Criteria of stability for dinitrogen pentoxide in organic media and anhydrous HNO3. Appraisal of the nitrating efficiency of some nitronium complexes in sulfolane
✍ Scribed by A. Boughriet; M. Wartel
- Publisher
- Elsevier Science
- Year
- 1991
- Tongue
- English
- Weight
- 922 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0013-4686
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✦ Synopsis
Ahatract-The electrochemical behaviour of nitrate ion has been investigated in aprotic media by means of linear and cyclic voltammetry at a platinum electrode. It has been shown that the electro-oxidation of NO, is complicated by the occurrence of the instable species "NO;", leading to the generation of dinitrogen pentoxide according to: 2N0, + 2NO; + 2e-+N,O, + ;O,. In order to assess the reversibility of this couple, we studied the anodic E/i curves obtained with NO; solutions in sulfolane and propylene carbonate. We found a linear E us log{(i)3/2/(iN0, -i)'} plot with a slope slightly higher than the theoretical value expected: 2.303RT/2F', on account of the hydrolysis of N,O, into HNO, occurring partially at the surface of the Pt electrode. We then appraised the ionic dissociation of N,O, in sulfolane as: N,O, + NO: + NO;. For this reaction diagnostic criteria characterizing the degree of stability of N,O, have been deduced. The equilibrium constants corresponding to the molecular decomposition of N,O, alone and in the presence of NO have been assessed in sulfolane. We have extended this work to the study of the nitrating characteristics of various nitronium complexes, NO,. Bs (where Bs is an inorganic base). We have also undertaken the electrochemical and Raman spectroscopic study of N,O, generated in pure nitric acid through the electrooxidation of NO,, N,O, or HNO,. From these results, we have attempted to explain the behaviour of N,O, and its relative stability in pure nitric acid.