GB951600A - Improvements in and relating to the manufacture of carbon tetrachloride - Google Patents

Abstract

C Cl4 is made from CS2 by utilising the reactions: (1) 2CS2 +6Cl2 --> 2C Cl4 +2S2Cl2 (2) 2S2Cl2 +CS2 <FORM:0951600/C2/1> C Cl4 + 3S2 wherein a mixture of 10-35% of CS2, 25-45% of CCl4 and 25-45% of S2Cl2 and Cl2 is flowed through one or more chlorination zones at 50-105 DEG C. in which reaction (1) occurs giving a mixture of CCl4 and S2Cl2 containing an amount of 0.03 to 0.1% of CS2 which is continuously distilled to recover CCl4 overheads and still bottoms comprising S2Cl2. This S2 Cl2, preferably mixed with a little Cl2 to form 1-5% of S Cl2, which acts as a catalyst for reaction (2), is treated with a stream of CS2 to form (reaction (2) a mixture of CS2, CCl4, S2Cl2 and S. Other catalysts for this reaction are iron and ferric chloride. The reaction mixture is heated to a temperature above the B.P. of S2Cl2 but below the B.P. of S e.g. 180-275 DEG C., preferably 200 to 240 DEG C., to separate a mixture of CS2, CCl4 and S2 Cl2 from the S, which is recycled to the chlorination stage where fresh CS2 may be added. The S may be stripped with CS2 vapour and the resultant vapours used to provide the CS2 for the reaction with S2Cl2. Preferably the mixture fed to the chlorinator has 10-25% CS2, 35-45% CCl4 and 35-45% S2Cl2. When chlorination is effected in a plurality of zones 80-98% of the CS2 is reacted in the zone or zones preceding the final one. In this embodiment the chlorination gas may be chlorine containing diluents e.g. air, and the degree of chlorination, in any zone, may be controlled optically by a colourimeter. The distillation of the CCl4 from the S2Cl2 is preferably effected so that 3-7% of CCl4 remains in the bottoms. Examples are given and apparatus described (not shown). Specification 874,607 is referred to.