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 THF at 90°C under 8 atm of He. Pressure effects on the catalytic activities depend on the nature of metal catalysts and this behavior can be explained by a different rate determining step in each system. Activation of the C-H bond of THF on metal powder aided by η² coordinated aldehydes is believed to occur first to produce electron-rich metal hydrides, which enhance the activation of the C-Cl bond of CFC-113a. Then reductive elimination follows to produce HCFC-123. This series of reactions was supported by experiments using deuterated THF and/or DMF and with p-substituted benzaldehydes.