GB770622A - Process for the production of aromatic ketone hydroperoxides - Google Patents

Abstract

Ketone hydroperoxides of formula <FORM:0770622/IV(b)/1> wherein R1 is a hydrogen atom or an alkyl, aralkyl or aryl radical, R2 is an alkyl, aralkyl or aryl radical, or R1 and R2 together form part of a cycloalkyl ring, R3 is an alkyl, aryl or cycloalkyl group, or one of their substituted derivatives, and Ar is an aromatic nucleus which may be further substituted by alkyl, aryl or aralkyl groups, are prepared by contacting a ketone of formula <FORM:0770622/IV(b)/2> in liquid phase at elevated temperatures with gases containing molecular oxygen. The following groups are specified in the above formul : R1 and R2 are methyl, ethyl, propyl, butyl, phenyl, naphthyl, tolyl, or benzyl or together form a part of a cyclopentyl or cyclohexyl ring; R3 is methyl, ethyl, propyl, butyl, phenyl, naphthyl, tolyl, cyclopentyl, cyclohexyl, or benzyl; and Ar is a benzene or naphthalene ring which may be substituted by methyl, ethyl, phenyl, tolyl, or benzyl. The ketone starting material may be used alone or in the presence of an inert diluent such as water or benzene. In the case of water an emulsifying agent such as sodium ricinoleate or lauryl sulphate may be used. The molecular oxygen may be oxygen, or mixtures containing oxygen such as air, and ozone may be present. The rate of input of oxygen is preferably between 0.01 and 1.0 mols. per hour per mol. of starting material. The temperature is preferably between about 80 DEG and 120 DEG C. and the pH of the reaction mixture is between about pH4 and 10. The presence of a free-radical oxidation initiator such as acetyl peroxide, benzyl peroxide, triphenyl methyl peroxide, tert.-butyl peroxide or hydroperoxide, tert.-amyl hydroperoxide, diphenyl methyl hydroperoxide, tetrahydronaphthalene hydroperoxide, methyl cyclohexyl hydroperoxide, cyclohexene hydroperoxide, a : a - dimethyl benzylhydroperoxide, a : a -dimethyl p-methyl or -isopropyl benzyl hydroperoxide, a : a : a 1 : a 1-tetramethyl p - xylylene dihydroperoxide, a : a - dimethyl naphthyl methyl hydroperoxide, hexaphenyl ethane and 2-azo-bisisobutyronitrile in amounts of about 0.1 to 20 per cent by weight of the ketone is advantageous. The preferred initiator is the hydroperoxide formed by oxidation of the same ketone. The hydroperoxides may be separated from the oxidation mixture by fractional distillation at low pressure, by crystallization, by precipitation as its sodium hydroxide solution and neutralizing the alkaline extract with carbon dioxide. The hydroperoxides may be decomposed to give the corresponding phenol. In examples a mixture of m- or p-isopropylacetophenone, calcium hydroxide and 2-azo-bisisobutyronitrile is oxidized by heating to 90 DEG C. and passing oxygen, the oxidation mixture being subsequently extracted with sodium hydroxide solution, the extract saturated with carbon dioxide and extracted with ether, the ether being evaporated to give m- or p-acetyl-a : a -dimethylbenzyl hydroperoxide. The Provisional Specification refers to the use of heavy metal compounds as catalysts in the oxidation process. Specified metals are manganese, cobalt, lead, iron, nickel, copper, vanadium and mercury. Specification 770,623 is referred to.