Structure of Secondary 2-Azidoethanamines: A Hypergolic Fuel vs. a Nonhypergolic Fuel

摘要

In an attempt to find structural features of 2-azidoethanamines that correlate with their hypergolic ignition delays, density functional theory (DFT) -based quantum mechanics calculations were performed to characterize equilibrium configurations of two secondary 2-azidoethanamines: 2-azido-N- cyclopropylethanamine (CPAZ) and 2-azido-N-methylethanamine (MMAZ). The former is hypergolic with inhibited red fuming nitric acid, while the latter is not. Geometries and normal modes for 23 MMAZ conformers and 42 CPAZ conformers are presented, compared to each other, and compared to geometries and normal modes obtained previously for the hypergolic, tertiary 2-azidoethanamine 2-azido-N ,N- dimethylethanamine (DMAZ). The geometries of greater than N-CH(sub 2)-CH(sub 2)- N(sub 3) chains in analogous MMAZ and CPAZ conformers are found to be nearly identical, and the relative energies of MMAZ conformers as a function of this chain orientation are mimicked in the CPAZ conformers. Some minor differences between the secondary 2-azidoethanamines and DMAZ are noted, but no structural feature is found to be unique to the hypergolic compounds.