Reduction of Mechanical Sensitivity in Alkyl Nitrate Explosives through Efficient Crystal Packing

We report the nitration of tris(hydroxymethyl)aminomethane to tris(nitromethyl)-aminomethane ( 2 ) and its corresponding hydrogen chloride ( 3 ) and hydrogen bromide ( 4 ) salts. While both 3 and 4 conglomerate into tetramers, there are significant differences in the packing of those tetrameric units. In both 3 and 4 the tetrameric units arrange in a hexagonal pattern, but in 3 the units adopt alternating orientations leading to severe interlocking of the alkyl nitrate groups. This ultimately leads to a 2-fold decrease in the mechanical sensitivity of 4 relative to 3 and suggests that utilizing anion size may lead to more efficient packing arrangements and reduced mechanical sensitivity in energetic salts.