Theoretical study on the mechanisms of the decomposition of nitrate esters and the stabilization of aromatic amines.

Abstract

The nitrate esters are important components of double-base propellants. Aromatic amines are recommended as the stabilizers to delay the decomposition of nitrate esters and increase their storage time. The decomposition mechanisms of alkyl, alkoxy dinitrate, and poly-fluoride nitrate esters and the stabilizing effect of aromatic amines including new designed phenols are studied at the level of B3LYP/6-31G**. Alkyl and alkoxyl dinitrate esters are likely to be transformed by hydrogen abstraction, which is consistent with that of mononitrate and trinitrate esters. However, for poly-fluoride nitrate esters, NO2 catalyzed self-decomposition is preferred. In addition, comparing with mononitrate and trinitrate esters, the order of their stability is mononitrates > dinitrates > trinitrates. Poly-fluoride nitrate esters have a poorer stability than non-fluorinated nitrate esters. Comparing with parent nitrate esters, the stability of new designed poly-fluoride oxygen-containing nitrate esters is slightly improved. Aromatic amines including new designed phenols are effective stabilizers of nitrate esters, especially when introduced hydroxyl in the para position, can enhance the effects of stabilizers. The rate constants for the decomposition of nitrate esters and the bimolecular reaction between stabilizers and NO2 are calculated by using traditional transition state theory. Graphical abstractComparison between the reaction energy barrier of nitrate esters and stabilizers with NO2.