Abstraction of chlorine atoms from chloroalkanes. III. The kinetics of liquid phase reactions of trichlorosilyl radicals with chloromethanes

✍ Scribed by R. Aloni; A. Horowitz; L. A. Rajbenbach

• Publisher: John Wiley and Sons
• Year: 1976
• Tongue: English
• Weight: 617 KB
• Volume: 8
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550080504

✦ Synopsis

The kinetics of chlorine atom abstraction from the chloromethanea (ClM), CCl,, CHCl,, CHZC12, and CH3Cl by radiolytically generated trichlorosilyl radicals was studied in the liquid phase by a competitive method. Arrhenius parameters of chlorine atom abstraction from chloroinethanes relative to that of bromine atom abstraction from cyclohexyl bromide (RBr) were as follows:

ItBr) (kcal/mole) Range (OK) cc1, 0.85 k 0.19 2.53 f 0.3.5 348-463 CHC13 0.05 f 0.10 3.40 f 0.18 273-423 CHzCl, 0.20 =k 0.22 4.60 =k 0.62 298-423 273-398 CH&1 -0.63 f 0.27 5.18 f 0.43

The error limits are two standard deviations ( 2 ~) from least mean square Arrhenius plots. From the linear correlation between Ecl values derived from the reactions of SiC1, and cyclohexyl radicals with the ClM series it is estimated that Ecl (R + CH,CI) 'v 16 kcal/mole.

In addition the relative Arrhenius parameters for the hydrogen atom abstraction from SiHC13 and chlorine at.om abstraction from CC14 by cyclohexyl radicals were obtained log A H / A CI = 0.12 f 0.15 and E H -Ecl = 0.24 f 0.26. The E E -Ecl value was combined with existing data on E(K + Cc14) to yield the E H ( R + SiHCl,) value.