Carbon-13 Nuclear Magnetic Resonance Spectroscopy. VII. Studies on Carbon-13 Nuclear Magnetic Resonance Spectra in Aromatic and Heteroaromatic Systems. (3). Carbon-13 Chemical Shifts of Disubstited Benzene Derivatives

Abstract

The ring C-13 nuclear magnetic resonance chemical shifts of 1, 4-and 1, 3-disubstituted benzene derivatives were compared with those of monosubstituted benzene derivatives and the substituent constants σ_i. The slopes of C-1 and C-2 chemical shifts of 1, 4-disubstituted benzene derivatives and also those of C-1 and C-5 of 1, 3-disubstituted series are linear with respect to σ_i. The slopes of other positions have the same characters with those of the corresponding shifts of monosubstituted benzene derivatives.