Evidence for α‐elimination from neopentyl chloride in the gas phase

Experimental evidence is presented for a unimolecular gas‐phase Wagner‐Meerwein shift in neopentyl chloride pyrolysis. In the decomposition of α,α‐neopentyl chloride‐d2 at 445°C, maximally inhibited by cyclohexene, the initial products were isotopically pure 2‐methyl‐1‐butene‐d2 and 2‐methyl‐2‐butene‐d1. Rearrangement, accompanied by loss of either α‐ or γ‐hydrogen in the formation of hydrogen chloride, is consistent with an incipient ion‐pair type of transition state. The cyclohexene maximally inhibited pyrolysis of neopentyl chloride was also examined over the temperature range 424–478°C and Arrhenius parameters of E, 258.7 kJ/mole and logA/sec−1, 13.78, were determined.