Thermodynamic estimation of vapor pressures for carbamate pesticides

Vapor pressures of carbamate and thiocarbamate pesticides were estimated fr om their chemical structures by using the newly developed thermodynamic equ ations. The equations were derived from the modified Watson method by optim izing a parameter and introducing the concept of a number of possible hydro gen-bonding sites for better estimation of vapor pressures. This method cou ld successfully estimate the vapor pressures of the tested pesticides and c orrectly predict vapor pressures, ranging from 10(-5) to 10(1) Pa at 298 K, of other pesticides not being utilized in the optimization procedure.