Deuterium isotope effects in the thermochemical decomposition of liquid 2,4,6-trinitrotoluene: application to mechanistic studies using isothermal differential scanning calorimetry analysis

Journal Article · Thu Dec 22 23:00:00 EST 1977 · J. Org. Chem.; (United States)

DOI:https://doi.org/10.1021/jo00862a006· OSTI ID:5343663

Shackelford, S A; Beckmann, J W; Wilkes, J S

The thermochemical decomposition of liquid 2,4,6-trinitrotoluene (TNT) produces a primary kinetic deuterium isotope effect when its methyl moiety is deuterium labeled. The novel integration of the deuterium isotope effect with isothermal differential scanning calorimetry analysis provides the first directly measured mechanistic evidence that carbon-hydrogen bond rupture in the TNT methyl group constitutes the rate-determining step of the thermochemical decomposition reaction. This thermochemical reaction possesses an induction period during which a single species forms from TNT and catalyzes a sustained exothermic decomposition. An expression was derived that correlated deuterium/hydrogen induction time ratios with inaccessible hydrogen/deuterium rate constant ratios during this induction period. Direct induction time measurement allowed deuterium isotope effect evaluation before interfering side reactions diluted the magnitude of the isotope effect during the latter stages of exothermic decomposition. Hydrogen donor effects suggest that the rate-determining carbon-hydrogen bond rupture proceeds homolytically. A large negative entropy of activation reveals a high degree of orderliness during the decomposition.

• Research Organization: Frank J. Seiler Research Lab., USAF Academy, CO
• OSTI ID: 5343663
• Journal Information: J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 42:26; ISSN JOCEA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
CHEMICAL EXPLOSIVES
CHEMICAL REACTION KINETICS
DEUTERIUM
EXPLOSIVES
FLUIDS
HYDROGEN ISOTOPES
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIQUIDS
NITRO COMPOUNDS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
REACTION KINETICS
STABLE ISOTOPES
TNT