Patent GB-854239-A (GB)
Title: Process for purifying sorbic acid
IPC: C07C51/46
Filed: 1956-11-19
Abstract: Sorbic acid is purified by co-distilling the impure acid with at least one organic substance other than a polyhydric alcohol or a partial etherification product thereof, inert with respect to sorbic acid, and boiling without decomposition under normal pressure at a temperature in the range 180-300 DEG C.  The organic substance may be a hydrocarbon, e.g. a petroleum portion, dodecane, tetradecane, 5-methyldodecane, dodecene, dicyclohexyl, dicyclohexyl methane, diphenyl, p-ditertiary butyl benzene, tetrahydronaphthalene, 1-and 2-methyl naphthalene, 1-ethyl naphthalene, or naphthalene, a halogenated hydrocarbon, e.g. dichlorododecane, 1,5-dibromopentane, benzotrichloride, ortho- or meta-dibromobenzene, a nitro compound, e.g. nitro-benzene or 2-nitro-toluene, a nitrile, e.g. benzyl cyanide; a carbonyl compound, e.g. acetophenone, dihydrocarvone, or 2-acetyl thiophene; a heterocyclic compound, e.g. chromane or thiophene, an ether, e.g. resorcinol dimethyl ether, diphenyl ether, safrol, or isosafrol; a carboxylic acid, e.g. oenanthic acid, a -ethyl caproic acid, caprylic acid or capric acid; or an ester, e.g. the diethyl ester of succinic or glutaric acid, ethyl benzoate, or the methyl ester of phenyl acetic or salicylic acid.  The organic substance used may be a solid at room temperature but is preferably a liquid boiling at a temperature about 40 DEG C. lower or higher than the boiling point of sorbic acid.  The distillation may be carried out under normal, reduced or increased pressure and is preferably effected under reduced pressure at a temperature below 180 DEG C., e.g. between 118 DEG C. and 180 DEG C.  It is preferred to use about 1 to 15 parts by weight of the organic substance per part by weight of sorbic acid.ALSO:Sorbic acid is purified by co-distilling the impure acid with at least one organic substance (other than a polyhydric alcohol or a partial etherification product thereof) inert with respect to sorbic acid, and boiling without decomposition under normal pressure at a temperature in the range 180 DEG -300 DEG C. The organic substance may be a hydrocarbon, e.g. a petroleum fraction, dodecane, tetradecane, 5-methyldodecane, dodecene, dicyclohexyl, dicyclohexyl methane, diphenyl, p-di-tertiary butyl benzene, tetrahydronaphthalene, 1- and 2-methylnaphthalene, 1-ethylnaphthalene, or naphthalene; a halogenated hydrocarbon, e.g. dichlorododecane, 1,5-dibromopentane, benzotrichloride, ortho- or meta-dibromobenzene; a nitro compound, e.g. nitro-benzene or 2-nitro-toluene; a nitrile, e.g. benzyl cyanide; a carbonyl compound, e.g. acetophenone, dihydrocarvone, or 2-acetyl thiophene; a heterocyclic compound, e.g. chromane or thiophthene; an ether, e.g. resorcinol dimethyl ether, diphenyl ether, safrol, or isosafrol; a carboxylic acid, e.g. oenanthic acid, a -ethyl caproic acid, caprylic acid or capric acid; or an ester, e.g. the diethyl ester of succinic or glutaric acid, ethyl benzoate, or the methyl ester of phenyl acetic or salicylic acid. The organic substance may be a solid at room temperature but is preferably a liquid boiling at a temperature about 40 DEG C. lower or higher than the boiling point of sorbic acid.  The distillation may be carried out under normal, reduced or increased pressure and is preferably effected under reduced pressure at a temperature below 180 DEG C., e.g. between 110 DEG C. and 180 DEG C.  It is preferred to use about 1 to 15 parts by weight of the organic substance per part by weight of sorbic acid.