CHROMATOGRAPHIC AND IR CHARACTERISTICS OF METHYL-SUBSTITUTED, FORMYL-SUBSTITUTED, AND ACETYL-SUBSTITUTED FURANS AND THIOPHENES

The GC and FTIR spectral characteristics of methyl-, formyl-, and acetyl-substituted furans and thiophenes were determined. The substituent contributions to the retention indices were calculated. It was found that contributions of identical substituents differ according to the nature of the heterocycle, their position relative to the heteroatom and other neighboring groups. The contributions of CH3-, CHO-, and COCH3-groups in the beta-position of the cycle for monosubstituted substances were equal to the contributions of these groups in monosubstituted benzenes. The contributions of carbonyl groups in the alpha-position were greater than in the beta-position for the same groups. The contributions were found to be nonadditive for disubstituted methyl and carbonyl-containing thiophenes and furans, The presence of two carbonyl groups as substituents in furans and thiophenes results in reduction of the sorption energy of the latter, which is known as <<negative>> alpha-effect. The scheme for a priori calculation of retention indices taking into account the non-uniformity of the contributions of methyl and carbonyl substituents in thiophenes and furans was suggested. The indices of 12 unknown substances of these classes were calculated.