Patent GB-647208-A (GB)
Title: Preparation of unsaturated acid esters
Filed: 1947-07-28
Abstract: An ester, prepared by reacting an aliphatic polyhydric alcohol and an aliphatic unsaturated monobasic carboxylic acid having conjugated double bonds, one of such bonds being in conjugation with the carbonyl group of the acid (see Group IV (b)), typical examples of which are glycol disorbate, 1 : 3-dihydroxypropane disorbate, glycerol trisorbate, sorbates of diethyleneglycol and pentaerythritol and the glyceryl ester of octatrien-(2 : 4 : 6)-oic-(1) acid may be used as a blend or hardener for liquid polystyrene, vinyl chloride-vinyl acetate copolymers and their hydrolysed products, polyvinyl butyral, or alkyd resins.ALSO:A process for preparing esters derived from an aliphatic polyhydric alcohol and an aliphatic unsaturated monobasic carboxylic acid having conjugated double bonds, one of such bonds being in configuration with the carbonyl group of the acid, comprises reacting said alcohol and acid at a refluxing temperature not in excess of 170 DEG  C. in the presence of an acidic esterification catalyst and a water-immiscible organic solvent capable of producing with water, formed in the reaction, an azeotropic mixture vaporizing at a temperature not in excess of 170 DEG  C.  The organic solvent condensed from the azeotropic vapours may be returned to the reaction vessel.  The reaction mixture may contain a polymerization inhibitor.  Polyhydric aliphatic alcohols which may be employed include alkylene glycols and polyglycols, glycerols and polyglycerols, erythritol and pentaerythritol and their polymers, sorbitol, mannitol or trimethylol-propane proportions in excess of stoichiometeric proportions normally being employed. Suitable aliphatic unsaturated monocarboxylic acids comprise those having a straight-chain structure such as sorbic, b -vinylacrylic, octatrien - (2,4,6) - oic, decatetraen-(2,4,6,8)-oic, a -methyl sorbic, a -ethyl sorbic, g -e-dimethyl sorbic, b  g -dimethyl sorbic and 2,6 - dimethyl - decatrien - (2,6,8) - oic - (10) acids and those having cross conjugate chain structures such as a -b -di-isopropylidene-propionic acid.  Suitable organic solvents are benzene, toluene, xylene, hydrogenated petroleum naphtha, methyl isobutyl ketone, o-bromotoluene, di-isobutyl ketone and dichlorethyl ether.  Acidic esterification agents employed may be perchloric, hydrochloric, nitric or sulphuric acids, the latter preferred, or sulphonic acids such as benzene and toluene sulphonic acids, boron trichloride, aluminium chloride, zinc chloride and boron trifluoride. Suitable polymerization inhibitors are sulphur, selenium and hydroquinone. In examples: (1) diethylene glycol is esterified with sorbic acid by heating in the presence of xylene, concentrated sulphuric acid and sulphur under carbon dioxide, water being removed from the distillate and the xylene refluxed; (2) glycol disorbate is prepared from ethylene glycol and sorbic acid by the method of example (1); (3) 1,3-dihydroxypropane disorbate is prepared from 1 : 3-dihydroxypropane and sorbic acid by heating in the presence of xylene, p - toluenesulphonic acid and sulphur; (4) glycerol trisorbate is prepared by heating glycerol and sorbic acid in the presence of water, toluene and sulphuric acid; (5) sorbic acid and pentaerythritol are heated with toluene and sulphur under carbon dioxide and sulphuric acid in methyl alcohol is added; (6) glycerol is esterified with sorbic acid as in (4), but using boron trifluoride as catalyst instead of sulphuric acid; (7) octatrien-(2,4,6)-(1) acid and glycerol are refluxed with sulphuric acid, methanol and toluene.