The physicochemical properties of polymers are mainly dependent on the nature of polymer backbone and/or pendant groups linked to the main chain. Therefore, synthetic modification of these functional groups via post functionalization is an important approach for obtaining novel polymeric systems with improved properties and targeted applications. In this context, the synthetic modifications of nitrile group in polymers into various useful functionalities have received considerable attention and several interesting applications of the resulting polymers have been identified. The majority of the studies are based on Polyacrylonitrile (PAN), and some isolated examples of nitrile functionalization in copolymers such as Poly (Styrene-co-Acrylonitrile) (SAN), Poly (Acrylonitrile-co-Butadiene-co-Styrene (ABS) and Nitrile Rubber (NBR) are available. These synthetic modifications are mainly accomplished by the reactions such as Nucleophilic addition, cycloaddition, reduction, and hydrolysis using various reagents. These studies describing the post-polymerization modifications of nitrile group in polymers reported during the last three decades are covered in this review.
Concise and efficient methods for the syntheses of functionalized Indene and Indanone derivatives from Morita-Baylis Hillman (MBH) alcohols via Palladium catalyzed annulations are described. The formation and nature of the product was based on the MBH adduct used and the reaction conditions established after detailed optimization studies. The reaction of Baylis-Hillman alcohols (1 a-m) in presence of Pd(OAc) 2 (5 mol %), P(o-Tol) 3 (20 mol %) , AgOAc (1 eq.) and Na 2 CO 3 (2 eq.) in Dioxane at 120°C under Nitrogen atmosphere provided substituted indenes (2 a-m) in good to excellent yields. While, Indanone derivatives (4 a-f) are obtained from o-halo substituted MBH adducts (3 a-l) when subjected to reaction with Pd (OAc) 2 (3 mol %) and K 3 PO 4 (2.5 eq.) in DMA at 140°C in the absence of any ligand or additive.
Development of a novel, greener and efficient heterogeneous catalytic system for copper free Sonogashira reaction in water is described. This novel catalyst can be easily prepared by a simple method through synthetic modification of nitrile group in Polyacrylonitrile (PAN) using monoethanolamine (MEA) followed by its complexation with palladium chloride (PdCl2). The resulting polymer Pd complex (mPAN‐Pd) was characterized by means of Fourier Transform Infrared Spectroscopy (FTIR), Energy‐Dispersive X‐ray Spectroscopy (EDAX), Inductively Coupled Mass Spectrometry (ICP‐MS) and X‐ray Photo Electron Spectroscopy (XPS) analyses. mPAN‐Pd was then explored as highly efficient heterogeneous catalyst for Sonogashira coupling reaction under copper and ligand free conditions in water affording the corresponding coupling products up to 97 % isolated yield. Moreover, the catalyst was recovered by simple filtration after the reaction and reused for next 5 cycles with excellent stability and activity. This is the first report on the use of ethanolamine modified PAN Pd (II) complex as an efficient heterogeneous catalyst for a coupling reaction.
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