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Synthesis of N-butylphthalimide catalyzed by quaternary phosphonium salt-type triphase catalysts based on cross-linked polystyrene microspheres



Chloroacylation reactions of cross-linked polystyrene (CPS) microspheres were conducted with two kinds of ω-chloroacyl chlorides, chloroacetyl chloride, and 4-chlorobutyryl chloride as reagent, respectively, and the chloromethylation reaction of CPS microspheres was also performed using 1,4-bis (chloromethoxy) butane as reagent, obtaining three kinds of modified CPS microspheres on which the exchangeable chlorine atoms were introduced. Subsequently, the reactions of these modified microspheres with triphenylphosphine were carried out, respectively, and three kinds of quaternary phosphonium salt (QPS)-type triphase catalysts (TPC) were prepared. These catalysts were used in the N-alkylation reaction of phthalimide, namely the reaction of phthalimide in water phase with 1-bromobutane in organic phase, resulting in N-butylphthalimide. The effects of main reaction conditions on the triphase-transfer catalysis reaction were examined, and the relationship between the structure and catalytic activity for these TPC was investigated. The experimental results indicate that the prepared QPS-type TPC are effective for the N-alkylation reaction of phthalimide carried out between oil phase and water phase. The polarity of the organic solvent and the temperature affect the reaction rate greatly. The result of the reaction in nitrobenzene having the highest polarity among the used several solvents is the best. It will make the reaction to speed up to raise temperature. The chemical structures of the TPC have crucial influences on the catalytic activity of the TPC. The catalyst with a longer spacer arm, which links the catalytic group to the matrix microspheres, has higher activity. The bonding density of QPS group on the polymer microspheres affects the hydrophilic and hydrophobic property of the TPC and, accordingly, affects the catalytic activity greatly. There is a maximum conversion of 1-bromobutane as the bonding density of QPS group on TPC is 0.94 mmol/g. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 677–686, 2011