Dechlorination of 4-chlorobiphenyl using NaBH4 at 120-310°C in high boiling inert solvents with and without LiCl

Article abstract of DOI:10.1016/S0040-4039(97)01495-0

Dechlorination of 4-chlorobiphenyl with NaBH₄ in high boiling inert solvents from 120-310°C were studied. Complete dechlorination occurred in NaBH₄/tetraglyme at 310°C in one hour. Adding LiCl to NaBH₄ promoted dechlorination in di-, tri, and tetraglyme respectively at 120-135°C. The rate was significantly enhanced when NaBH₄, LiCl, and glyme were prestirred at room temperature for 20 minutes before heating to 120-135°C. At equivalent conditions, dechlorination rates followed the order: tetraglyme > triglyme > diglyme. 4-Chlorobiphenyl dechlorination failed using NaBH₄/diphenyl ether. In pentamethyldiethylenetriamine 3- and 4-N,N-dimethylaminobiphenyl was produced through a benzyne intermediate.