In Silico Alkaline Hydrolysis of Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine: Density Functional Theory Investigation

Abstract

HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), an energetic material used in military applications, may be released to the environment during manufacturing, transportation, storage, training, and disposal. A detailed investigation of a possible mechanism of alkaline hydrolysis, as one of the most promising methods for HMX remediation, was performed by computational study at PCM(Pauling)/M06-2X/6-311++G(d,p) level. Obtained results suggest that HMX hydrolysis at pH 10 represents a highly exothermic multistep process involving initial deprotonation and nitrite elimination, hydroxide attachment accompanied by cycle cleavage, and further decomposition of cycle-opened intermediate to the products caused by a series of C-N bond ruptures, hydroxide attachments, and proton transfers. Computationally predicted products of HMX hydrolysis such as nitrite, 4-nitro-2,4-diazabutanal, formaldehyde, nitrous oxide, formate, and ammonia correspond to experimentally observed species. Based on computed reaction pathways for HMX decomposition by alkaline hydrolysis, the kinetics of the entire process was modeled. Very low efficiency of this reaction at pH 10 was observed. Computations predict significant increases (orders of magnitude) of the hydrolysis rate for hydrolysis reactions undertaken at pH 11, 12, and 13.

Fabrication and Characterization of Nanoenergetic Hollow Spherical Hexanitrostibene (HNS) Derivatives

“…For piperazine segments of nanoenergetic derivatives, four piperazine carbon atoms have only one resonance peak shift from raw piperazine (the resonance peak at 48 ppm), indicating that these carbon atoms are in the same chemical environment. Many complex chemical reactions for nitro-aromatic compounds are involved in alkaline environments: HNS is a typical nitro-aromatic compound and piperazine is an alkaline substance [ 36 ]. Under this reaction condition, the piperazine radicals are formed easily because of the properties of organic alkaline substances.…”

Prediction Models on pKa and Base-Catalyzed Hydrolysis Kinetics of Parabens: Experimental and Quantum Chemical Studies

“…The integral equation formalism of the polarized continuum model (IEFPCM) 49 and SMD 40 were widely used implicit solvation models and have been testified with good performance in many studies on hydrolysis. 23,25,27,28 These two implicit solvation models were initially tested for the reference compounds as well. Effects of explicit water molecules on the hydrolysis kinetics were also evaluated.…”

“…As B3LYP and M06-2X functionals have been previously employed to investigate hydrolysis of chemicals with satisfactory performance, ,,, they were initially evaluated by predicting the k h , k B_PB , and k B_PB – values for the six reference compounds, in conjunction with different basis sets [6-311++G­(d,p) and 6-311++G­(2d,2p)]. The integral equation formalism of the polarized continuum model (IEFPCM) and SMD were widely used implicit solvation models and have been testified with good performance in many studies on hydrolysis. ,,, These two implicit solvation models were initially tested for the reference compounds as well. Effects of explicit water molecules on the hydrolysis kinetics were also evaluated.…”

“…Unavailability of authentic chemical standards for some parabens also limits the experimental determination. Quantum chemical calculation may overcome the limitation of experimental determination on hydrolysis kinetics. − Therefore, it is desirable to employ quantum chemical calculation to predict the thermodynamic and kinetics values.…”

Development of Prediction Models on Base-Catalyzed Hydrolysis Kinetics of Phthalate Esters with Density Functional Theory Calculation

“…37 Sviatenko et al employed DFT to unveil the mechanism of alkaline hydrolysis and degradation rates of an energetic material octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and found that DFTpredicted products corresponded to experimental species. 33 Therefore, it is feasible to investigate PAE hydrolysis pathways and kinetics by DFT calculation.…”