GB572963A - Conversion of vinyl type halides to aldehydes or ketones - Google Patents

Abstract

Vinyl-type halides containing at least 4 carbon atoms and a vinylic grouping wherein neither of the carbon atoms is tertiary, which halides are free from alcohol, ether and ester groups, are converted into ketones or aldehydes by reaction with water in the presence of a strong oxy-acid. The vinyl grouping may comprise part of an iso or normal alkyl chain which can be attached to a cyclic radical or comprise part of an alicyclic structure. The compounds may contain halogen other than that attached to the vinylic carbon. Preferably, no tertiary vinylic carbon atoms are present. The hydrogen other than that in the vinyl groups may be substituted by alkyl, aralkyl, carbocyclic, and/or heterocyclic groups which may be further substituted. The preferred halogens are bromine, chlorine and iodine. Suitable vinyl-type halides are the following, and their homologues, analogues and substitution products: <FORM:0572963/IV/1> Depending upon the structure of the vinyltype halide, the products are ketones, aldehydes, aldehyde-ketones, poly-ketones or halogenated carbonyl compounds. The strong oxyacids include mineral acids and other strong oxy-acids which act as mineral acids, for example, H2SO4, HPO3, H2S2O7, H4P2O6, H3PO3, H3PO4, H4P2O7, aromatic sulphonic acids such as benzene sulphonic, and halosulphonic acids such as chlor- and bromosulphonic. The halide may be treated with the aqueous acid, with anhydrous acid followed by water or with the acid and sufficient water for only partial conversion, additional water being added later. Preferably, 80-90 per cent aqueous sulphuric acid is used at about 20-40, and possibly up to 60 DEG C., being added slowly to the halide in the proportion of about 1 mol. for each vinyl grouping present, the contact time being one hour. The product is diluted, preferably with water, to an acid concentration of 25-75 per cent, and the carbonyl compound recovered as by fractionation at ordinary or reduced pressure, if desired, after neutralization. In the recovery of methyl ethyl ketone where 2-chlorbutene-2 is the halide used, the reaction mixture is steam distilled in a stripping column, whereby 40-50 per cent sulphuric acid, suitable for concentration and re-use, is also recovered. The hydrogen chloride formed in the initial reaction is recovered for use in chlorine manufacture. Inert organic diluents, e.g. hydrocarbons, halogenated hydrocarbons and esters, may be present during the reaction. In examples: (1) 5 mols. of 84 per cent aqueous sulphuric acid are added to 4 mols. of 2-chlorbutene-2, and contacted for 1 hr. at 28 DEG C., the mixture then being diluted to 60 per cent acid and stripped with steam to recover methyl ethyl ketone; (2) the molar ratio is 1 : 1, contact time 1/2 hr. at 31 DEG C., and dilution to 25 per cent acid; (3) conditions are as in (1) except that the molar ratio is 5 : 3.18, and the chloride is diluted to 50 per cent weight with a synthetic octane; (4) a continuous reactor is used comprising a packed column at 30 DEG C., 7 1/3 moles of halide being continuously introduced at the bottom to 8 1/2 mols. of acid at the top to give a contact time of 1 hr.