反应详情

Moreover, WO 97/31883 describes a process for preparing 1,6-hexanediol and ε-caprolactone from a carboxylic acid mixture which comprises adipic acid, 6-hydroxy-caproic acid and small amounts of 1,4-cyclohexanediols and is obtained as a by-product of the oxidation of cyclohexane to cyclohexanone/cyclohexanol with oxygen or oxygen-comprising gases and by water extraction of the reaction mixture, and this mixture is esterified with a low molecular weight alcohol to give the corresponding carboxylic esters, the resulting esterification mixture is freed of excess alcohol and low boilers in a first distillation stage, the bottom product is separated in a second distillation stage into an ester fraction essentially free of 1,4-cyclohexanediols and a fraction comprising at least the majority of the cyclohexanediols, obtaining a fraction comprising essentially 6-hydroxycaproic acid (stage 12) by means of a third distillation stage and cyclizing it to ε-caprolactone in the gas or liquid phase.