Enzymatic synthesis of phenol polymer and its functionalization

In phosphate buffer (pH = 7.0) containing sodium dodecyl sulfate (SDS), an environmentally friendly system, enzymatic polymerization of phenol catalyzed by horseradish peroxidase (HRP) was efficiently performed. The obtained phenol polymer is partly soluble in common solvents, such as acetone, THF and DMF. IR analysis shows that the polymer is composed of phenylene and oxyphenylene units. The functionalization of the phenol polymer was performed by reacting with epoxy chloropropane and triethylene-tetramine following, and then insoluble aminated phenol polymer was obtained. The aminated phenol polymer was adopted as carrier to prepare a novel supported palladium catalyst (PP-N-Pd) for Heck reaction. PP-N-Pd shows high catalytic performance for Heck reactions of aryl iodides with acrylic acid or styrene and the yields of trans-products were higher than 90%. Under the optimized conditions, aryl bromides and activated aryl chloride also reacted with alkenes to give the yields of above 80%. XPS analysis indicates that the main coordination atom in PP-N-Pd is N and the chemical valence of palladium in PP-N-Pd is Pd2+. The novel supported catalyst also shows good recyclability for Heck reaction.