UNIMOLECULAR REACTION AND COLLISIONAL DEACTIVATION OF CHEMICALLY ACTIVATED 1,2-DIFLUOROETHANE PRODUCED BY MERCURY PHOTOSENSITIZATION OF CHLOROFLUOROMETHANE AT 300 DEGREES K AND 475 DEGREES K

被引:52
作者
CHANG, HW
SETSER, DW
机构
[1] Chemistry Department, Kansas State University, Manhattan
关键词
D O I
10.1021/ja50001a022
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The mercury photosensitization of CH2CIF mixed with 10% propene was used as a source of CH2F radicals for the generation of chemically activated 1,2-C2H4F2*. The pressure required for stabilization of one-half of the excited molecules was 2.0 ± 0.1 and 4.6 ± 0.2 cm at 300 and 475 °K, respectively. The results from low-pressure experiments were used to deduce the collisional deactivation efficiency of CH2C1F for 1,2-C2H4F2*. The experimental data were interpreted using a four-centered HF elimination activated complex model with specific rate constants calculated according to the RRKM formulation of unimolecular reactions with full pro-vision for the thermal distribution function of the chemically activated molecules. Comparison of calculated and experimental results indicates that the critical energy for HF elimination is 62 kcal mol−1 and that on the average 11 ± 3 kcal mol−1 of energy is removed from C2H4'F2* per collision with CH2CIF. Nonequilibrium chemical activation rate constants also were calculated for 1,1-C2H4F2 and n-C3H7F, and comparison was made with the published experimental data. The temperature dependence of the chemical activation rate constants was of special interest and the question of the temperature dependence of the collisional deactivation cross section was considered. Criticism of earlier classical Kassel treatments of the chemical activation data of these fluoroalkane systems is presented. © 1969, American Chemical Society. All rights reserved.
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页码:7648 / &
相关论文
共 56 条
[1]   MERCURY PHOTOSENSITIZED DECOMPOSITION OF FLUORINATED METHANES [J].
ALLEN, JD ;
FLOWERS, MC .
TRANSACTIONS OF THE FARADAY SOCIETY, 1968, 64 (552P) :3300-&
[2]   BROMINATION OF FLUOROALKANES .4. KINETICS OF THERMAL BROMINATION OF FLUOROFORM AND PENTAFLUOROETHANE [J].
AMPHLETT, JC ;
WHITTLE, E .
TRANSACTIONS OF THE FARADAY SOCIETY, 1968, 64 (548P) :2130-&
[3]  
[Anonymous], 1966, GAS PHASE REACTION R
[4]   PRIMARY REACTIONS IN MERCURY-PHOTOSENSITIZED DECOMPOSITION OF PROPYLENE [J].
AVRAHAMI, M ;
KEBARLE, P .
JOURNAL OF PHYSICAL CHEMISTRY, 1963, 67 (02) :354-&
[5]   HG 6(3P1) PHOTOSENSITIZATION OF CHLORODIFLUOROMETHANE [J].
BELLAS, MG ;
STRAUSZ, OP ;
GUNNING, HE .
CANADIAN JOURNAL OF CHEMISTRY, 1965, 43 (05) :1022-&
[6]   ELIMINATION OF HF FROM HOT FLUORINATED ETHANES . AN ESTIMATION OF ACTIVATION ENERGIES AND RATE PARAMETERS [J].
BENSON, SW ;
HAUGEN, G .
JOURNAL OF PHYSICAL CHEMISTRY, 1965, 69 (11) :3898-&
[8]   INTERACTIONS OF METHYL AND DIFLUOROMETHYL RADICALS AND ELIMINATION OF HF FROM HOT 1,1-DIFLUOROETHANE [J].
BRYANT, JT ;
PRITCHAR.GO .
JOURNAL OF PHYSICAL CHEMISTRY, 1967, 71 (11) :3439-&
[9]   BOND STRENGTHS IN FLUORINATED COMPOUNDS - DECOMPOSITION OF CHEMICALLY ACTIVATED 1,1,1-TRIFLUOROPROPANE [J].
CADMAN, P ;
PHILLIPS, DC ;
TROTMAND.AF .
CHEMICAL COMMUNICATIONS, 1968, (14) :796-&
[10]   ENERGY DISTRIBUTION IN REACTION PRODUCTS . PHOTOLYSIS OF CYCLOBUTANONE [J].
CAMPBELL, RJ ;
SCHLAG, EW .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1967, 89 (20) :5103-&