Nuclear Magnetic resonnce spectroscopical studies of 2-carbonyl derivatives f five-membered monohetetocycles and determination of aromaticity indices.

摘要

~1H And ~13C chemical shifts of formyl,acetyl,benzoyl,and metoxycarbonyl derivatives of benzene,thiophene,pyrrole and furan in chloroform-d,methanol-d_4,and DMSO-d_6 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 withthe reactivities of thecarbonyl groups are discussed.