Spectra nitric esters

Hantzsch opposed the theory of N205 existing in the nitrating mixture HN03 + + H2S04 Due to the importance of the Hantzsch theory in the development of our views on the nature of the nitration process, we shall discuss it in detail. In a number of works Hantzsch [21-23] developed a theory based on Schafer s experiments [24] on the absorption spectrum in ultra-violet light. Schafer s chief observation was, that the spectrum of anhydrous nitric acid in a non-aqueous solvent (hexane, sulphuric acid, etc.) is analogous with the spectra of nitric acid esters,... 

Figure 6. IR spectrum of the styrene-maleic acid ester exposed to nitric acid.

Solutions, of nitric acid have three different ultraviolet-absorption spectra. In dilute aqueous solution, its spfectnim is that of the nitrate ion, NOa . In an inert weakly polar solvent such as chloroform, its spectrum is the same as that of ethyl nitrate, indicating that the nitric acid exists as unionized HNO3. A third spectrum is characteristic of sulfuric acid solutions of nitric acid and its esters, indicating that here nitric acid does not exist as the nitrate ion or as unionized nitric acid. The Haman spec-... 

The H-NMR spectrum of the tetramethyl ester (4b) formed from streptonigrinic acid showed the presence of a primary amino group (2H, 7.84 5, exchangeable with D2O) and treatment of (4b) with nitric acid gave the desaminotetraacid (5) after ester hydrolysis. Thermal decarboxylation of (5) over soda lime produced 5-methyl-2,2 -bipyridyl (6) identical with an authentic sample. 

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