in an agitated autoclave at 225°. C. for whereby isomerization of the more highly un 3.75 hours. The soaps were then hydrolyzed with 35 saturated fatty acids thereof takes place together hydrochloric acid at the boiling point of the aque with a certain amount of polymerization and ous Solution and the fatty acids were separated, then separating the acids of varying boiling washed and dehydrated. The acids were then points from the polymers by vacuum distillation found to contain 33.1% of doubly conjugated and at pressures not substantially greater than 1 mm. 11.5% of triply conjugated acids, whereas the 40 of mercury absolute pressure. original material had contained 1.81% and 3. A method of producing fatty acids capable 0.253% respectively. . . of forming polyhydric alcohol esters of improved 62 parts of these acids were mixed with 10.1 drying properties from linseed fatty acids which parts of dipentaerythritol and heated with agita comprises heating a reaction mixture consisting tion in an atmosphere of carbon dioxide. The 45 of a solution of linseed fatty acid soaps and an temperature was carried to 180° C. in one hour, excess of alkali in water in the absence of an then to 200° C. during the second hour and main added alcohol in a closed chamber for several tained at this point for 5 hours longer, when the hours at temperatures of 200-250° C. and under acid number was found to be 11.3. The ester the corresponding autogenic pressure, whereby was then extracted twice with anhydrous eth 50 anol, recovered and dried. It had an acid num isomerization of the more highly unsaturated. ber of 2.1, viscosity of Y (Gardner) and color of fatty acids thereof takes place together with a 4. (Hellige). certain amount of polymerization and then sep Upon addition of driers containing 0.5% arating the acids of varying boiling points from Pb-0.05% Mn+0.005% Co as metal to oil and the polymers by vacuum distillation at pressures flowing out on a tin plate the ester was medium not substantially greater than 1 mm, of mercury set in one hour, had a very slight tack for the absolute pressure. next 4 hours, and was tack-free in 6 hours. . TEODORE, BRAOLEY. After air drying for 24 hours it showed only a