Thermal behaviour of organochlorine pesticides in the presence of alkaline substances

Selected organochlorine pesticides, namely lindane, PCNB,p,p′-DDT andp,p′-methoxychlor, and some related compounds (p,p′-DDE andp,p′-DMDE) were heated in the presence of powdered KOH, Na₂CO₃, CaO and CaCO₃ in order to check whether degradation of the compounds is feasible in moderate conditions and temperatures. Thermal analyses, as well as investigations concerning the search for the reaction products revealed that processes occurring at atmospheric pressure are either simple volatilization of organic molecules, observed upon heating of mixtures containing lindane, PCNB,p,p′-DDE andp,p′-DMDE, or volatilization accompanied with decomposition towards HCl andp,p′-DDE andp,p′-DMDE, noted when heating mixtures ofp,p′-DDT andp,p′-methoxychlor with alkaline substances, respectively. Complementary theoretical calculations enabled insight into the mechanism of HCl elimination fromp,p′-DDT andp,p′-methoxychlor.