TY - JOUR
T1 - Thermal decomposition of 2,2-bis(difluoroamino) propane studied by FTIR spectrometry and quantum chemical calculations
T2 - The primary dissociation kinetics and the mechanism for decomposition of the (CH3)2CNF2 radical
AU - Park, J.
AU - Chakraborty, D.
AU - Jamindar, S.
AU - Xia, W. S.
AU - Lin, Ming-Chang
AU - Bedford, C.
PY - 2002/2/25
Y1 - 2002/2/25
N2 - The kinetics of the thermal decomposition of 2,2-bis(difluoroamino) propane (BDFP) has been studied by pyrolysis/FTIR spectrometry at temperatures between 528 and 553 K using toluene as radical scavenger. The disappearance of BDFP was found to follow the first-order kinetics with the rate constant, k1 = 1016.0±0.7 exp[-(24200 ± 840)/T] s-1, which agrees closely with the expression obtained by Fokin et al. [Dokl. Akad. Nauk. 332 (1993) 735], k1 = 1015.60 exp(-23600/T) s-1. The measured large A-factor supports the earlier conclusion that the primary fragmentation process corresponds to the breaking of one of the two NF2 groups. The measured activation energy is also consistent with the predicted first C-N bond dissociation energy, 44-48 kcal/mol, by the hybrid density-functional theory and that evaluated by variational RRKM calculations fitting the observed rate constant, 47.9 kcal/mol. The 2-difluoroamino propyl radical, (CH3)2CNF2, was predicted to be thermally unstable, producing readily F atoms and HF molecules via the (CH3)2CFNF intermediate. The quantum-chemically predicted mechanisms for the fragmentation of (CH3)2C(NF2)2 and (CH3)2CNF2 agree with the product distribution reported by Ross and coworkers.
AB - The kinetics of the thermal decomposition of 2,2-bis(difluoroamino) propane (BDFP) has been studied by pyrolysis/FTIR spectrometry at temperatures between 528 and 553 K using toluene as radical scavenger. The disappearance of BDFP was found to follow the first-order kinetics with the rate constant, k1 = 1016.0±0.7 exp[-(24200 ± 840)/T] s-1, which agrees closely with the expression obtained by Fokin et al. [Dokl. Akad. Nauk. 332 (1993) 735], k1 = 1015.60 exp(-23600/T) s-1. The measured large A-factor supports the earlier conclusion that the primary fragmentation process corresponds to the breaking of one of the two NF2 groups. The measured activation energy is also consistent with the predicted first C-N bond dissociation energy, 44-48 kcal/mol, by the hybrid density-functional theory and that evaluated by variational RRKM calculations fitting the observed rate constant, 47.9 kcal/mol. The 2-difluoroamino propyl radical, (CH3)2CNF2, was predicted to be thermally unstable, producing readily F atoms and HF molecules via the (CH3)2CFNF intermediate. The quantum-chemically predicted mechanisms for the fragmentation of (CH3)2C(NF2)2 and (CH3)2CNF2 agree with the product distribution reported by Ross and coworkers.
KW - 2,2-Bis(difluoroamino) propane
KW - Propellants
KW - Thermal decomposition
UR - http://www.scopus.com/inward/record.url?scp=0037170243&partnerID=8YFLogxK
U2 - 10.1016/S0040-6031(01)00781-X
DO - 10.1016/S0040-6031(01)00781-X
M3 - Article
AN - SCOPUS:0037170243
SN - 0040-6031
VL - 384
SP - 101
EP - 111
JO - Thermochimica Acta
JF - Thermochimica Acta
IS - 1-2
ER -