Patent ID: 8183411

Claim:
A process, comprising: a) oxidizing cyclohexane with molecular oxygen or mixtures of molecular oxygen and gases which are inert under the reaction conditions to give a reaction mixture which comprises cyclohexyl hydroperoxide, cyclohexanol, cyclohexanone, cyclohexane, 6-hydroxycaproic acid, 6-hydroxycaproic acid, 5-formylvaleric acid, and at least one α,ω-dicarboxylic acid having from four to six carbon atoms; b) separating the reaction mixture from a), after adding water, into an organic phase comprising cyclohexane and the cyclohexane compounds, and an aqueous phase comprising the carboxylic acids; c) catalytically hydrogenating the aqueous phase from b); d) reacting the carboxylic acids present in the aqueous phase with an alcohol comprising from 1 to 10 carbon atoms to give the corresponding carboxylic esters, to yield an esterification mixture; and e) distilling out a 6-hydroxycaproic ester from the esterification mixture from d), to obtain at least one 6-hydroxycaproic ester, wherein the catalytically hydrogenating in c) comprises hydrogenating 5-formylvaleric acid to 6-hydroxycaproic acid in the presence of a catalyst, which comprises at least one metal selected from the group consisting of ruthenium, nickel, cobalt, rhenium, and copper, and wherein the hydrogenating in c) is performed at a temperature of from 100 to 200° C. and a pressure of from 1 to 100 bar.