Temperature dependence of the carbon‐13 chemical shifts of paraffinic hydrocarbons

A study of several linear and branched alkanes indicates that the temperature dependence of 13C chemical shifts is a complex phenomenon in which several non‐additive effects may be operative. The chemical shift temperature coefficients dδ/dT do, however, reveal some systematic trends which could be helpful in the assignments of 13C resonances. An empirical equation is proposed (akin to that of Grant and Paul for 13C chemical shifts) which accurately correlates all the data obtained near ambient temperatures.