Nuclear magnetic resonance study on the model compounds for poly(N‐alkylglycine)s

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Abstract
Cis‐trans isomerism was investigated with N‐acetyl and N‐propionyl, N‐alkylglycine dimethylamides as model compounds for poly(N‐alkylglycine dimethlamides as model compounds for (N‐alkylglycine)s using n.m.r. spectroscopy. The population of the cis isomer measured in benzene and methylene chloride solutions did not show any marked dependence on the bulkiness of N‐alkyl substituents. This contrasts with polyN‐alkylglycine)s, whose cis isomer population increased with the introduction of bulky N‐alkyl groups. Kinetics of the Cis‐trans isomerization was also investigated with N‐acetyldimethylamides of sacrosine, N‐n‐propylglycine, and N‐isopropylglycine in tetrachloroethane solution. The δG‡ values for Cis‐trans isomerization in these amides were 18 ∼ 19 kcal/mole, which were virtually the same as that of polysacrosine.