Vicinal 13C?13C spin–spin coupling constants of 1-butanols. Conformational and substituent effects

A series of (>90% isotopic purity) ¹³C-labeled aliphatic alcohols of the general structure C? C? C? ¹³C? OH were synthesized and studied by ¹³C n.m.r. to obtain all ¹³C? ¹³C couplings involving the labeled carbon. The ²J(CC) values were small (<0.5 Hz) and contrast with the large (up to 2.7 Hz) ²J(CC) values obtained in a previous study for 2-butanols. The ³J(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 ³J(CC) values is small.