Methods and Compositions for Preparing Triglycerides Containing Fatty Acid Vicinal Diester Functionality

Abstract

A method for producing a triglyceride including fatty acids with vicinal diesters: (a) providing a triglyceride including fatty acids with epoxide groups; (b) reacting the epoxide groups with carboxylic acid salts under basic conditions to produce a triglyceride including fatty acids with vicinal ester/alkoxides; (c) protonating the vicinal ester/alkoxides to produce a triglyceride including fatty acids with vicinal ester/alcohols; and (d) reacting the vicinal ester/alcohols with carboxylic acids under acidic conditions to produce a triglyceride including fatty acids with vicinal diesters.

Claims

1. A method for producing a triglyceride including fatty acids with vicinal diesters, the method comprising: (a) providing a triglyceride including fatty acids with epoxide groups; (b) reacting the epoxide groups with carboxylic acid salts under basic conditions to produce a triglyceride including fatty acids with vicinal ester/alkoxides; (c) protonating the vicinal ester/alkoxides to produce a triglyceride including fatty acids with vicinal ester/alcohols; and (d) reacting the vicinal ester/alcohols with carboxylic acids under acidic conditions to produce a triglyceride including fatty acids with vicinal diesters.

2. The method according to claim 1, wherein the method minimizes production of fatty acids with tetrahydrofuranic diesters to less than 5 wt % of the total fatty acids.

3. The method according to claim 1, wherein the fatty acids with epoxide groups of (a) include linoleic acids and linolenic acids of which double bonds have been epoxidized.

4. The method according to claim 1, wherein the carboxylic acid salts of (b) include a cation which is an alkali metal or a quaternary ammonium salt.

5. The method according to claim 1, wherein the triglyceride of (a) is an epoxidized soybean oil or an epoxidized algal oil.

6. The method according to claim 1, wherein the product triglyceride of (d) has an ISO viscosity within a range of 40-80 centistokes.

7. The method according to claim 6, wherein the triglyceride of (a) is an epoxidized triglyceride including less than 30 wt % total linoleic and linolenic fatty acids and more than 40 wt % oleic fatty acids.

8. The method according to claim 1, wherein the product triglyceride of (d) has a pour point less than 5 C.

9. The method according to claim 8, wherein the triglyceride of (a) is an epoxidized triglyceride including less than 10 wt % saturated fatty acids having more than 14 carbon atoms.

10. An industrial fluid comprising the triglyceride produced according to the method of claim 1 and another functional component.

11. The industrial fluid according to claim 10, wherein the functional component is selected from the group consisting of pour point depressant, anti-wear additive, base stock, diluent, extreme pressure additive, and antioxidant.

12. A method for producing a triglyceride including fatty acids with vicinal diesters, the method comprising: (a) providing a triglyceride including fatty acids with epoxide groups; (b) reacting the epoxide groups with first carboxylic acids in the presence of a catalyst to produce a triglyceride including fatty acids with vicinal ester/alcohols; and (c) reacting the vicinal ester/alcohols with second carboxylic acids under acidic conditions to produce a triglyceride including fatty acids with vicinal diesters.

13. The method according to claim 12, wherein the second carboxylic acids are different from the first carboxylic acids.

14. The method according to claim 12, wherein the reaction (b) is heated.

15. The method according to claim 12, wherein the method minimizes production of fatty acids with tetrahydrofuranic diesters to less than 5 wt % of the total fatty acids.

16. The method according to claim 12, wherein the fatty acids with epoxide groups of (a) include linoleic acids and linolenic acids of which double bonds have been epoxidized.

17. The method according to claim 12, wherein the triglyceride of (a) is an epoxidized soybean oil or an epoxidized algal oil.

18. The method according to claim 12, wherein the product triglyceride of (c) has an ISO viscosity within a range of 40-80 centistokes.

19. The method according to claim 18, wherein the triglyceride of (a) is an epoxidized triglyceride including less than 30 wt % total linoleic and linolenic fatty acids and more than 40 wt % oleic fatty acids.

20-23. (canceled)

24. A method for producing a triglyceride including fatty acids with vicinal diesters, the method comprising: (a) providing a triglyceride including fatty acids with epoxide groups, the fatty acids including less than 30 wt % total linoleic and linolenic fatty acids and more than 40 wt % oleic fatty acids; and (b) reacting the epoxide groups with carboxylic acids under acidic conditions to produce a triglyceride including fatty acids with vicinal diesters.

25-36. (canceled)

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention provides improved methods for preparing triglycerides containing fatty acid vicinal diester functionality. In a first embodiment, a method according to the invention comprises: [0009] (a) providing a triglyceride including fatty acids with epoxide groups; [0010] (b) reacting the epoxide groups with carboxylic acid salts under basic conditions to produce a triglyceride including fatty acids with vicinal ester/alkoxides; [0011] (c) protonating the vicinal ester/alkoxides to produce a triglyceride including fatty acids with vicinal ester/alcohols; and [0012] (d) reacting the vicinal ester/alcohols with carboxylic acids under acidic conditions to produce a triglyceride including fatty acids with vicinal diesters.

[0013] An example of this method as it is applied to a triglyceride including linoleic acid is shown below:

##STR00002##

[0014] In this method, the formation of THF diesters is avoided in fatty acids containing double bonds (e.g., linoleic and linolenic acids) since their epoxides are not subjected to acidic conditions which trigger formation of THF diesters. In certain embodiments, the method minimizes production of fatty acids with THF diesters to less than 5 wt % of the total fatty acids, and preferably less than 1 wt %.

[0015] The reactivity of carboxylic acid salts in this approach is influenced by variations in ion-pairing between the carboxylate anion and the cation employed. Thus, the influences of various cations such as different alkali metals and quaternary ammonium salts on reaction efficiencies will be evaluated to determine the optimum cation and solvent to be used in this reaction sequence.

[0016] In a second embodiment, an improved method for preparing triglycerides containing fatty acid vicinal diester functionality comprises: [0017] (a) providing a triglyceride including fatty acids with epoxide groups; [0018] (b) reacting the epoxide groups with first carboxylic acids in the presence of a catalyst to produce a triglyceride including fatty acids with vicinal ester/alcohols; and [0019] (c) reacting the vicinal ester/alcohols with second carboxylic acids under acidic conditions to produce a triglyceride including fatty acids with vicinal diesters.

[0020] An example of this method as it is applied to a triglyceride including linoleic acid is shown below:

##STR00003##

[0021] This reaction scheme affords a number of advantages. There is no need to basify and then acidify reaction mixtures. The method can produce vicinal esters with the same or different vicinal ester groups (different groups typically leading to desired lower pour points).

[0022] Any suitable catalyst can be used in the first reaction. For example, some categories of catalysts that may be used include tertiary amines, tertiary phosphines, and quaternary ammonium or phosphonium salts. In certain embodiments, the first reaction is also heated.

[0023] Again, the formation of THF diesters is avoided in fatty acids containing double bonds.

[0024] The present invention also provides improved fatty acid compositions for preparing triglycerides containing fatty acid vicinal diester functionality. When introducing vicinal diester functionality to unsaturated fatty acids containing relatively low percentages of linoleic and linolenic acids (e.g., total of linoleic and linolenic less than 30 wt % of the total fatty acids, and preferably less than 20 wt %) and relatively high amounts of oleic acid (e.g., more than 40 wt % of the total fatty acids, and preferably more than 50 wt %), production of THF diesters can be minimized in two ways. One approach is to use the suggested approach involving reaction of their epoxides with carboxylic acid salts under initial basic conditions as described above.

[0025] Another approach is to utilize the reaction of their epoxides with carboxylic acids under acidic conditions. In this approach, the small amounts of THF diesters that would be formed may not adversely influence the performance of vicinal diester type triglycerides. If desired, these triglycerides can be formulated with small amounts of anti-oxidants to prevent THF diester oxidation.

[0026] In certain products, for example lubricants, there is a need for triglycerides having ISO viscosities in the 40-80 centistoke range. The ISO viscosities of vicinal diester type triglycerides are directly dependent on their linoleic acid/oleic acid ratios whereby the greater this ratio, the higher their ISO viscosities. Thus, vicinal diester type triglycerides derived from commodity oils such as soybean oils, that have relatively high linoleic acid/oleic acid ratios, have relatively high ISO viscosities. Hence, using fatty acids containing high percentages of oleic acid will facilitate preparation of decreased ISO viscosity triglycerides.

[0027] Another desired characteristic of vicinal diester-containing triglycerides in certain products, for example lubricants, is that they have pour points that are as low as possible, for example less than 5 C. Pour points in these type triglycerides are inversely dependent on the quantity of saturated fatty acids having more than 14 carbon atoms. Thus, preferred fatty acid compositions are those that also contain minimal amounts of saturated fatty acids having more than 14 carbon atoms (e.g., less than 10 wt % of the total fatty acids, and preferably less than 5 wt %).

[0028] Fatty acids possessing this combination of desired compositional properties may conveniently be derived from algal sources. However, they can also be derived from other renewable feedstocks.

[0029] In summary, to prepare triglycerides containing vicinal diester functionality derived from fatty acids containing a range of linoleic and linolenic acids and not generate THF diester functionality, the present invention provides a reaction sequence that starts with the reaction of fatty acid epoxides with relatively non-expensive carboxylic acid salts under basic conditions. Alternatively, triglycerides containing vicinal diester functionality can be prepared from fatty acids contain low to nil amounts of linoleic and linolenic acid by reacting fatty acid epoxides with carboxylic acids under basic or acidic conditions. Fatty acids containing low quantities of saturated fatty acids are also desired starting materials to produce vicinal diester-based triglycerides with low pour points.

[0030] The triglycerides produced according to the invention may be useful for preparing a wide variety of different products. In certain embodiments, the products are industrial fluids. The industrial fluids may be useful as engine oils (typically two cycle, four cycle, Wankel, and turbine type engines), hydraulic fluids, drive oils, metal working fluids, greases, general lubricants, brake fluids rock drilling fluid and the like.

[0031] The industrial fluids can contain another functional component in addition to the modified triglyceride of the invention. For example, the functional component may be selected from the group consisting of pour point depressant, anti-wear additive, base stock, diluent, extreme pressure additive, and antioxidant.