Ab Initio Chemical Kinetics for Nitrogen Tetroxide Reactions with 1, 1‐ and 1, 2‐Dimethylhydrazines. Issue 9 (3rd June 2020)

• Record Type: Journal Article
• Authors: Le Huyen, Trinh; Raghunath, Putikam; Chang Lin, Ming
• Is Part Of: Propellants, explosives, pyrotechnics. Volume 45:Issue 9(2020)
• Page Start: 1478
• Page End: 1486
• Publication Date: 2020-06-03
• Subjects: N2O4 reactions with dimethylhydrazine -- Roaming-like transition states -- Kinetics -- Mechanisms -- Hypergolic ignition; Propellants -- Periodicals; Explosives -- Periodicals; 662.2
• DOI: 10.1002/prep.201900426
• Languages: English
• ISSNs: 0721-3115

Abstract

Abstract: This work employed the quantum‐chemical method at the CCSD(T)/6‐311+G(3df, 2p)//B3LYP/6‐311+G(3df, 2p) level to study the mechanisms and kinetics of N2 O4 (NTO) with H2 NN(CH3 )2 and CH3 NHNHCH3 hypergolic initiation reactions, the processes critical to the chemical rocket propulsion of the N2 O4 ‐hydrazine propellant systems. The reaction of N2 O4 with the dimethylhydrazines (DMHZ's) can be started by the fast reaction of DMHZ's with ONONO2, taking place after the novel N2 O4 →ONONO2 transformation with each of DMHZ's as a spectator within the NTO‐DMHZ collision complexes, through loose, roaming‐like transition states during the bimolecular encounters. The barriers for such isomerization processes were found to be 7.2 and 9.9 kcal/mol for H2 NN(CH3 )2 and CH3 NHNHCH3, respectively. The kinetics of these reactions have been computed in the temperature range 200–2000 K; the results indicate that under the ambient temperature and pressure condition, the half‐life of NTO in the presence of an excess amount of H2 NN(CH3 )2 is predicted to be 3.3×10 −5 s. The results of a similar estimate for CH3 NHNHCH3 is about 2 orders of magnitude longer; both estimates indicate that very effective hypergolic reactions can occur upon mixing in these systems. Abstract :