GB892631A - Process for the preparation of aliphatic peracids - Google Patents

Abstract

A process for the production of an aliphatic peracid comprises subjecting an aliphatic aldehyde to vapour phase reaction with oxygen in a reactor the surfaces of whose walls are formed of a material which, when subjected to the test hereinafter described, does not cause a reduction of the peracid to normal acid mole ratio in the products to a value which is less than 50% of the ratio obtained under standard defined conditions. The test comprises oxidising the aldehyde in an aluminium reactor of defined construction operated under such conditions as to give a peracid to normal acid mole ratio of at least 10 : 1, but in the presence in the reactor of thin strips of the material being tested in such amount as to double the surface/volume ratio. When a material for coating the reactor surface is being tested it is coated on to aluminium strips. The preferred reactor surface is aluminium, but other suitable ones include polyethylene or various silicones coated on glass. Alternatively, an inert liquid boiling above the reaction temperature may be introduced into the reactor so as to form a coating on the walls; suitable liquids include perfluorinated polyvinyl chloride or trifluoromonochloroethylene polymers. Reaction temperatures of about 80 DEG C.-200 DEG C. are mentioned for the oxidation of acetaldehyde to peracetic acid. The reaction is promoted by back mixing, in the reactor, of the products of reaction with the fresh feed. The oxygen may be pure or diluted. At least 5 mole per cent. of oxygen is preferably used in the feed. The products may be recovered by introducing the reaction products into a cooled column in which they are mixed with the vapour of a solvent for peracetic acid and a solution of peracetic acid in said solvent is withdrawn from the base of the column, while acetaldehyde is removed from a higher point. Specifications 547,333 and 892,632 are referred to.