Application of 15N nuclear magnetic resonance spectroscopy to the determination of the stability of aryl nitrogen mustards.

An excellent correlation has been shown to exist between the 15 N NMR chemical shifts of a series of aryl nitrogen mustards and the Hammett constant σ, which is much improved by the use of σ - . These chemical shifts also correlate well with the hydrolysis rates of the compounds in 50% aqueous acetone at 66°C and their alkylation of 4-(4'-nitrobenzyl)pyridine under similar conditions. Thus 15 N NMR is a straightforward and material-conserving method for estimating the relative stabilities of aryl nitrogen mustards