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The decomposition of 1,4;3,6-dianhydrohexitol dinitrates

University of British Columbia

The dinitrate esters of the three known isohexides (1,4;3,6-dianhydrohexitols) were prepared and characterised and the rates and products of their reaction with pyridine were investigated. It was shown that none of the parent isohexides were formed in the reaction and the yield of mononitrates did not exceed 8%. These results differed from the rapid and selective removal of one nitrate group and its replacement by a hydroxyl group which occurs when hexitol hexanitrates react with the same reagent. Comparative rates of reaction for the three isohexide dinitrates and activation energies were determined. Addition of water to the pyridine caused a retardation of rate. The rate of thermal decomposition of these nitrate esters in other organic solvents was found to be slow at the temperatures used for the pyridine reaction and independent of the solvent and isomer used. The rates of the reactions of isohexide ditosylates with sodium iodide in acetic anhydride were investigated and used to prove the position of monotosylation of isosorbide. The reaction of iodo derivatives of the isohexides with silver nitrate in acetonitrile gave a low yield of a mixture of the isohexide nitrate products. The rates of these reactions together with those of alkali on the isohexide ditosylates and acetic anhydride/sulphuric acid on the dinitrates were compared to those of the dinitrates with pyridine. Appropriate chromatographic and analytical procedures were developed for the separation and identification of the isohexides and their derivatives.

Text

2012-02-18

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http://hdl.handle.net/2429/40800

Chemistry

University of British Columbia

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