GB618478A - Stabilization of nuclear chlorostyrenes - Google Patents

Abstract

The polymerization of polymerizable nuclear chlorinated (especially dichlorinated) styrenes during distillation is inhibited by conducting the distillation in the presence of an effective amount (i.e. from less than 0.01 per cent upwards, preferably about 0.1 per cent) of a nitrosophenol. When distilling nuclear dichlorinated styrenes from reaction mixtures containing them, using a fractionating column or reflux condenser from which reflux condensate is returned to the distilling zone, it is advantageous to employ 1-nitroso-2-naphthol as inhibitor and to add it, preferably in solution in purified dichlorostyrenes, to the reflux condensate, an example being given of this procedure. p-Nitrosophenol is also particularly effective as an inhibitor, and others specified are nitrosothymols, nitrosocresols, nitrosoresorcinols, nitrosocatechols, nitrosopyrogallols and halogen-substituted nitrosophenols.ALSO:The polymerization of polymerizable nuclear chlorinated (especially dichlorinated) styrenes is inhibited by incorporating therewith an effective amount (i.e. from less than 0.01 per cent upwards, preferably about 0.1 per cent) of a nitrosophenol. In examples: (1) a mixture of crude dichlorostyrenes produced by dehydrochlorination of chloroethyldichlorobenzenes is distilled in the presence of 1-nitroso-2-naphthol; (2) p-nitrosophenol, 5-methyl-3-isopropyl-4-nitrosophenol and 1-nitroso-2-naphthol are added to separate portions of mixed nuclear dichlorostyrenes, and the products are tested for resistance to polymerization in a test tube immersed in boiling water; (3) a mixture of nuclear dichlorostyrenes containing 1-nitroso-2-naphthol is stored at 20 DEG C. Other inhibitors specified are: nitrosocresols, nitrosoresorcinol, nitrosocatechols, nitrosopyrogallols and halogen-substituted nitrosophenols.