Reductive dehalogenation of aryl halides over palladium catalysts deposited on SBA-15 type molecular sieve modified with amine donor groups
Abstract
Supported palladium catalysts prepared from palladium(II) acetate and SBA-15 type molecular sieve modified with N-[2-(diethylamino)ethyl]-3-aminopropyl donor groups efficiently catalyse reductive dehalogenation of various bromo- and iodobenzenes with in situ formed triethylammonium formate as the hydrogen source. Since the corresponding chlorobenzenes react at considerably lower rates while fluorobenzenes remain unaffected, the catalytic system can be utilised for selective dehalogenations of multiply halogenated substrates.
Compared with Pd/C tested earlier [N.A. Cortese, R.F.
Heck, J. Org.
Chem. 42 (1977) 3491], the catalysts deposited over modified SBA-15 are more reactive. Besides, they exert rather minor leaching of the metal component (8.4% during five consecutive runs with 0.5 mol.% Pd with respect to the substrate) and maintain their high activity during repeated use.