Solvent effects of pyridine on the NMR spectra of carboxylic acids. I—study of the acrylic,trans-crotonic and 3-butenoic acids

Proton magnetic resonance spectral parameters of acrylic, trans-crotonic and 3-butenoic acids, their methyl esters and the corresponding alcohols (COOH substituted by CH₂OH) have been measured for 5% (w/v) solutions in carbon tetrachloride and in pyridine-d₅ at 33·5 °C. The total solvent effect of pyridine on the shifts of the skeleton protons of the acid was found to consist of three different effects independently measured from the reference samples.