Thermal decomposition of bis (2-chloroethyl) sulphide and bis (2-chloroethyl) ether between 300 and 500 degrees C

The gas-phase pyrolysis of bis (2-chloroethyl) sulphide (usually named yper ite) has been investigated in a static reactor in the following conditions, temperatures ranging from 300 to 500 degrees C, an initial pressure of 16. 67 kPa with a dilution in nitrogen and reaction times ranging from 1 to 10 min. To obtain a better understanding of the mechanism of the thermal decom position of bis (2-chloroethyl) sulphide, we have also studied the pyrolysi s of the oxygenated equivalent compound, bis (2-chloroethyl) ether, under t he same conditions. A 99% conversion of bis (2-chloroethyl) sulphide was ob tained at 500 degrees C; the major products detected were vinyl chloride an d ethylene. In the case of bis (2-chloroethyl) ether, the major products ob served were vinyl chloride, methyl chloride, methane, ethylene and carbon m onoxide. For both compounds studied, a kinetic mechanism has been proposed which involves a molecular four-centre elimination reaction and free-radica l reactions. The study clearly shows the possible industrial use of this pr ocess to destroy agents in chemical weapons and a first range of temperatur es and reaction times has been selected for a future reactor design. (C) 20 00 Elsevier Science B.V. All rights reserved.