Catalytic Potential of a New Polymer-Anchored Multisite Phase Transfer Catalyst in the Dichlorocarbene Addition to Inden
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Catalytic Potential of a New Polymer-Anchored Multisite Phase Transfer Catalyst in the Dichlorocarbene Addition to Indene P. A. Vivekanand Æ T. Balakrishnan
Received: 25 January 2009 / Accepted: 6 May 2009 / Published online: 22 May 2009 Ó Springer Science+Business Media, LLC 2009
Abstract The popularity of triphase catalysis in industries is due to straightforward catalyst recovery from reaction mixture. In this work we report a facile preparation a new polymer-anchored multisite phase transfer catalyst viz., polymer-anchored-2-benzyl-2-phenyl-1,3-bis (triethylmethylene ammonium chloride) (PABPBTAC) using polystyrene-based cross-linked beads. In order to ascertain the catalytic efficiency of the new heterogeneous catalyst, we studied its catalytic activity in the conversion of indene into dichlorocyclopropyl indene using chloroform and sodium hydroxide. Comparative catalytic efficiency of the new polymer-anchored multisite phase transfer catalyst with polymer-supported single site onium salts revealed that the new heterogeneous phase transfer catalyst is highly active than others. Further, from the influence of variation of experimental parameters, such as [substrate], [catalyst], [NaOH], stirring speed and temperature on indene conversion was studied in detail. Keywords Polymer-anchored phase transfer catalyst Triphase catalysis Interfacial mechanism Catalytic activity
1 Introduction The field of catalysis is providing chemists with new and powerful tools for the efficient synthesis of complex organic molecules. Reaction involving immiscible reactants is carried out by applying a protic solvent in a severe P. A. Vivekanand (&) T. Balakrishnan Department of Physical Chemistry, University of Madras, Guindy Campus, Chennai 600 025, Tamil Nadu, India e-mail: [email protected]
reaction condition generally accompanied with some unfavorable side-reactions [1], which are highly polluting and industrially undesirable. To carry out reactions involving such reactants, the methodology of phase transfer catalysis (PTC) has been successfully employed ever since Jarouse [2] carried out a reported alkylation of active nitriles with aqueous sodium hydroxide using soluble phase transfer catalysts. One of the most vital procedural predicaments in the industrial application of soluble phase-transfer catalyst (PTC) applications, such as quaternary ammonium salts, is the need to separate the catalysts from the reaction mixture and its subsequent reuse or disposal. Hence, from industrial point of view, polymer-anchored catalyst is more desirable in order to simplify catalyst separation from the reaction mixture and its reuse thereby the need for complex chromatographic techniques can be avoided for product separation and isolation [3–8]. To circumvent the problem of separation of catalyst from the reaction mixture, for the first time Regen [9] reported anchoring the phase transfer catalysts to a polymer backbone and suggested the name ‘‘Triphase Catalysis’’. Quaternary onium salts, crown ethers and cryptands have all bee
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