Catalysis nitramide , base decomposition

The base-catalysed decomposition of nitramide (3 in Scheme 1.4) is of special historical importance as it was the reaction used to establish the Bronsted catalysis law. The reaction has been studied over manyyears and considerable evidence indicates that the decomposition... 

Fia. XVI. 1. Bronsted plot for the base-catalyzed decomposition of nitramide. (Data from compilation by R. P. Bell, Acid-Base Catalysis, Oxford University Press, New York, 1941.) + Doubly charged bases, B++, mostly aquo-iona, [M(H20) (0I1)]++. o Doubly charged bases, B". o- Uncharged bases, B° all substituted anilines. 

The term nucleophilicity refers to the relative rate of reaction of an electron donor with a given electrophile, as distinct from basicity, which refers to its relative affinity for a proton in an acid-base equilibrium. A quantitative relationship between rate and equilibrium constants was discovered by Brpnsted and Pedersen (1) in 1924. These authors found that the rate constants for the catalytic decomposition of nitramide by a family of bases, such as carboxylate ions (GCH2C02 ), could be linearly correlated with the acidities of their conjugate acids, pKHB. This observation led to the discovery of general base catalysis and the first linear free-energy relationship, which later became known as the Brpnsted equation ... 

Gi increases with increasing positive charge, and a recent detailed analysis of catalytic effects of uncharged bases in the decomposition of nitramide shows that there is a dependence on the structure of the base (Bell and Wilson, 40 Bell, 41). For the mutarotation of glucose at 18°, Ga = 33 X 10 and y = 0.40. For the more accurate results on the acid catalysis of the acetone-iodine reaction at 25°, Gi and x are 120 X lO" and 0.62, respectively, in the equation... 

The position is similar in basic catalysis. The hydroxyl ion has no strong claims to uniqueness, being merely the anion of a weak acid. According to the Bronsted-Lowry acid-base definition, a base is any species which has a tendency to accept a proton. This obviously includes anions like OH-, CH3COO, HPCL , as well as uncharged basic molecules like ammonia and the amines. Catalysis by all these species was first found in the decomposition of nitramide (Bronsted and Pedersen, 15), and subsequently in many other reactions. 

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