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Author(s):   Seetula, J.A.
Title:   Kinetics of the R+HBr <-> RH+Br (R = CH2Br, CHBrCl or CCl3) equilibrium. Thermochemistry of the CH2Br and CHBrCl radicals
Journal:   Phys. Chem. Chem. Phys.
Volume:   5
Page(s):   849 - 855
Year:   2003
Reference type:   Journal article
Squib:   2003SEE849-855

Reaction:   ·CCl3 + HBrCHCl3 + Br·
Reaction order:   2
Temperature:   787 K
Pressure:  5.90E11 bar
Rate expression:   6.0x10-15 [±1.0x10-15 cm3/molecule s]
Rate constant is an upper limit.
Bath gas:   He
Category:  Experiment
Data type:   Absolute value measured directly
Pressure dependence:   Rate constant is pressure independent
Experimental procedure:   Static or low flow - Data taken vs time
Excitation technique:   Flash photolysis (laser or conventional)
Time resolution:   In real time
Analytical technique:   Mass spectrometry
Comments:   Halomethyl radicals CH2Br, CHBrCl, and CCl3 produced by 248 nm excimer laser photolysis of CH2Br2, CHBr2Cl, and CBrCl3, respectively. Radical concentrations detected as a function of time following photolysis laser pulse using photoionization mass spec. Determined heats of formation and entropy of the radicals using measured rate constants and literature values (expt and theory) for the reverse reactions. Also calculated barriers for the reverse reactions using MP2/6-31G(d,p). Experimentally derived DfHo,298 for CH2Br and CHBrCl are 171.1(2.7) and 143(6) kJ/mol, respectively. The value for CH2Br is in good agreement with other in the literature. The value for CHBrCl is the first reported experimentally derived value.

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