Methylcyclopropane, excited, from

Both T-substituted 1-pentene and 3-methyl-1-butene were observed in yields comparable to the other T-pentene isomers. This observation clearly indicates that the primary source of T-pentene in these systems is through the loss of H atoms from the excited radicals formed by hot tritium addition with opening of the cyclopropane ring. The almost lack of isomerization of the T-substituted parent molecule set an upper limit for the energy left in the T-substituted parent molecule due to the reaction with energetic tritium the upper limit is equal to the activation energy for isomerization (65 kcal mol for cyclopropane and methylcyclopropane and about 62 kcal mol for ethylcyclopropane and dimethyl-cyclopropane. ... 

This consequence is directly verifiable in a variety of experiments. The most significant of these are the chemical activation studies (8-13) reported in the 1960s and 1970s. The principle idea of these studies is to prepare a highly excited molecule by two or more different chemical means and then to compare the rates and branching ratios of unimolecular reactions derived from these different preparations. This is illustrated by a comparison of the unimolecular reactions of methylcyclopropane following preparation from two reactions ... 

Several recent studies suggest that the basic assumption of the RRKM theory of rapid intramolecular vibrational-energy transfer is, in fact, essentially correct. For example, several cases have been well documented where the experimental results are contrary to those predicted from physical assumptions of Slater s theory [14]. Butler and Kistiakowsky [15] studied the isomerization of vibrationally excited methylcyclopropane molecules formed by two different chemical reactions (I). 

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