GB602597A - Improvements in the manufacture of para-nitrobenzene sulfonyl chloride - Google Patents

Abstract

p-Nitrobenzenesulphonyl chloride is obtained directly from di-p-nitrophenyldisulphide by treatment with chlorine in presence of nitric and hydrochloric acids (preferably concentrated) and a liquid aromatic compound, substantially inert and immiscible with the acid mixture in amount sufficient to dissolve all the product obtained, hydrocarbons such as benzene, toluene or xylene being preferred. The product is recovered (a) by separating the non-aqueous phase of the reaction-mixture and diluting with a liquid paraffinic hydrocarbon, especially a petroleum fraction of boiling-range 40 DEG C. to 210 DEG C., to effect precipitation; (b) concentrating the non-aqueous phase, prior to diluting with the paraffinic hydrocarbon and purifying the product by extraction with a paraffinic hydrocarbon in a solvent extraction apparatus at a temperature sufficient to maintain the p-nitrobenzene sulphonyl chloride molten; (c) evaporating to dryness the non-aqueous phase, and purifying the crude residue by recrystallization or continuous extraction. Substituted aromatic hydrocarbons, e.g. mono-or di-chlorobenzenes or nitrobenzene may be used, and specified paraffinic hydrocarbons are Skellysolve B, ligroin, petroleum ether, Solvasol and Stoddard solvent. Preferred proportions of the acid components employed are at least 1 mol. of nitric, and 5 mols. of hydrochloric acid per mol. of di-p-nitrophenyl disulphide; and reaction is effected preferably within the range of 25 DEG C. to 100 DEG C. Three examples of the process are included with full experimental details. Di-p-nitrophenyl disulphide is obtained by boiling p-nitro-chlorobenzene with sodium sulphide and sulphur in aqueous alcohol.