Synthesis of a cellulose‐grafted polymeric support and its application in the reductions of some carbonyl compounds

Abstract

The reduction of carbonyl compounds by borohydride supported on a cellulose-anion exchange resin is known. The synthesis of a graft copolymer of cellulose and poly(4-vinyl pyridine) [CellO-g-poly(4-VP)] has been carried out with ceric ions as a redox initiator. A postgrafting treatment of CellO-g-poly(4-VP) with sodium borohydride has produced CellO-g-poly(4-VP) borane, a polymer-supported reducing agent. Optimum conditions pertaining to the maximum percentage of grafting have been evaluated as a function of the concentrations of the initiator, monomer, and nitric acid, amount of water, time, and temperature. The maximum percentage of grafting (585%) has been obtained with 0.927 mol/L of 4-vinyl pyridine and 0.018 mol/L of ceric ammonium nitrate in 120 min at 458C. The polymeric support, CellO-g-poly (4-VP) borane, has been used for reduction reactions of different carbonyl compounds such as benzaldehyde, cyclohexanone, crotonaldehyde, acetone, and furfural. The graft copolymer has been characterized with IR and thermogravimetric analysis. The grafted cellulose has been found to be thermally stable. The reduced products have been characterized with IR and NMR spectral methods. The reagent has been reused for the reduction of a fresh carbonyl compound, and it has been observed that the polymeric reagent reduces the compounds successfully but with a little lower product yield.

Photo‐induced graft copolymerization of acrylonitrile onto sodium salt of partially carboxymethylated guar gum

“…Below the optimum concentration the observed increase in the values of the grafting yields with increase in the nitric acid concentration is attributed to an increase in the initiation rate of photo‐grafting. However, at higher acid concentrations, the observed decrease in the percentage of grafting could be due to a corresponding reduction in ceric‐Na‐PCMGG complex formation as well as an increase in polymer termination rates …”

“…Therefore, the homopolymerization becomes the preferred process and decrease in %G and %GE is observed. Similar results are also reported in the literature …”

Synthesis, Characterization of Cellulose Grafted N-Oxide Reagent and Its Application in Oxidation of Alkyl/Aryl Halides

“…The details of the synthesis of 4-vinyl pyridine grafted cellulose has been discussed in our previous papers [24,25].…”

“…In the present work grafting onto cellulose is carried out in the presence of 4-VP, by chemical method using CAN as redox initiator. The detailed mechanism has been discussed elsewhere [24]. In general the mechanism of the transition metal ion induced grafting process, where glycol groups are involved, using Ce(IV) salt, can be represented as follows:…”

“…Therefore, it seems that in case of grafted pyridines, the presence of pendant reactive pyridyl group nitrogen on the repeating unit of polyvinyl pyridine will make the grafted polymer useful as a reagent. Recently we reported on the oxidation and reduction reactions using polymer supported reagents developed from cellulose grafted with 4-vinyl pyridine [24].…”