Hydrogenolysis of chlorobenzene, dichlorobenzenes and chlorotoluenes by in situ generated and gaseous hydrogen in alkaline media and the presence of Pd/C catalyst.

A method for dechlorination of chloroaromatic compounds at room temperature and atmospheric pressure by an in situ generated--in reaction of Al particles with water--or gaseous hydrogen in alkaline media and the presence of Pd/C catalyst was thoroughly investigated, having in mind its possible application in utilization of organochlorine waste. Conversion degree to dechlorinated compounds depended on the constitution of substrates and ranged between 88% and 96% when in situ hydrogen was used (at substrate (chlorine) to catalyst molar ratio 550:1 and over twofold stoichiometric excess of Al relative to substrate (chlorine); the process lasted ca. 26 h until all Al was consumed), or 90-97% if gaseous hydrogen was purged. Effectiveness of dechlorination was markedly affected by stirring, i.e. size of the stirrer and speed of revolution. Prospects for application of the method described were briefly outlined.