Key Laboratory of Soft Chemistry and Functional Materials of MOE, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China.
Xi'an Modern Chemistry Research Institute, Xi'an 710065, PR China.
J Hazard Mater. 2017 Oct 5;339:401-408. doi: 10.1016/j.jhazmat.2017.06.025. Epub 2017 Jun 16.
The propellants of nitrate esters can be stabilized by some aromatic amines practically. To probe the mechanism of this phenomenon, we performed DFT calculations on: (1) The decompositions of nitrate esters (with and without the catalysis of NO) and (2) the reaction between the stabilizers and the nitro dioxide (NO is released during the storage of nitrate esters). The structures on the reaction paths (reactants, intermediates and products) were optimized at the (U)B3LYP/6-31G** level. It was shown that NO lowers the activation energy barrier in the decomposition of nitrate ester by 11.82-17.86kJ/mol and efficiently catalyzes the rupture of ONO bond. However, the aromatic amines, typical stabilizers for nitrate esters, can easily eliminate NO with activation barriers as low as 27-113kJ/mol (with one exception of 128kJ/mol). These values are, for most cases, lower or much lower than the activation energy barriers for reactions between nitrate esters and NO (127-137kJ/mol). Consequently, the stabilizers can block the NO catalysis for the decompositions of nitrate esters.
硝酸酯的推进剂可以通过某些芳香胺实际稳定化。为了探究这一现象的机理，我们在以下方面进行了密度泛函理论（DFT）计算：（1）硝酸酯的分解（有无 NO 的催化）和（2）稳定剂与二氧化氮之间的反应（在硝酸酯的储存过程中释放 NO）。反应路径上的结构（反应物、中间体和产物）在（U）B3LYP/6-31G**水平上进行了优化。结果表明，NO 将硝酸酯分解的活化能垒降低了 11.82-17.86kJ/mol，并有效地催化了 ONO 键的断裂。然而，芳香胺作为硝酸酯的典型稳定剂，很容易消除 NO，其活化能垒低至 27-113kJ/mol（只有一个例外为 128kJ/mol）。这些值在大多数情况下，都低于或远低于硝酸酯与 NO 之间反应的活化能垒（127-137kJ/mol）。因此，稳定剂可以阻止 NO 对硝酸酯分解的催化作用。
