NEW METHOD FOR THE OZONOLYTIC SYNTHESIS OF HIGH MELTING DICARBOXYLIC ACIDS AND OXO-ACIDS
The present disclosure pertains to improved methods of preparing high melting dicarboxylic acids or oxo-acids (e.g., carboxylic acid/aldehydes) by ozonolysis of their esters. For example, the present disclosure provides methods for preparing brassylic acid by way of the ozonolysis of erucic acid ester, the method comprising the steps of converting the erucic acid to an ester, performing ozonolysis on the ester, and converting the resulting brassylate ester product to brassylic acid.
1 . A method for preparing a high melting point dicarboxylic acid from a monounsaturated or polyunsaturated fatty acid, comprising the steps of:
(a) converting the fatty acid to a C 3-12 fatty acid ester;
(b) performing ozonolysis with oxidative work-up on the C 3-12 fatty acid ester to form the dicarboxylic acid ester and carboxylic acid by-product; and
(c) converting the dicarboxylic acid ester to the dicarboxylic acid product.
2 . The method according to claim 1 , wherein the fatty acid has a melting point above 15° C., e.g., above 20° C., or above 25° C., or above 30° C., e.g., up to 60° C.
3 . The method according to claim 1 , wherein the dicarboxylic acid product has a melting point above 60° C.
4 . The method according to claim 1 , wherein the fatty acid is selected from erucic acid, palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, gondonic acid, paullinic acid, nervonic acid, stearidonic acid, gamma-linolenic acid, eicosapentaenoic acid, arachidonic acid, docosatetraenonic acid, linolenic acid, linoleic acid, and linoleaidic acid; and optionally, wherein the product dicarboxylic acid is selected from brassylic acid, azelaic acid, adipic acid, glutaric acid, pimelic acid, undecanedioic acid, and pentaundecanedioic acid.
5 . A method for preparing brassylic acid from erucic acid, comprising the steps of:
(a) converting erucic acid to a C 3-12 erucic acid ester,
wherein R is a C 3-12 alkyl;
(b) performing ozonolysis on the C 3-12 erucic acid ester to form the corresponding brassylic acid ester and nonanoic acid,
and
(c) converting the brassylic acid ester to brassylic acid (e.g., by aqueous hydrolysis)
6 . The method of claim 5 , wherein R is C 3-10 alkyl.
7 . The method of claim 5 , wherein R is selected from isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-amyl, n-hexyl, n-heptyl, 2-ethylheptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, isodecyl.
8 . The method of claim 1 , wherein the step (b) ozonolysis comprises (1) treating the fatty acid ester with gaseous ozone in a carrier gas in a flow reactor, followed by (2) continuous quenching of the flow reactor product stream under oxidative conditions.
9 . The method of claim 8 , wherein the step (b)(1) is carried out in a co-current flow reactor.
10 . The method of claim 8 , wherein the fatty acid ester of step (a) is introduced into the reactor of step (b)(1) as an aqueous emulsion consisting of the neat erucic acid ester and aqueous solution.
11 . The method of claim 8 , wherein the fatty acid ester of step (a) is introduced into the reactor of step (b)(1) as the neat fatty acid ester.
12 . The method of claim 8 , wherein step (b)(2) comprising continuously mixing the output stream from the reactor of step (b)(1) with a quenching solution comprising an oxidizing agent.
13 . The method of claim 1 , wherein step (a) is carried out by reacting the fatty acid with the corresponding C 3-12 alcohol (R—OH) or C 3-12 alkene in the presence of an acidic catalyst.
14 . The method of claim 1 , wherein the product stream from step (b) consists essentially of the dicarboxylic acid ester, the carboxylic acid by-product, and any unreacted fatty acid ester, or carried over fatty acid.
15 . The method of claim 1 , wherein the product stream from step (b) and/or step (c) does not contain any reduction products.
16 . A method for preparing a high melting point oxo-carboxylic acid from a monounsaturated or polyunsaturated fatty acid, comprising the steps of:
(a) converting the fatty acid to a C 3-12 fatty acid ester;
(b) performing ozonolysis with reductive work-up on the C 3-12 fatty acid ester to form the oxo-carboxylic acid ester and aldehyde by-product;
and
(c) converting the oxo-carboxylic acid ester to the oxo-carboxylic acid product;
wherein the formation of ozonide intermediate of the ozonolysis step (b) is conducted in a flow reactor.
17 . The method according to claim 16 , wherein the method further comprises the step of isolating the aldehyde by-product from the crude product, or partially purified product, of step (b) or of step (c).
18 . A method for preparing a high melting point dicarboxylic acid from a monounsaturated or polyunsaturated fatty acid, comprising the steps of:
(a) converting the fatty acid to a C 3-12 fatty acid ester;
(b) performing ozonolysis with reductive work-up on the C 3-12 fatty acid ester to form the oxo-carboxylic acid ester and aldehyde by-product;
(c) removing the aldehyde by-product;
(d) oxidizing the oxo-carboxylic acid ester to form the dicarboxylic acid ester; and
(e) converting the dicarboxylic acid ester to the dicarboxylic acid-product;
optionally, wherein the formation of ozonide intermediate of the ozonolysis step (b) is conducted in a flow reactor.
19 . (canceled)
20 . (canceled)
21 . (canceled)
22 . The method of claim 1 , wherein the fatty acid has a melting point of up to 60° C.
23 . The method of claim 1 , wherein the product stream from step (b) and/or step (c) does not contain any nonanal, nonanol, 13-oxotridecanoic acid, 13-oxotridecanoate esters, 13-hydroxytridecanoic acid, or 13-hydroxytridecanoate esters.