The telomerization reaction between acrylonitrile (AN) and trichloroacetyl chloride (TCAC), which is one of the important intermediate steps in the manufacture of a commercial pesticide compound, often results in high temperature and pressure excursions if proper controls are not applied. Hence there is a need for upgrading the process safety of this reaction. Ionic liquid solvents, by virtue of their relatively low volatility and high thermal stability in some cases, have been investigated in this study as a means of improving intrinsic process saftey. Adiabatic calorimetry is a useful analytical technique to monitor the temperature and presssure excursions in reactions, and this technique is applied here for the first time to the telomerization reaction.