Nitramide , decomposition reactions

In contrast to the decomposition of nitramide, these reactions are catalysed by acids and not by bases. The general mechanism may be written as follows ... 

Thermal decomposition of nitramide, H2NNO2, or hyponitrous acid H2N2O2 (both of which have the empirical formula N2O.H2O) have also been used. The mechanisms of these and other reactions involving simple inorganic compounds of N have been reviewed. 

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... 

Laboratory syntheses of nitrous oxide include the decomposition of hyponitrous acid (236) or nitramide (314), the reaction of nitrous acid with hydroxylamine (146) or hydrazoic acid, (147) and the reaction of amidosulfonic acid with concentrated nitric acid (148) ... 

Since 1924, the Bronsted relation has been applied to many general acid and base catalysed reactions, such as those discussed in Sect. 2.2, as well as to proton transfer equilibria like (43)—(45). Over limited ranges of acid strength and for variation within a similar catalyst type, G and a or j3 are constant and the relation holds well. Different catalyst types in a reaction often do not fit on a single Bronsted plot, but give different Bronsted lines. This was observed for the decomposition of nitramide [68]. It has also been observed in proton transfer from l,4-dicyano-2-butene(51)... 

Where the second term in equation (4) is negligible but the water reaction is sufficiently large to be detected, the result is curve d. The important example is the decomposition of nitramide (Brpnsted and Pedersen, 23), and others are the hydrolysis of jS-lactones (Johansson, 29) and the halogenation of nitroparaffins (Pedersen, 30). 

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... 

Bransted LFER. Bronsted and Pederson (1923) were the first to describe a relationship between rates and equilibria for a series of compounds. They found that log/cB for base-catalyzed decomposition of nitramide, H2N202, varies linearly with log/CHB+, the acidity constant of the conjugate acid of the catalyst. Rate constants for many other acid- or base-catalyzed reactions (including the hydrolysis of amides, esters, carbamates, and organophosphates, and dissociation of acids and metal-ion complexes) are log-log related to the acid (or base) dissociation constant of the catalyst and follow either of the equations... 

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 ... 

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. 

The reaction of acid with potassium nitrocarbamate results in the formation of nitramide (equation 15.107) which is an isomer of hyponitrous acid. Nitramide has been structurally characterized one N atom is trigonal planar (O2AN) and the other is trigonal pyramidal (H2AN)- The compound is potentially explosive, and undergoes base-catalysed decomposition to N2O and H2O. 

The ionization and enolization of carbonyl compounds This class of reaction has been widely quoted in the last chapter as an example of proton transfer leading to subsequent chemical change, and of prototropic isomerization. It was also used to illustrate the problems involved in deciding for or against a ternary catalytic mechanism in aqueous solution. Like the decomposition of nitramide, it occupies an... 

It can be seen from Figures 8 and 9 that a kinetic investigation over a limited range of ApX would yield a linear relation between Igk and ApK, but with a slope less than unity. This type of relation has been known for many years for catalysed reactions in the form of the Bronsted relation, first proposed by Bronsted and Pedersen in 1924 on the basis of their experimental w ork on the decomposition of nitramide. It relates the effectiveness of a catalyst to its acid-base strength, having the form... 

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