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 S_N2 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.