Azobisisobutyronitrile toxicity

Tris[(2-perfluorohexyl)ethyl]tin hydride has three perfluorinated segments with ethylene spacers and it partitions primarily (> 98%) into the fluorous phase in a liquid-liquid extraction. This feature not only facilitates the purification of the product from the tin residue but also recovers toxic tin residue for further reuse. Stoichiometric reductive radical reactions with the fluorous tin hydride 3 have been previously reported and a catalytic procedure is also well established. The reduction of adamantyl bromide in BTF (benzotrifluoride) " using 1.2 equiv of the fluorous tin hydride and a catalytic amount of azobisisobutyronitrile (AIBN) was complete in 3 hr (Scheme 1). After the simple liquid-liquid extraction, adamantane was obtained in 90% yield in the organic layer and the fluorous tin bromide was separated from the fluorous phase. The recovered fluorous tin bromide was reduced and reused to give the same results. Phenylselenides, tertiary nitro compounds, and xanthates were also successfully reduced by the fluorous fin hydride. Standard radical additions and cyclizations can also be conducted as shown by the examples in Scheme 1. Hydrostannation reactions are also possible, and these are useful in the techniques of fluorous phase switching. Carbonylations are also possible. Rate constants for the reaction of the fluorous tin hydride with primary radicals and acyl radicals have been measured it is marginally more reactive than tributlytin hydrides. ... 

Azobisisobutyronitrile is reported useful as a blowing agent for the production of polymer foams and as a polymerization catalyst (Refs 4 7). The tetramethyl-succinonitrile product of its decompn is toxic (Ref 5)... 

To 5 gm vinylferrocene in 5 ml benzene in Fischer-Porter aerosol compatibility tubes equipped with valves is added 2.52 wt% of azobisisobutyronitrile, based on vinylferrocene. Caution benzene is extremely toxic.) The tubes are degassed by three alternate freeze-thaw cycles and then filled with nitrogen to slightly above ambient pressure and placed in a 80°C constant-temperature bath. After 2 hr, another portion (2.48 wt%) of azobisisobutyronitrile is added and the heating continued for a total of 20 hr. The tube is cooled, vented, and the polymer is precipitated in methanol. The polymer is purified by two more precipitations and then dried at 70°-80°C under vacuum to give 3.1 gm (62.4% yield), m.p. 281°-285°C (yellow powder). 

Azobisisobutyronitrile. Azobisisobutyronitrile is now scarcely used and only to foeim PVC and PS. This limitation in its application comes from the high toxicity of the dinitrile of tetramethylsuccinic acid, a major product of its decomposition. 

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