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Title: Kinetics of the Reaction of C2Cl3 with Cl2
Journal: J. Phys. Chem. A
Volume: 107
Page(s): 1776 - 1778
Year: 2003
Reference type: Journal article
Squib: 2003KOS/BRY1776-1778
Reaction:
Cl2 + CCl2=CCl → C2Cl4 + Cl
Reaction order:
2
Temperature:
299 - 668
K
Pressure: 3.00E11 - 1.20E12 bar
Rate expression:
5.39x10-13 [cm3/molecule s] (T/298 K)0.87 e-457 [J/mole]/RT
Uncertainty:
1.1
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:
C2Cl3 was produced by pulsed laser photolysis of C2Cl4 at 248nm in He bath gas in the presence of a large excess of Cl2. Decays of C2Cl3 were followed in real time with photoionization mass spectrometry. No pressure dependence of the rate data was observed. Rate constants were determined at eighteen temperatures beween 299 and 668 K and significant curvature in the Arrhenius plot was observed. The analytical rate expression matches the individual measurements within about 5%. The observed reaction rate is much larger than estimated in previous kinetic models.
The authors carried out ab initio calculations and attempted to create a transition-state model to extrapolate the rate expression. They found the optimized energy of the transition state to be 4.15 kJ/mol below the energy of the reactants, suggesting the formation of a loosely-bound intermediate complex along the reaction path. They were unable to recommend a model useful for extrapolation of the experimental data.
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Rate constant values calculated from the Arrhenius expression:
| T (K) | k(T) [cm3/molecule s] |
|---|---|
| 299 | 4.49E-13 |
| 300 | 4.51E-13 |
| 325 | 4.90E-13 |
| 350 | 5.29E-13 |
| 375 | 5.68E-13 |
| 400 | 6.06E-13 |
| 425 | 6.44E-13 |
| 450 | 6.82E-13 |
| 475 | 7.20E-13 |
| 500 | 7.57E-13 |
| 525 | 7.94E-13 |
| 550 | 8.30E-13 |
| 575 | 8.67E-13 |
| 600 | 9.03E-13 |
| 625 | 9.39E-13 |
| 650 | 9.75E-13 |
| 668 | 1.00E-12 |