A new approach to 13C chemical shift additivity parameters

Abstract

Empirical ¹³C chemical shift additivity parameters having some theoretical significance are derived. The parameters are of two types: the first categorises the type of the carbon and the second takes the proton interactions into consideration and is formulated in terms of the number of protons in α-, β-, γ-, and δ-positions relative to the carbon under study. With eight parameters the difference between calculated and observed chemical shifts lies within the range obtained by older sets of parameters. It is hoped that this approach will aid better understanding of the factors determining ¹³C chemical shifts.