Poly(ethylene glycols) and Poly(ethylene glycol)-Grafted Copolymers Are Extraordinary Catalysts for Dehydrohalogenation under Two-Phase and Three-Phase Conditions

Article abstract of DOI:10.1021/jo00150a011

Poly(ethylene glycols) 3> possess remarkably high activity as catalysts for dehydrohalogenation in organic-aqueous hydroxide two-phase systems, relative to classical phase-transfer agents, i. e., benzyltriethylammonium chloride and 18-crown-6.The importance of terminal hydroxyl groups together with the abrupt increase in catalyst activity and concentration in the organic layer on going from n=2 to n=3 and from n=3 to n=4 suggests the involvement of novel polymeric alkoxides I and/or hydroxides II.Moreover, the fact that maximum activity is obtained with n<*>5 implies that an "18-crown-6-like" structure occuring at the terminus of the polymer chain is optimal for catalysis.Poly(ethylene glycols) grafted to cross-linked polystyrene display reasonably high activity.In preparative-scale conversions, such triphase catalysts can be recovered quantitatively by simple filtration and reused without significant loss in activity.