Nitramides, decomposition

Quantitative study of nucleophilicity can be said to have begun with the work in 1924 of Brpnsted and Pederson (16), who noted a correlation of rates of nitramide decomposition by bases (B ) and strength (pKHB) of the basic catalysts ... 

Figure 7-3. Br nsted plot for the decomposition of nitramide catalyzed by substituted anilines.

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. 

Following three phase transformations [951] (>298 K), NH C decomposition begins [915] in the solid phase at 423 K but only becomes extensive well above the melting point ( 440 K). Decomposition with the evolution of N20 and H20 from the melt is first order [952,953] (E = 153—163 kJ mole-1), the mechanism suggested involving intermediate nitramide formation. Other proposed schemes have identified NOj [954] or the radical NH2NO [955] (<473 K) as possible participants. Studies [956,957] have been made of the influence of additives on NH C decomposition. 

A drop of cone, alkali solution added to solid nitramide causes a flame and explosive decomposition. 

According to Guiochon [17] the experiments with labelled nitrogen atoms seem to support an earlier suggestion of Davis and Abrams [21] that the decomposition of ammonium nitrate may pass through the intermediate formation of nitramide through dehydration of ammonium nitrate in the first stage (7) ... 

Consider the following mechanism for the decomposition of nitramide (NH2N02) in aqueous solution ... 

Example the acid- and base-catalysed decomposition of nitramide... 

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... 

Scheme 1.4 Decomposition of nitramide (3) in aqueous solution via its ac/-form (4) B, catalysed by bases A, catalysed by acids [9, 10].

Correspondingly, in the acid-catalysed decomposition of nitramide (Scheme 1.4A), protonation of 4 on the hydroxyl also leads to an ion (6) which spontaneously fragments, i.e. 6 does not correspond to an energy minimum, so the upper stepwise path in Scheme 1.4A is not viable. The acid-catalysed decomposition of 3 via 4, therefore, also involves concerted proton transfer and fragmentation (the lower path in Scheme 1.4A). 

For the spontaneous decomposition of nitramide (NH2N02) the transition state is assumed to have formula 8, on the supposition that the rate-limiting step is base-catalysed removal of a proton from the (less stable) aci-tautomer (NH N02H). This suggestion is made in the... 

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