A Modified Method for the Synthesis and Characterization of a Novel Surface-Enriched (with Active Site) Polymer-Supported Phase Transfer Catalyst Using Vinyltoluene as a Functionality and Its Catalytic Efficiency in Dichlorocarbene Addition to Olefines—A Kinetic Study

Abstract

A modified method with respect to an earlier conventional procedure was successfully attempted and we now report the new procedure for the synthesis of surface-grafting technique by the delayed addition of inexpensive vinyltoluene (VT) functionality to the partially polymerized supporting monomers viz., styrene (St) and divinylbenzene (DVB) via suspension polymerization. The resulting copolymer beads containing surface-enriched with methyl group were converted into a catalyst by chlorination followed by a quaternization process. Two groups (I and II) of SE-PSPTC beads were prepared by fixing the crosslinking amount (DVB) as 2% and 6%, respectively, 25% of VT as a common active site functionality and the rest of the contribution was styrene. Each group contains six different catalysts based on the concentration of active sites on the surface which in turn depends upon the partial polymerization time (PPT) of St/DVB i.e., 0, 3, 6, 9, 12, and 15 hrs. These two different groups and 6 different catalysts categories in each were prepared with the objective to learn the influence of higher/lower crosslinking in the process of surface-grafting of poly(VT) on poly(St/DVB) and to determine the optimized partial polymerization time to bring the maximum active site on the surface. The level of enrichment of an active site of all the catalysts were determined through [chloride], FT-IR, SEM, EDAX, and ESCA analyses. The gradual increase of [chloride], C-N peak intensity from FT-IR, rough surface/nodules concentration from SEM, % of surface chloride from EDAX, decreasing/increase trend of surface carbon/surface chloride in ESCA analyses starting with 0 VT to 15 VT irrespective groups, confirms the gradual increase of active site on the surface beads based on the PPT. The results of [chloride], spectral analyses and the rate constants of all the catalysts in dichlorocarbene addition to various olefines ensure that 9 VT-SE-PSPTC was the best catalyst beads in both the groups due to its two-fold enhancement rather than the conventional catalyst (0 VT) of both groups although we had added the same amount of VT in both preparations.

Keywords:

• Surface-grafting
• Partial polymerization
• Delayed addition
• Surface-enriched (with active site) polymer-supported phase transfer catalyst
• Semi-emprical
• Semi-quantitative

Acknowledgment

One of the authors, E.M. thanks to the University Grants Commission, New Delhi, Govt. of India, for financial assistance.