Hydroxy fatty acid synthesis
Inventors
Cermak, Steven C • Isbell, Terry • Lowery, Benjamin A
Assignees
United States, Represented By Secratery Of Agriculture AS • US Department of Agriculture USDA
Publication Number
US-11680224-B2
Publication Date
2023-06-20
Expiration Date
2041-11-04
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Abstract
The invention relates to methods for the synthesis of hydroxy fatty acids from unsaturated fatty acids via epoxidation and catalytic hydrogenation.
Core Innovation
The invention provides a method for synthesizing hydroxy fatty acids from unsaturated fats via a two-step chemical process. The first step involves peracid epoxidation of the unsaturated fat, producing epoxidized fatty acids. The second step is catalytic hydrogenation of the epoxidized fatty acid using a palladium or platinum catalyst in the presence of a catalytic amount of an organic acid under pressurized hydrogen atmosphere. This method yields good quantities of hydroxy fatty acids with minimal formation of ketone by-products.
The problem addressed arises from the heavy reliance on castor oil as the almost exclusive natural source of hydroxy fatty acids. Castor oil production faces various agronomic and human health challenges, making domestic production in the U.S. unrealistic. Previous efforts to develop alternative domestic sources such as lesquerella have not succeeded commercially, due to risks associated with establishing new crops. Furthermore, known epoxidation and hydrogenation methods either involve stoichiometric reducing agents unsuitable for industrial scale or fail to effectively limit ketone by-product formation. There is thus a need for new methods to synthesize hydroxy fatty acids from readily available oils at costs below current castor oil import prices.
Claims Coverage
The patent contains one independent claim that addresses the synthesis of mono hydroxy fatty acids using a catalytic process in a pressurized container.
Method involving reacting epoxidized fatty acid with organic acid and palladium or platinum catalyst in pressurized hydrogen atmosphere
The method comprises reacting at least one epoxidized fatty acid or epoxidized fatty acid ester in a solvent with an organic acid and a palladium or platinum catalyst in a hydrogen atmosphere inside a pressurized container to obtain at least one mono hydroxy fatty acid.
Use of specific organic acids
The method uses organic acids selected from acetic acid, oxalic acid, trifluoroacetic acid, trichloroacetic acid, or tribromoacetic acid, with oxalic acid emphasized as a preferred organic acid.
Catalyst specifications
The catalyst used is palladium on carbon or platinum on carbon, with palladium on carbon preferred. The palladium equivalents are specifically between about 0.0020 and 0.021 equivalents per equivalent of epoxidized fatty acid, with about 0.0030 equivalents mentioned.
Pressure and temperature conditions
The synthesis is performed under pressures ranging from about 14 psi to about 1100 psi, preferably from about 160 psi to about 1000 psi hydrogen, and at temperatures from about 20° C. to about 180° C.
Control of by-products
The method produces hydroxy fatty acids along with ketone fatty acid by-products, with ketone content in the reaction product controlled to less than about 18%.
Solvent and substrate details
The method excludes certain solvents such as n-butyl propionate containing 1% sulfuric acid, ethanol, petroleum ether containing 1% acetic acid, anhydrous propionic acid, and glacial acetic acid, with ethyl acetate preferred. The epoxidized fatty acid used has more than 7 carbons, and examples include those obtained from various plants e.g., sunflower, safflower, soybean, and others.
The claim collectively protects a specific catalytic process for synthesizing mono hydroxy fatty acids from epoxidized fatty acids, emphasizing the use of certain organic acids and palladium or platinum catalysts under pressurized hydrogen, controlled product composition, specific solvent exclusion, and reaction conditions to improve yield and reduce by-products.
Stated Advantages
The method results in good yields of hydroxy fatty acids with minimal formation of ketone by-products.
The process uses existing commodity oilseed crops as starting materials, providing an alternative domestic source of hydroxy fatty acids that can be produced below current castor oil import prices.
The catalytic hydrogenation using palladium catalyst with a catalytic amount of organic acid enables rapid and selective reduction of epoxides to mono-hydroxy esters.
Documented Applications
Production of hydroxy fatty acids for industrial use, including lubricants, greases, cosmetics, and as raw materials for nylon production.
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