Transfer hydrogenolysis of CFC-113a with aldehydes and metallic Fe or Ni

Highly selective transfer hydrogenolysis of CFC-113a (CF3CCl3) to HCFC-123 (CF3CHCl2) was accomplished in the presence of metal powder (Fe or Ni) in T HF at 90 degrees C under 8 arm of He. Pressure effects on the catalytic act ivities depend on the nature of metal catalysts and this behavior can be ex plained by a different rate determining step in each system. Activation of the C-H bond of THF on metal powder aided by eta(2) coordinated aldehydes i s believed to occur first to produce electron-rich metal hydrides, which en hance the activation of the C-Cl bond of CFC-113a. Then reductive eliminati on follows to produce HCFC-123, This series of reactions was supported by e xperiments using deuterated THF and/or DMF and with p-substituted benzaldeh ydes. (C) 1999 Elsevier Science S.A. All rights reserved.