Effect of polymer architecture on the efficiency of acyl transfer reactions

Abstract

A series of spacer-modified polystyrene-supported hydroxamic esters and hydroxamic dithiocarbonic anhydrides were prepared starting from divinyl benzene and ethyleneglycol dimethacrylate crosslinked polystyrene resins through multistage polymer-analogous reactions. Acyl transfer reactions using these polymer-supported hydroxamic acylating agents containing spacer arms of various lengths were carried out. The investigation revealed a sharp increase in reactivity as the length of the spacer arm was increased from zero methylene spacer to five methylene spacers. Investigations were also carried out to correlate the extent of acyl transfer with the nature and degree of crosslinking and the relative polarity of the polymer network. It was found that the extent of functionalization in each of the polymer analogous reactions and the extent of acylation reaction decreased with an increase in the degree of crosslinking.

Regio-Selective Formation ofO-Acyl/O-Benzoyl Hydroxamates by Using a Polymer Supported Reagent Strategy

“…Recently polymer bound nucleophiles (anions) have been employed for a number of organic conversions [5][6][7] like alkylation, arylation, sulphonation, oxidation, aldol condensation and thiocyanation. Recently polymer bound nucleophiles (anions) have been employed for a number of organic conversions [5][6][7] like alkylation, arylation, sulphonation, oxidation, aldol condensation and thiocyanation.…”

Polystyrene-supported hydroxamic dithiocarbonic anhydrides: A new class of acyl transfer reagents

“…Investigations with various polymeric reagents have revealed that nature of the polymeric backbone does influence the kinetics and extent of functional group conversion in polymer-aided reactions (Morawetz 1978(Morawetz , 1985. The binding of a functional group to a polymer chain generally results in a new reagent with different structure, reactivity and selectivity (George and Pillai 1988;Sreekumar and Pillai 1989;Sudhakaran and Pillai 1990;Sophiamma and Sreekumar 1997).…”

New polymer bearing hydroxamic acid chelating resin for binding of heavy metal ions

“…1,2 The poly(hydroxamic acid) resin has potential commercial importance with the knowledge that hydroxamic groups are able to form complexes with wide range of metal ions. [3][4][5] Such a resin can be used for the recovery of heavy metals from aqueous media and uranium extraction from seawater. 6,7 A characteric feature of the chelating resins is the preservation of their high selectivity with respect to individual ions in the presence of large quantities of other ions.…”