Reactions of trichloromethyl radicals with organosilicon compounds

✍ Scribed by J. A. Rice; J. J. Treacy; H. W. Sidebottom

• Publisher: John Wiley and Sons
• Year: 1984
• Tongue: English
• Weight: 625 KB
• Volume: 16
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550161205

✦ Synopsis

The photolysis of carbon tetrachloride in the presence of a number of organosilicon compounds has been investigated in the gas phase. The products obtained from the photolysis experiments were those expected from a chain reaction in which trichloromethyl radicals abstract hydrogen atoms from the organosilane. Arrhenius parameters for hydrogen atom transfer were determined relative to those for trichloromethyl radical combination.

SiH log,,&L/mol s ) E, kcal/mol (CH,),SiH 8.7 t 0.3 7.9 t 0.5 (CH,),CISiH 8.7 t 0.3 9.1 t 0.5 CH,Cl,SiH 8.7 t 0.3 9.5 t 0.6 C1,SiH 8.6 t 0.3 9.7 t 0.5 (C,H,O),SiH 8.4 t 0.4 10.1 t 0.8 CC1,. + R,SiCH, -CHCl, + R3SiCH,. R,SiCH, log,&A,,(L/mol s) El, kcal/mol (CH,),SiCH, 9.0 t 0.3 12.9 t 0.6 (CH,),ClSiCH, 8.8 t 0.7 13.2 t 1.6 CH,Cl,SiCH, 8.9 t 0.2 14.1 t 0.6 Cl,SiCH, 8.7 t 0.3 14.2 t 0.6 CH,F,SiCH, 8.4 t 0.4 14.3 t 1.0 (CH,),BrSiCH3

8.9 ? 0.3 13.0 2 0.6

The activation energies for the reaction of methyl, trifluoromethyl, and trichloromethyl radicals with organosilicon compounds are compared and the results rationalized in terms of polar effects.