Homogeneous Catalysis of Gas-Phase Eliminations

No examples of catalysis of unimolecular elimination from halides or esters have been reported. Failes and Stimson (1962) have shown that t-butyl chloride undergoes elimination in the gas-phase at a rate independent of the partial pressure of added sulphur hexafluoride, a substance known to accelerate certain decompositions (Bose and Hinshelwood, 1959). However, the pyrolysis of alcohols, first studied by Kistiakowsky and Schultz (1934) is accelerated by the presence of hydrogen halides (Maccoll and Stimson, 1960). The former authors showed that t-butyl alcohol decomposed homogeneously to yield isobutene and water, at a rate given by 

For the same reaction, Barnard (1959) obtained the rate equation = 3 24x 10 exp( —54,500/JST)sec and further showed that nitric oxide had no effect on the rate. In 

Stimson and co-workers have made a detailed study of the homogeneous catalysis of olefin elimination from alcohols and the results are shown in Table 14. No induction periods were observed and cyclohexene and 

Molecule Catalyst 10-12 A (cm molfl-i sec-i) E (kcal mole i) Temp, range rc) Ref. 

In Table 16, (Stimaon, private communication) the effects of a- and ]8-methyl substitution are shown. 

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