Vinylamines total energies

Newman projections along the N—C1 bond showing the six conformations, 116 to 121, of vinylamine (115) whose total energies in various basis sets have been collected in Table 9. (O denotes C1.) Values for substituted vinyl amines refer to the same type of the five conformations 116, 117 and 119 to 121. 

This quantum chemical calculation was made at the respectable DZP level, where the authors made the generally reasonable assumption that zero-point energy and 0-298 kJ corrections largely cancel in the ca 22 kJ mol -1 total energy difference of vinylamine and its more stable, but likewise unisolated, acetalimine isomer. 

From the total energies presented in Table 9, theoretical gas-phase protonation energies, PE, are derived and presented in Table 15. In accordance with our calculation it has been shown experimentally that, in the gas phase, C protonation occurs with enamines and a large substituent effect due to substitution by an a-methyl group was observed . The intrinsic C-protonation basicity, PE, of vinylamine (115) is calculated to be larger by 18.7 kcal mol than its N-protonation basicity and by 6.8 kcal mol larger than that of ethylamine. The PE of N protonation of 115 is higher than that of... 

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