Nitrogen-14 nuclear magnetic resonance. Part II. Additivity rules for chemical shifts in nitroalkanes

Abstract

Simple empirical rules for ¹⁴N chemical shifts in the systems R¹R²R³C·NO₂ are found. The contributions to the shift from CH₃, RCH₂, and Cl are additive; a small modification is required when further nitro-groups are introduced. In most cases, the agreement between the calculated and observed values is within 1 p.p.m. or about 1–2% of the 70 p.p.m. range of ¹⁴N chemical shifts observed for nitroalkanes.