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

Abstract

The gas-phase pyrolysis of bis (2-chloroethyl) sulphide (usually named yperite) has been investigated in a static reactor in the following conditions, temperatures ranging from 300 to 500°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 decomposition of bis (2-chloroethyl) sulphide, we have also studied the pyrolysis of the oxygenated equivalent compound, bis (2-chloroethyl) ether, under the same conditions. A 99% conversion of bis (2-chloroethyl) sulphide was obtained at 500°C; the major products detected were vinyl chloride and ethylene. In the case of bis (2-chloroethyl) ether, the major products observed were vinyl chloride, methyl chloride, methane, ethylene and carbon monoxide. For both compounds studied, a kinetic mechanism has been proposed which involves a molecular four-centre elimination reaction and free-radical reactions. The study clearly shows the possible industrial use of this process to destroy agents in chemical weapons and a first range of temperatures and reaction times has been selected for a future reactor design.