| 摘要 |
a ,a -Dimethylbenzylhydroperoxide is made by reacting isopropylbenzene with molecular oxygen at elevated temperatures not exceeding the boiling temperature of the isopropylbenzene, preferably between 65 DEG and 115 DEG C., in the presence of a transition metal the concentration of which dissolved in the reaction mixture does not exceed that concentration of the same catalyst which decomposes 1/20 of the peroxide content of a mixture of 15 parts by weight of a ,a -dimethylbenzylhydroperoxide and 85 parts by weight of isopropylbenzene at 80 DEG C. within 45 hours. Transition metals are defined as those which are capable of changing their valency and which are oxidation catalysts for organic compounds those specified being iron, cobalt, nickel, copper, lanthanum, lead, thallium, manganese and cerium, the latter being especially suitable. The metals are preferably applied as compounds soluble or dispersible in isopropylbenzene, e.g. stearates, palmitates, oleates and naphthenates, the latter being preferred. Oxides of the metals may be used although soluble only with difficulty in the reaction medium, e.g. PbO, Pb2O3, Pb3O4 and PbO2. Mixtures of the catalysts may be used. Tables are provided showing the maximum concentration of metal permissible and the effect on product yield with changes in catalyst concentration, low concentrates favouring high yields. The catalyst concentration may be increased during the course of the reaction. Diluents, e.g. benzene, may be present. Advisably the reaction is completed within a short time, the unreacted isopropylbenzene being returned after separation of the hydroperoxide. Vigorous agitation of the reaction mixture is an advantage. In examples, isopropylbenzene is treated with oxygen at temperatures ranging from 80 DEG to 100 DEG C. in the presence of manganese, cerium, copper, lead, iron or nickel naphthenates, lead oxide, lead dioxide and a mixture of lead oxide and dioxide. |
