Über den einfluß des lösungsmittels beim thermischen zerfall des azoisobuttersäuredinitrils

The thermal decomposition of azo-bis-isobutyronitrile in a series of 10 solvents was investigated. The reaction is strictly of first order. The rate is different in all solvents, the maximum difference at 60°C amounts 40% (malonic ester/cyclohexanol), which corresponds to a difference of 250 cal/mole in the free enthalpy of the transition state. The greater differences of the activation enthalpy are compensated by similar differences of the entropy of the transition state.