Alkaline hydrolysis of trinitrotoluene, TNT

Andrew Mills, Alison Seth, Gavin Peters

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The kinetics of the alkaline hydrolysis of trinitrotoluene, TNT, in an aqueous solution is a possible approach to destroying the active agent in unwanted munitions. The kinetics are shown to have a rapid initial step, step A, in which a highly coloured species, X (max=450 nm) is formed via an equilibrium reaction: TNT+OH-X. The bimolecular rate constant for the forward part of this equilibrium process, k1, is: 0.099±0.004, 0.32±0.02 and 1.27±0.05 dm3 mol-1 s-1, at 25, 40 and 60°C, respectively. The activation energy for the forward process is 60 kJ mol-1. The first-order rate constant for the reverse of this process, k-1, is: (5.3±2.6)×10-4, (1.2±1.0)×10-3 and (7.7±2.9)×10-3 s-1 at 25, 40 and 60°C, respectively. The activation energy for the overall equilibrium process (k1/k-1) is ca.-5 kJ mol-1. The subsequent alkaline hydrolysis of X to form the final product P, i.e. step B, is much slower than step A and appears to comprise two processes coupled in series, i.e. steps B1 (X+2OH-Z) and B2 (Z+OH-P). At 25°C, Step B1 appears rate determining throughout the decay process. At 45°C and, more so, at 60°C, step B appears increasingly biphasic with increasing alkaline concentrations, as step B2 begins to compete with step B1 for position as the rate determining step. The trimolecular rate constant for step B1 is: 0.017±0.001, 0.0085±0.0002 and 0.0011±0.0001 dm6 mol-2 s-1 at 25, 40 and 60°C, respectively, and the process has an activation energy of 64 kJ mol-1. The transition from uniform kinetics, described by step B1, to mixed kinetics, described by steps B1 and B2, as the reaction temperature and alkali concentration are increased most likely occurs because (a) step B2 has a lower activation energy than B1, although it was not possible to measure the former parameter, and (b) step B2 has a lower (1st) order dependence upon [OH-] compared with that of step B1 (2nd). The bimolecular rate constant for step B2 is 0.0035±0.03 dm3 mol-1 s-1 at 60°C. A brief NMR study of the initial hydrolysis product in water, acetone and chloroform, coupled with UV/visible spectra, provides evidence that species X is a Meisenheimer complex.
LanguageEnglish
Pages3921-3927
Number of pages6
JournalPhysical Chemistry Chemical Physics
Volume5
Issue number18
DOIs
Publication statusPublished - 2003

Fingerprint

Trinitrotoluene
trinitrotoluene
hydrolysis
Hydrolysis
Rate constants
Activation energy
Kinetics
Alkalies
Chloroform
Acetone
Nuclear magnetic resonance
activation energy
Water
kinetics
hydroxide ion
Temperature

Keywords

  • PHANEROCHAETE-CHRYSOSPORIUM
  • 2
  • 4
  • 6-TRINITROTOLUENE TNT
  • CONTAMINATED SOILS
  • ANION

Cite this

Mills, Andrew ; Seth, Alison ; Peters, Gavin. / Alkaline hydrolysis of trinitrotoluene, TNT. In: Physical Chemistry Chemical Physics. 2003 ; Vol. 5, No. 18. pp. 3921-3927.
@article{60478b9155744924b3acdc36adf58b85,
title = "Alkaline hydrolysis of trinitrotoluene, TNT",
abstract = "The kinetics of the alkaline hydrolysis of trinitrotoluene, TNT, in an aqueous solution is a possible approach to destroying the active agent in unwanted munitions. The kinetics are shown to have a rapid initial step, step A, in which a highly coloured species, X (max=450 nm) is formed via an equilibrium reaction: TNT+OH-X. The bimolecular rate constant for the forward part of this equilibrium process, k1, is: 0.099±0.004, 0.32±0.02 and 1.27±0.05 dm3 mol-1 s-1, at 25, 40 and 60°C, respectively. The activation energy for the forward process is 60 kJ mol-1. The first-order rate constant for the reverse of this process, k-1, is: (5.3±2.6)×10-4, (1.2±1.0)×10-3 and (7.7±2.9)×10-3 s-1 at 25, 40 and 60°C, respectively. The activation energy for the overall equilibrium process (k1/k-1) is ca.-5 kJ mol-1. The subsequent alkaline hydrolysis of X to form the final product P, i.e. step B, is much slower than step A and appears to comprise two processes coupled in series, i.e. steps B1 (X+2OH-Z) and B2 (Z+OH-P). At 25°C, Step B1 appears rate determining throughout the decay process. At 45°C and, more so, at 60°C, step B appears increasingly biphasic with increasing alkaline concentrations, as step B2 begins to compete with step B1 for position as the rate determining step. The trimolecular rate constant for step B1 is: 0.017±0.001, 0.0085±0.0002 and 0.0011±0.0001 dm6 mol-2 s-1 at 25, 40 and 60°C, respectively, and the process has an activation energy of 64 kJ mol-1. The transition from uniform kinetics, described by step B1, to mixed kinetics, described by steps B1 and B2, as the reaction temperature and alkali concentration are increased most likely occurs because (a) step B2 has a lower activation energy than B1, although it was not possible to measure the former parameter, and (b) step B2 has a lower (1st) order dependence upon [OH-] compared with that of step B1 (2nd). The bimolecular rate constant for step B2 is 0.0035±0.03 dm3 mol-1 s-1 at 60°C. A brief NMR study of the initial hydrolysis product in water, acetone and chloroform, coupled with UV/visible spectra, provides evidence that species X is a Meisenheimer complex.",
keywords = "PHANEROCHAETE-CHRYSOSPORIUM, 2, 4, 6-TRINITROTOLUENE TNT, CONTAMINATED SOILS, ANION",
author = "Andrew Mills and Alison Seth and Gavin Peters",
year = "2003",
doi = "10.1039/b304616h",
language = "English",
volume = "5",
pages = "3921--3927",
journal = "Physical Chemistry Chemical Physics",
issn = "1463-9076",
number = "18",

}

Alkaline hydrolysis of trinitrotoluene, TNT. / Mills, Andrew; Seth, Alison; Peters, Gavin.

In: Physical Chemistry Chemical Physics, Vol. 5, No. 18, 2003, p. 3921-3927.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Alkaline hydrolysis of trinitrotoluene, TNT

AU - Mills, Andrew

AU - Seth, Alison

AU - Peters, Gavin

PY - 2003

Y1 - 2003

N2 - The kinetics of the alkaline hydrolysis of trinitrotoluene, TNT, in an aqueous solution is a possible approach to destroying the active agent in unwanted munitions. The kinetics are shown to have a rapid initial step, step A, in which a highly coloured species, X (max=450 nm) is formed via an equilibrium reaction: TNT+OH-X. The bimolecular rate constant for the forward part of this equilibrium process, k1, is: 0.099±0.004, 0.32±0.02 and 1.27±0.05 dm3 mol-1 s-1, at 25, 40 and 60°C, respectively. The activation energy for the forward process is 60 kJ mol-1. The first-order rate constant for the reverse of this process, k-1, is: (5.3±2.6)×10-4, (1.2±1.0)×10-3 and (7.7±2.9)×10-3 s-1 at 25, 40 and 60°C, respectively. The activation energy for the overall equilibrium process (k1/k-1) is ca.-5 kJ mol-1. The subsequent alkaline hydrolysis of X to form the final product P, i.e. step B, is much slower than step A and appears to comprise two processes coupled in series, i.e. steps B1 (X+2OH-Z) and B2 (Z+OH-P). At 25°C, Step B1 appears rate determining throughout the decay process. At 45°C and, more so, at 60°C, step B appears increasingly biphasic with increasing alkaline concentrations, as step B2 begins to compete with step B1 for position as the rate determining step. The trimolecular rate constant for step B1 is: 0.017±0.001, 0.0085±0.0002 and 0.0011±0.0001 dm6 mol-2 s-1 at 25, 40 and 60°C, respectively, and the process has an activation energy of 64 kJ mol-1. The transition from uniform kinetics, described by step B1, to mixed kinetics, described by steps B1 and B2, as the reaction temperature and alkali concentration are increased most likely occurs because (a) step B2 has a lower activation energy than B1, although it was not possible to measure the former parameter, and (b) step B2 has a lower (1st) order dependence upon [OH-] compared with that of step B1 (2nd). The bimolecular rate constant for step B2 is 0.0035±0.03 dm3 mol-1 s-1 at 60°C. A brief NMR study of the initial hydrolysis product in water, acetone and chloroform, coupled with UV/visible spectra, provides evidence that species X is a Meisenheimer complex.

AB - The kinetics of the alkaline hydrolysis of trinitrotoluene, TNT, in an aqueous solution is a possible approach to destroying the active agent in unwanted munitions. The kinetics are shown to have a rapid initial step, step A, in which a highly coloured species, X (max=450 nm) is formed via an equilibrium reaction: TNT+OH-X. The bimolecular rate constant for the forward part of this equilibrium process, k1, is: 0.099±0.004, 0.32±0.02 and 1.27±0.05 dm3 mol-1 s-1, at 25, 40 and 60°C, respectively. The activation energy for the forward process is 60 kJ mol-1. The first-order rate constant for the reverse of this process, k-1, is: (5.3±2.6)×10-4, (1.2±1.0)×10-3 and (7.7±2.9)×10-3 s-1 at 25, 40 and 60°C, respectively. The activation energy for the overall equilibrium process (k1/k-1) is ca.-5 kJ mol-1. The subsequent alkaline hydrolysis of X to form the final product P, i.e. step B, is much slower than step A and appears to comprise two processes coupled in series, i.e. steps B1 (X+2OH-Z) and B2 (Z+OH-P). At 25°C, Step B1 appears rate determining throughout the decay process. At 45°C and, more so, at 60°C, step B appears increasingly biphasic with increasing alkaline concentrations, as step B2 begins to compete with step B1 for position as the rate determining step. The trimolecular rate constant for step B1 is: 0.017±0.001, 0.0085±0.0002 and 0.0011±0.0001 dm6 mol-2 s-1 at 25, 40 and 60°C, respectively, and the process has an activation energy of 64 kJ mol-1. The transition from uniform kinetics, described by step B1, to mixed kinetics, described by steps B1 and B2, as the reaction temperature and alkali concentration are increased most likely occurs because (a) step B2 has a lower activation energy than B1, although it was not possible to measure the former parameter, and (b) step B2 has a lower (1st) order dependence upon [OH-] compared with that of step B1 (2nd). The bimolecular rate constant for step B2 is 0.0035±0.03 dm3 mol-1 s-1 at 60°C. A brief NMR study of the initial hydrolysis product in water, acetone and chloroform, coupled with UV/visible spectra, provides evidence that species X is a Meisenheimer complex.

KW - PHANEROCHAETE-CHRYSOSPORIUM

KW - 2

KW - 4

KW - 6-TRINITROTOLUENE TNT

KW - CONTAMINATED SOILS

KW - ANION

UR - http://www.rsc.org/Publishing/Journals/CP/article.asp?doi=b304616h

U2 - 10.1039/b304616h

DO - 10.1039/b304616h

M3 - Article

VL - 5

SP - 3921

EP - 3927

JO - Physical Chemistry Chemical Physics

T2 - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 18

ER -