Prediction of ¹³C nuclear magnetic resonance chemical shifts (∑¹³C_n) in alkanes and cycloalkanes

Abstract

A topological method is described for prediction of ¹³C NMR chemical shifts (∑¹³C_n) of alkanes and cycloalkanes using recently introduced PI (Padmakar-Ivan) index and to establish relative potential of PI index compared to Wiener (W) and Szeged (Sz) indices. Regression analysis or the data shows that in the case of alkanes the PI index gives somewhat better results than W, whereas in the case of cycloalkanes neither PI nor W nor Sz are applicable. However, excellent results are obtained when the cycloalkanes are classified into low, middle, and high ring-size.