Accelerated decomposition of α.α′ ‐ azo‐bis‐isobutyronitrile by organoaluminum compounds

An enhanced radical decomposition rate of α.α′ ‐ azo‐bis‐isobutyronitrile (AIBN) was observed when AIBN was coupled with AlEt 3 . Ethyl radical formation was also observed in the AIBN/AlEt 3 system. The nitrile stretching band in the spectrum of AIBN/AlEt 3 was shifted to a higher wave number as a result of a complex formation. Isobutyronitrile radicals as well as ethyl radicals were detected in this system by measurements; the hyperfine coupling constants coincide well with those predicted with the HÜCKEL LCAO‐MO calculation. The binary systems, AlBN/AlEt 3 and AIBN/AlEt 2 Cl are excellent radical initiators for the polymerization of vinyl chloride and styrene. Neither ZnEt 2 nor BEt 3 exhibited such an effect upon the decomposition of AIBN.