Heuristic-Based Alkaline Hydrolysis Mechanism of Nitrate Ester (Nitrocellulose Monomer) and Nitroamine (Hexogen) Compounds: Electrostatic Attraction Effect of the Nitro Group.

The alkaline hydrolysis reaction of energetic materials is important and complex. With improved performance, AMK_Mountain was used to systematically study the alkaline hydrolysis of the nitrocellulose monomer and hexogen. The reaction pathways showed that the nitrocellulose monomer produces the nitrate anion and nitrite anion differently, while hexogen only produces the nitrite anion. Electronic structure results at the M06-2X/6-311G(d,p)/PCM(Pauling) level showed that the nitrocellulose monomer and hexogen have a similar pathway in their main energy-releasing process (nitrite anion production): with electrostatic attraction effects after proton transfer, the nitrite anion dissociates from the original structure with a low barrier. Moreover, during the alkaline hydrolysis of the nitrocellulose monomer, the metastable intermediates after proton transfer may be directly generated following transition states that, structurally, tend to produce nitrite anions "proximal" to the proton transfer site and produce nitrate anions "distal" to the proton transfer site. Electronic structure analysis showed that representative metastable intermediates revealed that the charge transfer caused by electrostatic attraction may be the direct cause of these reactions.