PRODUCTION OF HYDROXY FATTY ACIDS AND ESTOLIDE INTERMEDIATES

Abstract: A process for the production of hydroxy fatty acids and novel estolide compounds, each of which may be used as lubricants, greases, plasticizers and printing inks, as well as in cosmetics. The estolides are of formula (I) wherein R1 is selected from C6-C16 hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted, such as with one or more hydroxy groups; R2 is independently selected from C2-C17 hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted, such as with one or more hydroxy groups; A is selected from C3-C14 hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted; n is greater than or equal to 1; y is an integer from 3-13; x is 1 or 2; and ... designates a single or double carbon/carbon bond. Formation of these estolides is by catalytic reaction of unsaturated fatty acids, especially DELTA <5> and DELTA <6> unsaturated fatty acids. Following their formation, the estolides may be recovered for subsequent use, or in the alternative, they may be hydrolized to produce hydroxy fatty acids.

Description: Title: Pr-oduction of Hydroxy Fatty Acids and Estolide Znterine-lates . Bacforround of the Invention Field of the Invention Ihis Jjwention relates to hydroxy fatty acids, a process for their production, and estolide -jnterrrediates. ihe hydroxy fatty acids and estolides are useful as lubricants, greases, plasticizers and printing inks, as veil as in cosmetics. Description of the Prior Art Unsaturated fatty acids have been used in the past for the p__ductiαn of ditner acids by a variety of techniques, including clay catalyzed reactions, as reviewed by Johnson [ ■■ Diinerization and Polyπ-2ri2ation," in: Fatty Acids, E.H. Rcyde (ed.), AOCS, (1979), pages 343-352] and Leonard [in: Encyclopedia of Chemical Technology, Ki k-Othmer, John Wiley & Sons, third edition, volume 7, (1979)]-. Depending upon the fatty acid feed, the d__mer acids were produced together with monomer acids, and ranged in structure from acyclic to monocyclic to polycyclic. In accordance with the goals of these prior art processes, reaction conditions were selected to irax-Lmize yields of these dimer acids. No estolides have been reported or identified as products of any of these previous methods. Yamaguchi et al . (Japanese Patent 213,387, (1990)] recently described a process for enzymatic production of estolides from hydroxy fatty acids present in castor oil using lipase. However, such estolides would be composed of esters at the 12 carbon of the fatty acids. Hydroxy fatty acids have also been described, and are useful as . lubricants and greases and in cosmetics. However, there is no domestic ∞m ercial source of hydroxy fatty acids currently available. The hydroxy fatty acids are derived from castor oil which must be iπported. f.jnnarv of the Invention We have now __πvεnted a process for the production of hydroxy fatty acids and novel estolide compounds, each of which may be used as lubricants, greases, plasticizers and printing inks, as well as in cosmetics. The estolides are of the formula (I) : wherein R_ , is selected from C 6 - C lβ hyd_ ** oca_±ons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted, such as with one or more hydroxy groups; R 2 is independently selected from Qj - C 17 hyάroc_arbons which may be saturated or unsa-b-trated, and branched or straight chain, and optionally substituted, such as with one or more hydroxy groups; A is selected from C, - C 14 hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted; n is greater than or equal to 1; y is an integer from 3-13; x is 1 or 2; and ... designates a single or double carbon/carbon bond. Pαrmation of these estolides is by catalytic reaction of unsaturated fatty acids. Following their formation, the estolides may be recovered for subsequent use, or in the alternative, they may be hydrolyzed to produce hydroxy fatty acids. In accordance with this discovery, it is an object of this invention to provide novel estolide cornpounds having utility as lubricants, greases, plasticizers and pr__nting inks. It is a further object of this invention to provide a method of making these estolide coπpounds and also hydroxy fatty acids having utility as lubricants, greases, plasticizers and printing inks, as well as in cosmetics. Other objects and advantages of this invention will became. readily apparent from the ensuing description. Detailed Description Starting roater-Lals for use in the invention include one or a mixture of unsaturated fatty acids of the formula (II) : R-σf=CH-(CH 2 ) z →-D∞ (II) wherein R is selected from C β - C lβ hydroc-trbons which may be saturated or unsaturated, and branched or straight chain, and z is 3-13. Exeπplary unsaturated fatty acid starting materials include tut are not limited to Δ 13 unsaturated fatty acids such as erucic acid (22:1 Δ"), Δ» unsaturated fatty acids such as oleic acid (18:1 Δ») and pa__mitoleic acid (16:1 Δ»), Δ« uι_sat-urated fatty acids such as petroselinic acid (16:1 Δ<), and especially Δ* unsaturated. fatty acids. Without being limityd thereto, preferred Δ» unsaturated fatty acids include 5-doσosenoic acid (22:1 Δ*) , 5,13-docosadienoic acid (22:2 Δ*'i3), 18:1 Δ* fatty acids, and especially 5-eicosenoic acid (20:1 Δ*). The Δ s and other.unsaturated fatty acids are naturally occurring in a variety of plant oils and may be conveniently obtained for use therefrom. Meadowfoam oil, having a high content of Δ S unsaturated fatty acids (total fatty acids composed of approximately 60% 5-eicosenoic acid, 10% 5-docosenoic acid, 19% 5,13-docosadienoic acid, and less than 5% 18:1 Δ' fatty acids) , is particularly preferred as a source of the starting material. However, the practitioner skilled in the art will recognize that other oils may be used as sources, such as pine oils or it-srsh-marigold oils. As starting materials in the reaction of the invention, the unsaturated fatty acids may be provided in substantially pure form or, in the alternative, they may be provided as a _rri_κture or in irtpure form, such as an above-mentioned naturally ciccurring oil subjected to saponification. The novel estolide -Intermediates of this invention are prepared fcy a reaction of one or more of the unsaturated fatty acids, in the presence of a suitable catalyst and water under suitable -t-sarperature and pressure conditions effective to form an estolide of the formula (I): wherein R x is selected from - C lβ hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted, such as with one or more hydroxy groups; R 2 is independently selected from Cj - C 17 hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted, such as with one or more hydrojy groups; A is selected from Cj - C 14 hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and optionally substituted; n is greater than or equal to 1; y is an integer frαn 3-13; x is 1 or 2; and ... designates a single or double cs___bαn/carbαn bond. Preferred estolides include those formed by reaction of the above-mentic-ned Δ* unsaturated fatty acids, and especially Δ« and Δ 5 unsaturated fatty acids. In accordance with the former preferred embod__meπt, the estolides (I) formed are of the foraiula wherein R l f R 2 , A, n, y, x and ... are as described above except that R 2 is selected from C 7 - C 17 hydrocarbons, A is selected from C 3 - C β h_r-drocarbons, and y is an integer from 3-7. Particularly preferred estolides formed from the Δ S and Δ« ur__aturated fatty acids are of the fαπrula wherein R l t R 2 , A, n, y, x and ... are as described above except that R x is selected from C n - C l f hydrocarbons, R 2 is selected from C 10 - C 17 hydroc-irbons, A is selected from C 3 - c 6 hydrocarbons, and y is 3 or 4. Following the reaction, the crude estolide fraction is separated from the catalyst as by filtration, and the water is removed. The estolides may be further purified by distillation to remove the low boiling ironc-ner fraction (urisat_xtrated fatty acids and saturated fatty acids), leaving a residue fraction containiiig estolides and, depending upon reaction conditions, a variable ainount of dimer acids which may also be removed, for example, by ch-X-ratography or distillation. In a preferred embodiment, reaction conditions will be selected such that no or substantially no dimer acids are produced in the course of reaction, with only estolides being formed and the residue fraction comprising substantially pure estolides. As mentioned above, the estolides may be recovered for use without further reaction, or, in the alteπative, the estolides may be hydrolyzed to produce a mixture of fatty acids and hydroxy fatty acids. The fatty acids fanned during hydrolysis are of the fora-tula (III): R 1 -CH χ _ 1 ...CH χ (CH 2 ) y CO0H (III) while the hydroxy fatty acids are of the formula (IV) : OH R 2 -CH-A-COOH (IV) * wherein R_, R_ . , A, y and x are the same as described above. Hydrolysis of the estolides as described generally results in the formation of a plurality of hydroxy fatty acids differing iri the position of the hydroxy group along.the hydrocarbon chain, and in ratios varying with the particular estolide hydrolyzed. For example. upon hydrolysis, estolides formed by the reaction of Δ 5 unsaturated fatty acids predc-D-Lnaπtly yield 6-hydroxy fatty acids, with smaller amounts of 5- and 7-**hydrσxy fatty acids also being formed. A summary of the structure of the estolides formed from reaction of a irurriber of repr-esentative fatty acids, as well as the hydrcoy fatty acids formed upon hydrolysis, is shown in Table I. Conditions for the estolide formation reaction are ideally selected to _r-__r_imize the production of dimer acids, with preferred teπperature and initial pressure ranges of about 230-250* C and about 30-60 psi, respectively. The pressure is maintained at or above the initial pressure during the course of the reaction, and may reach a maximum of about 1000 psi. The co___sntraticns of water and catalyst are advantageously between about 8-12 parts and about 6-8. parts, respectively, per 100 parts of the unsaturated fatty acid starting material. However, the practitioner .skilled in the art will recognize that other conditions and concentrations may be selected at the expense of product yield and purity. -Reactions should be conducted in sealed, stainless steel reactors under a N 2 or other inert gas atmosphere, and with agitation provided, for example, by internal stirrers or external rocking. Particularly preferred reaction conditions and concentrations of reactants are selected such that the estolides formed in the course of the reaction are substantially free of diiner acids. In accordance with this best mode of the invention, about 100 parts of the unsaturated fatty acids are cot-Dined with about 10 parts water and about 8 parts clay catalyst in a reactor, under a N 2 at_mosphere at about 60 psi, and at a temperature of about 250" C. Using these conditions and allowing the reaction to proceed with mixing for about 3 hours, with the pressure reaching 640 psi, reaction yields of 18% (estolides) have been attained from Δ' unsaturated fatty acids. Table I Starting Fatty Acid Estolide Hydroxy Fatty Acid Product Fatty Acid z *2 from Hydrolysis 1) 5-eicosenoic C 1 3 c 14 c 4 * 6-hydroxy eicosanoic* (20:1 ΔS) 3 l4 C 3 5***hydroxy eicosanoic 3 -14 7-hydroxy eicosanoic 2) 5-octadecenoic -12 c 4 * 6-hydroxy cc±adecanoic* (18:1 ΔS) 5-hydroxy octadecanoic 7-hydroxy octadecanoic 3) 5-docosenoic -16 3 C16 C 4* C 16* 6-hydroxy docosanoic* (22:1 ΔS) 3 ;17 5-hydroxy docosanoic 3 c c 1 16 6 ? c 5 : 15 7-hydroxy docosanoic 4) 5,13-docosadienoic -16 6-hydroxy-_-3-docosenoic (22:2 Δ5'i3) 5-hydroxy-13-docosenoic 7-hydro)y-13-docosenoic _-2-hydroxy-5-docosenoic 13-hyd_rexy-5-docosenoic 14-hydroxy-5-docosenoic 5) petroselinic -11 6-hydrαxy octadecanoic* (18:1 Δ«) 7-hydrαxy octadecanoic* 5-hydroxy octadecanoic 8-hydroxy octadecanoic 6) oleic 7 § 9-hydroxy octadecanoic* (18:1 Δ') 7 10-hydroxy octadecanoic* 7 § 7-hydroxy octadecanoic 7 § c 11 8-hydroxy octadecanoic 7 ^ °7 11-hydroxy octadecanoic 7) palπάtoleic 7 cs* 8-hydroxy hexadecanoic* (16:1 Δ») 7 < ** 9 7-hydroxy hexadecanoic 7 °7 9-hydroxy hexadecanoic 8) erucic 11 11 11-hydroxy docosanoic (22:1 Δ13) 11 C 10 C 10 12-hydroxy docosanoic 11 13-hydroxy docosanoic* 11 £ C 1n2 * >8 * 14-hydroxy docosanoic- * Predciminant estolide(s) and/or hydroxy fatty acids formed. -6- Hydrolysis of the estolides to the fatty acids and hydroxy fatty acids may be achieved using conventional splitting techniques or aUali spHtting of fats. Suitable aUcali splitting techniques include, far example, treatment with sodium methoxide, or sodium or potassium hydroxide [see "A.O.C.S. Tentative Method Ca 6b-53", in: Official and Tentative Methods of the American Oil Chemist's Society, third edition, AOCS, Chicago, IL, (1973)]. Other conventional techniques including splitting with steam under pressure are contemplated as being effective. Methyl esters of the estolides and the hydroxy fatty acids, respectively, may also be formed by first treatment of the estolide with αlazctπethane, followed by a second treatment with sodium methoxide in methyl alcohol. A variety of suitable catalysts may be used, particularly clay <-a * t-_-lysts including but not limited to Montmorillonite K 10 clay, bentonite, and Filtrol Grade 13 (Fluka Chemical & Biochemical Co., Ronkonkoma, NY). Example l Ifeadowfoam oil having a composition as described above was obtained from the Oregon Meadowfoam Growers Association (SE. Salem, OR) and split by high pressure steam to obtain the fatty acids. Reactions were run at 250* C in a 0.5-L Mgh-pressure bomb reactor under an initial pressure of 60 psi N 2 . The bomb was loaded with about 20 g Montmorillonite K 10 clay catalyst (Aldrich Chem., Milwaukee, WI), 25 g water, and then about 250 g of Meadσwfoam fatty acids, and plaoed in a rocker to stir the contents during the reaction, which was run for 3 hr. After the reaction had cooled to room te-tperature, the contents were dissolved in hexane (3 x 100 ml) and renewed from the reactor. R-anσyal of the clay was accomplished by filtration of the reaction mixture on a Buchner funnel using Whatman (Maidstone, England) #54 filter paper (fast, hardened) . The filtrate was then dried over MgS0 Λ to remove residual water, and filtered -through a B-tchner funnel with a medium porosity glass frit. The remaining filtrate was composed of a mixture of estolides in combination with moncroeric co-rponents (ΔS uiαsaturated fatty acids) and diacids. Initial purification of the filtrate for the removal of a substantial portion of the moncmeric ccmponents was achieved by distillation with heating to 160* C at 0.3 Torr in an Aldrich Kugelrchr distillation apparatus, yielding a residue of estolides and dimer acids. The yield far the reaction was 21% [calculated as % residue * 100% x residue wt/(residue wt + distillate wt)]. Following purification, the distillate was found to be coπposed of 62% estolides as detennined by HPLC analysis [Veazey, J. Am. Oil Chem. Soc , 63:1043 (1986)] coupled with an evaporative light-scattering detector [Barnhorst et al. , paper E2 presented at the Annual American Oil Chemists' Society Meeting, Cincinnati, OH, May 1989]. It is understood that the foregoing detailed description is given merely by way of illustration and that modifications and variations may be made therein without departing from the spirit and scope of the invention.

Claims: We claim: 1. An estolide cαiyound of the formula: wherein R x is selected frαn C^ - C lβ hyd__ocarbons which may be saturated or unsaturated, and branched or straight chain; R_, is independently selected from c 10 - C 17 hydrocarbons which may be saturated or unsaturated, and branched or straight chain; A is selected from C_ - C β hydrocarbons which may be saturated or unsaturated, and branched or straight chain; y is 3 or 4.; n is greater than or equal to 1; x is 1 or 2; and ... designates a single or double carton/carbon bond. 2. A ccrnpcund as described in claim 1, wherein A is aQ hydrocarbon which may be saturated or unsaturated, and branched or straight chain, and n is one. 3. A cornpound as described in claim 2, wherein R x and R 2 are C 14 , straight chain, saturated hydrocarbons. 4. A coπpcund as described in claim 1, wherein A is a C s hydrocarbon which may be saturated or unsaturated, and branched or straight chain, and n is one. 5. A ccmpound as described in claim 1, wherein A is a C 3 hydrocarbon which may be saturated or unsaturated, and branched or straight chain, and n is one. 6. A compound as described in claim 1, wherein one or both of R x and R 2 are substituted with one or more hydroxy groups. 7. A cαipound as described in claim 1 which is substantially pure. 8. A method of making estolide cαipounds corπprising the steps of: a. reacting one or a mixture of unsaturated fatty acids of the formula (I): R-Of=CH-(CH 2 ) z -O0OH (I) wherein R is selected from C 6 - C lβ hydrocarbons which may be saturated or unsaturated, and branched or straight chain, and z is an integer from 3-13, in the presence of water and a suitable catalyst and under suitable conditions effective to form one or more estolides of the formula (U): wherein R_. is selected fr m C 6 - C 1 6 hydrocarbons which may be saturated or -rnsatorated, and brεinched or straight chain; j> is -ttJependently selected from Cj - C 17 hydrocarbons which may be saturated or unsaturated, and branched or straight chain; A is selected from C, - C 14 hydrocarbons which may be saturated or unsaturated, and branched or straight chain; y is an integer from 3-13; n is greater than or equal to l; x is l or 2; and ... designates a single or double carbon/carbon bond; and b. separating said estolides from said catalyst and said water. 9. A method as described in claim 8 wherein z is an integer from 3-7; R_> is independently selected from c 7 - C 17 hydrocarbons which may be saturated or unsaturated, and branched or straight chain; A isaC, - C β hydrocarbon which may be saturated or unsat-urated, and branched or straight chain; and y is an integer from 3-7. 10. A method as described in claim 9 wherein z is 3 or 4; R is selected from C n - C 14 hydrocarbons which may be saturated or unsaturated, and branched or straight chain; x is selected from C-- - C lβ hydrocarbons which may be saturated or unsaturated, and branched or straight chain; R 2 is independently selected from C 10 - C 17 hydrocarbons which may be saturated or unsaturated, and branched or straight chain; A is a C 3 - C β hydrcx-arbαn which may be saturated or unsaturated, and branched or straiφt chain; and y is 3 or 4. 11. A method as described in claim 10, wherein R is a C_, hydrocarbon, z is 3, and R- and Rj are C_.., hydrocarbons, A is a C, hydrocarbon, and n is 1. 12. A method as described in claim 10, wherein R is a c. 6 hydrocarbon, z is 3, and R_> and R 2 are C 1S hydrocarbons, A is a hydj-ocarbon, and n is l. 13. A method as described in claim 8, further cx_rπprising the steps of hydrolyzing said estolides from said step (b) to produce a reaction -mixture cαtprising fatty acids and hydrojy fatty acids, said fatty acids being of the foππula (III) : Rι-CH j _-ι••.Ci CH 2 ) y O0OH (III) and said hydroxy fatty acids being of the foππula (IV) : OH I R 2 -CH-A-C0OH (IV) 14. A method as described in claim 13, wherein z is an integer from 3-7; R j is independently selected from C 7 - C 17 hydrocarbons which may be saturated or ur_3aturated, and branched or straight chain; A is a C 3 - C β hydrocarbon which may be saturated or unsaturated, and branched or straight chain; and y is an integer from 3-7. 15. A method as described in claim 14 wherein z is 3 or 4; R is selected from C_ x - c tt hydrocarbons which may be saturated or unsaturated, and branched or straight chain; R- i≤ selected from C u - C : « hydrocarbons which may be saturated or unsaturated, and branched or straight chain; R 2 is independently selected frαn C 10 - C 17 hycirocarbons which may be saturated or unsat-urated, and branched or straight chain; A is a C j - C β hyd__oca-- * bon which may be saturated or unsaturated, and branched or straight chain; and y is 3 or 4. 16. A method as described in claim 15, wherein R is a C 14 hydrocarbon, z is 3, and R x and R 2 are C 14 hycϊrocarbons, A is a C 4 hydrocarbon, and n is l. 17. A method as described in claim 15, wherein R is a C lβ hycϊ- ca____on, z is 3, and R__ and R 2 are C lβ Ais aC, hydrocarbon, and n is 1. 18. A method as described in claim 8, wherein said catalyst is clay. 19. A method as described in claim 8, wherein said step of reacting is at a terrperature between about 230 - 250 β c and an initial pressure between about 30 and 60 psi, and the concentration of said catalyst is between about 6 - 8 parts and the concentration of said water is between about 8 - 12 parts per 100 parts of said Δ 5 unsaturated fatty acids. 20. A msthod as described in claim 19, wherein said terrperature is about 250* C, said pressure is about 60 psi, said catalyst concentration is about 8 parts and said water concentration is about 10 parts per 100 parts of said Δ 5 unsaturated fatty acids. " 21. A method as described in claim 8, wherein said step of reacting is conducted in a sealed reactor with agitation. 22. A method as described in claim 8, wherein said unsaturated fatty acids are selected from the group consisting of 5-eicosenoic acid, 5-docosenoic acid, 5,13-docosadienoic acid, 18:1 ΔS fatty acids, and iαixtures thereof. 23. A method as described in claim 8, further comprising the step of purifying said estolides from said step (b) .

Inventors: BURG DOUGLAS A, ERHAN SELIM M, KLEINAN ROBERT, BURG, DOUGLAS, A., ERHAN, SELIM, M., KLEINAN, ROBERT
Applicants: BURG DOUGLAS A, ERHAN SELIM M, KLEINAN ROBERT, BURG, DOUGLAS, A., ERHAN, SELIM, M., KLEINAN, ROBERT
Application year: 1992
Main classification: C07C69
IPC codes: C07C69