THE ACTION OF PYRIDINE ON THE DINITRATE ESTERS OF 1,4;3,6-DIANHYDROHEXITOLS

Abstract

In contrast to the rapid and selective replacement of a secondary O-nitro group by hydrogen in the hexitol hexanitrates at 25–50 °C, the dinitrate esters of the 1,4;3,6-dianhydrides of D-mannitol, D-glucitol, and L-iditol (cis-isohexides) reacted slowly in anhydrous pyridine at 87–115 °C. The chief products were a polymer, nitrogen oxides, and pyridinium nitrate; the yield of mononitrates did not exceed 10% and none of the parent diols were formed.The relative rates of the first-order decomposition of the nitroxy groups in the isomeric dinitrates were in reverse order to that for SN2 reaction at carbon in these compounds. Activation energies and frequency factors were determined and water was shown to have a retarding effect.Thermal decomposition of the dinitrates in solution in nitrobenzene, m-xylene, or sym-tetrachloroethane was much slower than the pyridine reaction at the same temperature and was independent of the polarity of the solvent and the conformation of the ester.