Comprehensive Investigations of Kinetics of Alkaline Hydrolysis of TNT (2,4,6-Trinitrotoluene), DNT (2,4-Dinitrotoluene), and DNAN (2,4-Dinitroanisole)

Abstract

Combined experimental and computational techniques were used to analyze multistep chemical reactions in the alkaline hydrolysis of three nitroaromatic compounds: 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), and 2,4-dinitroanisole (DNAN). The study reveals common features and differences in the kinetic behavior of these compounds. The analysis of the predicted pathways includes modeling of the reactions, along with simulation of UV-vis spectra, experimental monitoring of reactions using LC/MS techniques, development of the kinetic model by designing and solving the system of differential equations, and obtaining computationally predicted kinetics for decay and accumulation of reactants and products. Obtained results suggest that DNT and DNAN are more resistant to alkaline hydrolysis than TNT. The direct substitution of a nitro group by a hydroxide represents the most favorable pathway for all considered compounds. The formation of Meisenheimer complexes leads to the kinetic first-step intermediates in the hydrolysis of TNT. Janovsky complexes can also be formed during hydrolysis of TNT and DNT but in small quantities. Methyl group abstraction is one of the suggested pathways of DNAN transformation during alkaline hydrolysis.

One-Step Instantaneous Detection of Multiple Military and Improvised Explosives Facilitated by Colorimetric Reagent Design

“…It is considered that because of the strongly electron-withdrawing nature of the nitro groups and the electron-donating nature of methyl group, the C1 carbon on the aromatic ring of TNT or DNT is highly electron-deficient and can serve as an electron acceptor . Thus, it is highly possible that C 3 H 7 O – , which is a nucleophile, would attack C1 carbon to form stable colored Jackson–Meisenheimer complexes, such as TNT-C 3 H 7 O – and DNT-C 3 H 7 O – . It can be further confirmed by the electrostatic potential distribution (Figure e) that the nearby C1 carbon owning a maximum point (red area) of electrostatic potential will be more vulnerable to attack by the oxygen in C 3 H 7 O – owning minimum points (blue area) of electrostatic potential as a nucleophile, which is quite identical to the previous report .…”

“…32 Thus, it is highly possible that C 3 H 7 O − , which is a nucleophile, would attack C1 carbon to form stable colored Jackson−Meisenheimer complexes, such as TNT-C 3 H 7 O − and DNT-C 3 H 7 O − . 38 It can be further confirmed by the electrostatic potential distribution (Figure 2e) that the nearby C1 carbon owning a maximum point (red area) of electrostatic potential will be more vulnerable to attack by the oxygen in C 3 H 7 O − owning minimum points (blue area) of electrostatic potential as a nucleophile, which is quite identical to the previous report. 32 It should be noted that because the number of nitro groups is different on TNT and DNT, the electron-deficient degree of C1 carbon in TNT and DNT is different.…”

Alkaline hydrolysis of hexahydro-1,3,5-trinitro-1,3,5-triazine: M06-2X investigation

“…The relevant stationary points (intermediates, transition states, and products) in aqueous solution were fully optimized at the PCM(Pauling)/M06-2X/6-311++G(d,p) level (Cossi et al, 1996;Sousa et al, 2007;Zhao and Truhlar, 2008). The functional M06-2X has been successfully used in our studies of alkaline hydrolysis of nitroaromatics (Hill et al, 2012;Sviatenko et al, 2014). It was also shown that Pauling radii should be used for appropriate reproduction of solvation effects (Hill et al, 2012).…”

“…This procedure is semi-empirical since it is based on available experimental data, and allows the experimentally-determined data to be significantly extended by addition of computationally predicted data. This procedure was successfully applied to the prediction of kinetics of alkaline hydrolysis of such energetic materials as trinitrotoluene, dinitrotoluene and dinitroanisole (Sviatenko et al, 2014). The procedure consists of two major stages.…”

“…The final step of the first stage is identification of the most probable pathway from the steps obtained, considering both kinetic and thermodynamic controls. The second step uses the same approach as step one with inclusion of the influence of specific hydration to create a more accurate model (Sviatenko et al, 2014). Only possible chemical reactions from step one for which kinetic equations and chemical kinetics were obtained are used in step two.…”