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Cerium(IV) mediated grafting of polyacrylonitrile on to guar gum was studied. Grafting parameters were studied gravimetrically, as a function of temperature, initiator concentration and Guar to acrylonitrile ratio. Higher temperatures resulted in higher monomer conversion and homopolymer formation. Both monomer conversion and extent of grafting increased with increase in cerium ion concentration in the range studied (0.91-9.12 mmol/l). Similar results were obtained with increase in monomer to guar gum ratio from 1 to 5. Grafting with this initiator was found to be generally good with high grafting efficiencies and low homopolymer formation for most experiments. The copolymers obtained were subjected to alkaline hydrolysis to convert nitrile groups in to carboxylic acid groups and the water absorbency of the resulting anionic guar gum was studied. Materials with water absorption up to 300 g/g could be obtained from this study. FIGURE 2. IR spectra of (a) native guar gum, (b) PAN-g-guar gum (GR ¼ 312%) and (c) alkali hydrolyzed PAN-g-guar gum. 666 / Thimma et al.

In this study, the Suzuki–Miyaura cross‐coupling reaction of naphthyl triflate with indole boronic acids catalyzed by a recyclable polymer‐supported Pd–NHC complex catalyst is presented. The polymer‐supported catalyst can be reused several times retaining high activity for the transformation. The structures of all the synthesized compounds were established by elemental analysis and from their mass, 1H‐NMR, and 13C‐NMR spectra.

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