Vicinal 13 C 13 C spin–spin coupling constants of 1‐butanols. Conformational and substituent effects

A series of (>90% isotopic purity) 13 C‐labeled aliphatic alcohols of the general structure CCC 13 COH were synthesized and studied by 13 C n.m.r. to obtain all 13 C 13 C couplings involving the labeled carbon. The 2 J (CC) values were small (<0.5 Hz) and contrast with the large (up to 2.7 Hz) 2 J (CC) values obtained in a previous study for 2‐butanols. The 3 J (CC) values, however, were strikingly similar in the two classes of compounds with respect both to magnitude and to conformational dependency. Thus, the effect of the hydroxyl substituent on 3 J (CC) values is small.