Abstract
IN studying the nitration of maize and potato starch, we observed that : (a) a mixture of nitric and sulphuric acids, containing a high proportion of pseudo-nitric acid, namely, an equimolecular mixture of water, nitric and sulphuric acid1, leads to the formation of nitric esters of low nitrogen content (7.1 per cent) ; (b) in the nitration of starch by means of such mixed acids containing decreasing quantities of water and increasing amounts of free sulphur tri-oxide, the degree of nitration of starch is controlled by the proportion of water and sulphur trioxide, respectively, in the nitrating mixture. Nitrates of starch, containing about 13 per cent of nitrogen, could be obtained easily when mixtures of pure nitric acid and oleum2 (2–3 per cent sulphur trioxide) were used. A similar observation has been reported by Fabel3 in the case of the nitration of cellulose. Caesar et al.4 have also found that starches, cellulose and disaccharides are completely and rapidly nitrated by nitrogen pentoxide and that the nitrates thus produced have an unusually high nitrogen content (about 13.9 per cent).
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References
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Nitrogen pentoxide in its free, undissolved state, is not nitronium nitrate, as can be concluded from the observation reported by Hantzsch (Ber., 58, 941 ; 1925).
Chedin, C.R. Acad. Sci., Paris, 201, 552 (1935).
Chedin and Pradier, C.R. Acad. Sci., Paris, 203, 322 (1936)
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ISRAELASHVILI, S. Mechanism of the Nitration of Starch. Nature 165, 686 (1950). https://doi.org/10.1038/165686a0
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DOI: https://doi.org/10.1038/165686a0
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