Carbon-13 nuclear magnetic resonance spectroscopy: VIII—aliphatic hydrocarbon derivatives

✍ Scribed by Goh Miyajima; Kichisuke Nishimoto

• Publisher: John Wiley and Sons
• Year: 1974
• Tongue: English
• Weight: 666 KB
• Volume: 6
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270060604

✦ Synopsis

Abstract

Carbon‐13 NMR chemical shifts of several series of aliphatic hydrocarbon derivatives–‐substituted methanes, ethanes, isopropanes, n‐propanes and n‐butanes–‐were found to have a linear relationship with σ‐electron densities (Q^σ^) calculated by the method of σ‐included ω‐HMO. A plot of the ^13^C NMR chemical shift of a given carbon in a substituted propane versus that of the corresponding carbon in a substituted butane showed a good linearity with a slope of unity. The values of the ^13^C chemical shifts of the n‐butyl derivatives converged rapidly to a constant value as the distance from the substituent increased. Accordingly, the value for the δ‐carbon was found to be constant regardless of the substituent. These results show that the ^13^C NMR chemical shifts of aliphatic hydrocarbon derivatives are mainly dependent on inductive effects. The convergence shown by the experimental results is supported by the calculated results of the Q^σ^ values of the n‐butyl derivatives.