GB570668A - Conversion of vinyl type halides to aldehydes or ketones - Google Patents

Abstract

Vinyl-type halides are converted into aldehydes or ketones by contacting their vapours in the presence of water vapour and at an elevated temperature with a solid hydration agent comprising a mineral oxyacid or an oxyacid which acts as a mineral acid. Suitable halides include those specified in Specification 572,963 and also those wherein the carbon atoms of the vinylic grouping are tertiary while the products are similarly aldehydes, mono- or poly-ketones, aldehyde-ketones, or halogenated derivatives thereof. Specified conversions are 2-chlorbutene-2 to methyl ethyl ketone, 1-brompropylene-1 to propionaldehyde, 2-chlorpropylene-1 to acetone, 1,3-dichlorpropylene-1 to b -chlorpropionaldehyde, isocrotyl chloride to isobutyraldehyde, vinyl bromide or chloride to acetaldehyde, 2-chlorhexene-1 to methyl butyl ketone, and 1-chlorhexene-1 to hexaldehyde. The mineral oxy-acids include H2SO4, H3PO4, H4P2O6, H4P2O7, H3PO3, H4P2O5, HPO3, H3PO2 and H3ASO4. Oxy-acids which act as mineral acids are benzene sulphonic acid, its homologues, analogues and substitution products. Mixtures of these acids with mineral acid salts such as acid phosphates or sulphates may be used. These acid catalysts are preferably employed in admixture with or incorporated on the surface of a solid silicious or similar absorbent such as silica gel, alumina, charcoal, fuller's earth, clays, kieselguhr and partially hydrated silicates and silicic acid compounds. The temperature of reaction is generally 200-400 DEG C. and pressures usually atmospheric. An excess of the halide may be used to give an anhydrous mixture of products from which recovery of carbonylic products and of anhydrous hydrogen halide is facilitated. Allyl-type halides may be present in the starting material, but preferably not above 25 per cent. In the production of methyl ethyl ketone from 2-chlorbutene-2, a phosphoric acid catalyst is preferred at about 200-300 DEG C. At a total feed rate of 20 gram mols. of reactant per litre of catalyst per hour, maximum conversion is obtained with a molar ratio of water to chlorbutene of about 2 : 1 although a ratio of 0.6 : 1 gives a higher yield per litre of catalyst per unit time. The ketone is recovered from the product by diluting with water to give an HCl concentration well below 20 per cent, and obtaining a ketone-water azeotrope by fractionation. In examples: (1) 2-chlorbutene-2 and water in molar ratio of 1 : 2 are separately vaporized and passed through a tube having a preheater section and containing a solid catalyst containing orthophosphoric acid. The tube is heated in an electric furnace to an average temperature of 228 DEG C. and the products are scrubbed with water to reduce the HCl concentration so that methyl ethyl ketone is recoverable by distillation; (2) the water to chlorbutene molar ratio is 0.6 : 1 and average temperature of the solid phosphoric acid catalyst 230 DEG C.; (3) isocrotyl chloride and steam in molar ratio of 1 : 4 are similarly converted to isobutyraldehyde; (4) 1-hydroxy-2-chlorbutene-2 and steam in molar ratio of 1 : 3 are converted to hydroxy methyl ethyl ketone using the same catalyst at 280 DEG C.; (5) 1-chlor-and 2-chlor-propylene-1 are similarly reacted to yield propionaldehyde and acetone respectively. The best yield of the former is obtained at the highest temperature employed, 250 DEG C., with a water to halide ratio of 3 : 1 and total feed rate of just above 10 gram mols. per litre of catalyst per hour.