Contributionof thermal analysis to the description of transport phenomena of pesticides

The vaporization enthalpies of two acetanilide pesticides, alachlor (2’,6’-diethyl-N-(methoxymethyl)-2-chloroacetanilide) and metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-[(1S)-2-methoxy-1-methylethyl] acetamide), were determined by processing non-isothermal thermogravimetry data according to the Clausius-Clapeyron equation. The reliability of the procedure proposed was tested carrying out some experiments at different heating rates using acetanilide as a reference compound. A good agreement is found among the vaporization enthalpies derived from all the multi-heating rate experiments as well as with the one predicted from the vapor pressure data taken from literature. The vaporization temperatures (T _vap=470±2 K and T _vap=479±2 K) and enthalpies (Δ_vap H°(436 K)=85±1 kJ mol^–1 and Δ_vap H°(436 K)=70±1 kJ mol^–1) for alachlor and metolachlor, were selected, respectively.