Method for the synthesis of diacids or diesters from natural fatty acids and/or esters

Abstract

The invention relates to a process for the synthesis of diacids or diesters of general formula ROOC—(CH2)x—COOR, in which n is an integer between 5 and 14, R is either H or an alkyl radical of 1 to 4 carbon atoms, from natural long-chain monounsaturated fatty acids or esters including at least 10 adjacent carbon atoms per molecule of the general formula CH3—(CH2)n—CHR1—CH2—CH═CH—(CH2)p—COOR, in which R is H or an alkyl radical with 1 to 4 carbon atoms, R1 is either H or OH, and n and p, which are equal or different and are indices between 2 and 11. The method comprises: during a first step, converting the natural fatty acid or ester by pyrolysis or by ethenolysis, into a ω-monounsaturated fatty acid or ester of the general formula CH2═CH—(CH2)m—COOR, in which m is equal to p or p+1, depending on the nature of the processed fatty acid/ester and the conversion used; during a second step, submitting the product thus obtained to a metathesis or homometathesis reaction for obtaining a compound of the general formula ROOC—(CH2)m—CH═CH—(CH2)m—COOR, or cross-metathesis with a compound of formula R2OOC—(CH2)r—CH═CH—R3, in which R2 is either H or an alkyl radical front with 1 to 4 carbon atoms, r is either 0 or 1 or 2 and R3 is H, CH3 or COOR2, thus defining a cyclic or molecule or not, in order to obtain an unsaturated compound of the general formula ROOC—(CH2)m—CH═CH—(CH2)r—COOR2, and during a third step, converting the unsaturated compound into a saturated compound by hydrogenation of the double bond.

Dependencies are inferred from the claim text.