Patent GB-424885-A (GB)
Title: Improvements in or relating to the manufacture of derivatives of unsaturated acids
IPC: C07C67/327
Filed: 1933-08-03
Abstract: Lower alkyl (including hydroxyalkyl and alkoxyalkyl) esters and nitriles of a -b -unsaturated monocarboxylic aliphatic acids are manufactured by heating, in the vapour form, to a temperature considerably in excess of their boiling points, the lower alkyl esters (including the mono - esters of polyhydric alcohols or their monoalkyl ethers), nitriles or amides of mono- or dialkylglycollic acids in which the a -hydroxyl group is esterified with a mono- or dibasic acid or a monoalkyl ester of a dibasic acid, the said acid or ester being volatile at the reaction temperature or yielding decomposition products volatile at that temperature.  The acids with which the a -hydroxy group is esterified may be monobasic acids, e.g. acetic acid, dibasic acids, e.g. phthalic, sulphurous, sulphuric or carbonic acids, or alkyl hydrogen carbonates, or sulphites, e.g. methyl hydrogen carbonate or sulphite.  The starting materials in these cases may be prepared from the mono- or dialkylglycollic esters, nitriles or amides by the action of an acid chloride or anhydride, of phosgene (to produce the symmetrical carbonates), of methyl chloroformate (to produce the unsymmetrical methyl carbonates) or of thionyl chloride or methyl chlorosulphite (to produce the symmetrical and unsymmetrical sulphites respectively). Alternatively, the corresponding a -halogenated compounds may be treated with, for example, sodium acetate.  The heat treatment which is preferably performed at about 400--600 DEG  C., may be carried out by passing the vapours, if desired together with an inert diluent gas or vapour, e.g. nitrogen or carbon dioxide, through a heated tube, which may be suitably packed, e.g. with quartz or with catalytic packing materials, e.g. silica gel or graphite.  Examples describe the manufacture of: (1) methacrylic nitrile from a -acetoxyisobutyronitrile; (2) methyl methacrylate from methyl a -acetoxyisobutyrate (obtained by acetylating methyl a -hydroxyisobutyrate); (3) methacrylic nitrile from N - acetyl - a  - acetoxyisobutyramide (obtained, together with a -acetoxyisobutyronitrile, by heating acetone cyanhydrin with acetic anhydride); (4) acrylic nitrile from a -acetoxypropionitrile; (5) methyl acrylate from methyl a -acetoxypropionate (obtained by the action of acetic anhydride on methyl lactate); (6) ethyl acrylate from ethyl a -acetoxypropionate; (7) methyl methacrylate from methyl a -benzoyloxyisobutyrate (obtained by the interaction of methyl a -hydroxyisobutyrate, benzoyl chloride and pyridine); (8) ethyl acrylate (and ethyl lactate) from crude di-(a -carboethoxyethyl) sulphite; (9) methyl methacrylate (and some methyl a -hydroxyisobutyrate) from di-(a -carbomethoxyisopropyl) carbonate (obtained by passing phosgene into a mixture of methyl a -hydroxyisobutyrate and pyridine); (10) methacrylic nitrile from di-(a -cyanoisopropyl) carbonate (obtained by treating acetone cyanhydrin with phosgene and pyridine); (11) methyl acrylate from di-(a -carbomethoxyethyl) carbonate (obtained by treating methyl lactate with phosgene and pyridine); (12) acrylic nitrile from di-(a -cyanoethyl) carbonate (obtained by treating acetaldehyde cyanhydrin with phosgene and pyridine); (13) methyl acrylate from methyl (a -carbomethoxyethyl) carbonate (prepared by adding methyl chloroformate to a mixture of methyl lactate and pyridine); (14) acrylic nitrile from methyl (a -cyanoethyl) carbonate (obtained by treating acetaldehyde cyanhydrin with methyl chloroformate and pyridine); (15) b -methoxyethyl methacrylate from -b  methoxyethyl a -hydroxyisobutyrate (obtained by treating acetone cyanhydrin with the monomethyl ether of ethylene glycol in the presence of sulphuric acid and acetylating the product); the product may be polymerized by warming with benzoyl peroxide; (16) methyl acrylate from methyl (a -carboethoxyethyl) phthalate (obtained by boiling ethyl lactate with methyl hydrogen phthalate).