Improved Studies on the Synthesis, Characterization and Crystal Structure of 2,2-Dimethyl-5-nitro-5-nitroso-1,3-dioxane

The synthetic process for 2,2-dimethyl-5-nitro-5-nitroso-1,3-dioxane (DMNNDO) was improved by using tri(hydroxymethyl)nitromethane and acetone as starting materials through a "one-pot" method combined with alkaline hydrolysis and nitrosation reactions. The yield of DMNNDO was increased from 37% to 45%. The structure of DMNNDO was characterized by IR, H-1 NMR, C-13 NMR, and elemental analysis. Also the thermal decomposition of DMNNDO was studied by using DSC and TG-DTG to find that there are primarily two exothermic decomposition processes between 90 and 300 degrees C. The crystal structure of DMNNDO was studied by X-ray single-crystal diffraction for the first time. The molecular structure exists as a dimeric form due to the presence of nitroso group. The crystal belongs to monoclinic system, space group C2/c with a = 14.515(3), b = 9.955(2), c = 11.897(2) angstrom, beta = 98.500(3)degrees, V = 1.6998(2) nm(3), Z = 8, D-c = 1.486 g.cm(-3), mu = 0.128 mm(-1), F(000) = 800, S = 1.055, R = 0.0358 and wR = 0.0917. In particular, DMNNDO could be easily hydrolyzed in hydrous systems and the hydrolysis mechanism in CDCl3 was revealed by means of NMR monitoring.