Nuclear magnetic resonance spectroscopical studies of 2-carbonyl derivatives of five-membered monohetero-cycles and determination of aromaticity indices

초록

1H And 13C chemical shifts of formyl, acetyl, benzoyl, and methoxycarbonyl derivatives of benzene, thiophene, pyrrole and furan in chloroform-d, methanol-d<inf>4</inf>, and DMSO-d<inf>6</inf> are examined. Deviation of the signals of the ring protons and carbonyl carbons provide bases for estimating the indices of aromaticity of the heterocycles. The exceptionally large carbonyl stretching vibration of furan derivatives and correlations of the stretching frequencies with the reactivities of the carbonyl groups are discussed.