Exploration of acid–base geometric influence on cooperative activation for aldol reaction

Bifunctionalized material with organized pairs of carboxylic acid and primary amine structurally similar to β3-amino acid derivatives has been prepared through post-grafted approach. Then the organized acid–base bifunctionalized material and the base monofunctionalized material were used as catalysts in aldol reaction to study the influence of the acid–base geometry on acid–base cooperativity. The catalytic result using acid–base bifunctionalized material towards aldol reaction was almost as same as the result obtained with the monofunctional amino catalyst, indicating that cooperative activation is not able to act efficiently unless the acid and the base active centers are positioned with appropriate geometry for the aldol reaction (e.g. about 2.6 Å).

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► Organized acid–base bifunctionalized material.
► Effective radius for acid–base cooperativity.
► Influence of acid–base geometry on cooperativity.