Preparation of dimethyl dodecanedioate in two steps was studied. The first step is the formation of methoxycyclohexyl peroxide by reaction of cyclohexanone with hydrogen peroxide and methanol in the presence of acid catalyst.
The second is the dimerization of the resulting methoxycyclohexyl peroxide through the action of iron (II) sulfate to obtain the dimethyl dodecanedioate. In the first step, sulfonic acid in 0.01010.015 mol per mol of cyclohexanone is used as the catalyst. In the second step, the resulting methoxycyclohexyl peroxide can be used for the dimerization without purification. Various iron (II) salts, such as iron (II) sulfate, iron (II) ammoniumsulfate and ferrous chloride, are effective as the reducing reagents. The reaction can be conducted at a temperature below 10°C. Water should be used in excess in the redox reaction, if it is desired to obtain branched dibasic acid dimethyl esters. Cyclopentanone, cycloheptanone and 2-methylcyclohexanone gave the corresponding dibasic acid dimethyl esters, respectively.
