Overcoming acid–base copolymer neutralization using mesoporous carbon and its catalytic activity in the tandem deacetalization–Knoevenagel condensation reaction

Acid–base copolymer materials are of considerable interest because of their fundamental
implications for acid–base bifunctional catalysis applications. However,
quenching the acid and base sites of the copolymer with each other in free radical
polymerizations is still challenging. Herein, we demonstrate that the polymerization
of styrenesulfonic acid-co-4-vinylpyridine into the mesoporous carbon material (i.e.,
CMK-3) can control the chain growth polymerization and result in decreasing the
interaction of the acid–base sites. The results showed that by using CMK-3, 40% of
the acid and base sites of the copolymer remain in their original form while 60% of
acid and base sites convert to the pyridinium and sulfonate forms. Furthermore, it
is demonstrated that this material can be processed as a heterogeneous bifunctional
acid–base catalyst in the tandem one-pot acid–base reaction (i.e., deacetalization–
Knoevenagel condensation reaction) with a high catalytic activity in aqueous media.