Patent GB-363099-A (GB)
Title: Improvements in the manufacture of oxidation products of trichlorethylene
IPC: C07C51/58
Filed: 1930-11-20
Abstract: In the oxidation of trichlorethylene by treatment with oxygen, dichloracetyl chloride and trichlorethylene oxide are produced, together with hydrogen chloride, carbon monoxide and phosgene.ALSO:Trichlorethylene is oxidized by means of oxygen yielding dichloracetyl chloride and trichlorethylene oxide (together with hydrogen chloride, carbon monoxide and phosgene, and small amounts of high-boiling substances) and the liquid product, preferably freed by fractional distillation from the high-boiling constituents, is then treated at a raised temperature to convert it into dichloracetyl chloride, or chloral.  If the mixture is maintained at an elevated temperature, e.g. 200 DEG  C., if desired in the presence of active carbon or an organic nitrogen base as catalyst, it is transformed completely into dichloracetyl chloride. If, however, a metallic chloride decomposable by water is used as catalyst, a mixture of chloral and dichloracetyl chloride is obtained.  The acid chloride may be converted into derivatives such as dichloracetic acid and its amide.  In the examples, (1) trichlorethylene, previously purified by careful fractionation, is treated in the hot with oxygen, and the oxidation product is freed from substances boiling above 107 DEG  C. by fractionation.  The purified oxidation product is treated in the cold or hot with 0,1 per cent of an organic base, e.g. dimethylamine, trimethylamine, diethylamine, triethylamine, dibutylamine, tributylamine, mono- and dimethyl aniline, pyridine, piperidine, quinoline, or pyrrole; and the conversion to dichloracetyl chloride occurs with strong evolution of heat.  To control the heat evolution, the catalyst may be mixed with dichloracetyl chloride, into which the oxidation product is allowed to flow with stirring and cooling, and the temperature is allowed to rise to about the boiling-point, if necessary with the addition of a further trace of catalyst.  The dichloracetyl chloride is freed from unchanged trichlorethylene by fractionation.  (2) In the process of example (1), the organic amine is substituted by antimony tri- or pentachloride, titanium tetrachloride, aluminium chloride, or ferric chloride.  After fractionation from unchanged trichlorethylene, there remains a mixture of about equal parts of chloral and dichloracetyl chloride, which may be separated by fractionation.  Chloral may also be isolated by converting the acid chloride to dichloracetic acid, and separating the two substances by fractionation; alternatively, the mixture is allowed to stand for some hours, whereupon meta-chloral separates out, and the dichloracetyl chloride is distilled off or dissolved out with an indifferent solvent such as di- or trichlorethylene.  Monomeric chloral is obtained again by distillation.  The Specification as open to inspection under Sect. 91 (3) (a) states that a catalyst which is not also an anti-oxidation catalyst may be added to the trichlorethylene before or during the oxidation.  Thus if antimony trichloride is added to trichlorethylene, and oxygen is passed through at 70 DEG  C., a mixture containing dichloracetyl chloride and chloral is obtained. This subject-matter does not appear in the Specification as accepted.