C-13 NUCLEAR MAGNETIC-RESONANCE SPECTRA OF PARA-AMINOBENZOIC ACID OLIGOMERS - RANGE DEPENDENCE OF ADDITIVE SUBSTITUENT EFFECTS

Analysis of 13C chemical shifts of p-aminobenzoic acid oligomers indicates that 13C NMR additivity rules of 1,4-phenylene derivatives are distorted by interaction among substituents. These interactions are sharply attenuated, and additivity rules become more exact, as the substituents are placed farther apart. Additivity deviation terms of amino-substituted monomeric and dimeric series are correlated with corresponding terms of analogous nitro-substituted series. © 1979.