GB805817A - Process for purifying trichloro-and tetrachlorobutane - Google Patents

Abstract

1:2:3 - Trichloro- and 2:2:3:3 - tetrachlorobutane are recovered from mixtures thereof by contacting such mixtures under adduct forming conditions (in the presence of methanol with or without a non-complexforming solvent) with at least sufficient thiourea (3 mols. per mol. of halohydrocarbon) to convert substantially all the tetrachlorobutane into its adduct, filtering, and recovering substantially pure trichlorobutane from the filtrate by washing with water or distillation. Alternatively, a large excess of thiourea under the same conditions yields a mixture of both adducts, which is treated with water at a low temperature to liberate the trichlorobutane. The more stable tetrachlorobutane adduct is filtered off and decomposed by steam distillation when the tetrachlorobutane crystallizes in the distillate and is filtered off, a small quantity of trichlorobutane being recovered from the mother liquors. In an example, the separation of a mixture of 1:2:3-trichlorobutane and 2:2:3:3 - tetrachlorobutane using approximately 5 mols. of thiourea per mol. of tetrachlorobutane is described. Specification 805,816 is referred to.