REACTIVITY OF NUCLEOPHILIC NITROGEN-COMPOUNDS TOWARDS THE NITROSO GROUP

We discuss the reactivity of 43 nucleophilic nitrogen compounds towards the nitroso group of N-methyl-N-nitrosotoluene-p-sulfonamide (MNTS), and in some cases with alkyl nitrites. The series of nucleophiles considered is structurally very varied, includes members exhibiting the alpha effect, and covers 8 pK(a) units and a range of reactivities of almost five orders of magnitude. The values of solvent isotope effects and activation parameters have been measured and throw light on the structure of the transition states involved. Reactivities do not correlate well with the basicity of the nucleophile, largely owing to the behaviour of primary amines, ammonia and nucleophiles with an alpha effect. Application of the curve crossing model suggests a relationship with vertical ionization potentials. The relationship with Ritchie's N+ scale is discussed, and interesting correlations with the reactivities of the same nucleophiles in various other chemical processes are noted.