PROCESS FOR PRODUCTION OF 1, 12-DODECANEDIOIC ACID

摘要

1393845 Production of 1,12-dodecanedioic acid E I DU PONT DE NEMOURS & CO 2 July 1973 [3 July 1972] 31419/73 Heading C2C 1,12-Dodecanedioic acid is obtained by reductively coupling the adduct of cyclohexanone and hydrogen peroxide with a reducing agent at 20‹ to 100‹ C. and separating the desired acid from the oxidized reducing agent and by-products of the coupling reaction; the reductive coupling reaction being effected with an aqueous solution maintained at pH 1 to 6 and containing ferrous iron combined with a chelating agent, the latter containing at least one carboxylic acid group and at least one basic nitrogen-containing group selected from aminoid and heteroaromatic nitrogen, the carboxylic acid and basic nitrogencontaining groups being separated by at least one but no more than two carbon atoms. The oxidized coupling agent may be regenerated by catalytic hydrogenation (e.g. 0-35À2 Kg./cm.2 gauge pressure H 2 at 25-100‹ C. over a catalyst comprising one or more of Pd, Pt, Rh and Ru) and recycled to the coupling reaction. The cyclohexanone -H 2 O 2 adduct, viz. the peroxyhemiketal of cyclohexanone, is obtained by reaction of H 2 O 2 with cyclohexanone, a cyclohexanone-cyclohexanol mixture or a cyclohexanone-cyclohexanol-cyclohexane mixture or by air oxidation of cyclohexanol. Exemplified chelating agents are nitrolotriacetic acid,α-benzyl andα-isobutyl-nitrilotriacetic acids, iminodiacetic acid, nitrilotripropionic acid, nitrilopropionic-diacetic acid, ethylenediaminetetraacetic acid, N-(2-picolyl)- iminodiacetic acid and picolinic acid. Example (2-9)a describes the preparation and isolation of cyclohexanone -H 2 O 2 adduct and caproic acid is the major by-product of the reductive coupling reaction.