Polyvinylpyrrolidone-bromine complex: An efficient polymeric reagent for selective preparation of benzyl bromides in the presence of hexamethyldisilane

Benzylic bromides were conveniently obtained in high yields via the reaction of the corresponding alcohols with crosslinked polyvinylpyrrolidone-bromine complex (PVPP-Br2)/hexamethyldisilane in chloroform at reflux condition. Selective conversion of benzyl alcohol to benzyl bromide in the presence of primary aliphatic alcohols, e.g. 2-phenylethanol was also achieved. KEY WORDS: Polyvinylpyrrolidone-bromine, Benzyl bromide, Hexamethyldisilane, Selective bromination Bull. Chem. Soc. Ethiop. 2012, 26(2), 305-309.DOI: http://dx.doi.org/10.4314/bcse.v26i2.1

Sulfuric acid supported on silica gel: An efficient catalyst for silylation of hydroxyl groups with HMDS and their convenient deprotection under non-aqueous condition

1165-1167A mild and efficient silylation of alcohols and phenols with hexamethyl-disilazane(HMDS) and convenient desilylation of the corresponding silyl ethers are achieved using a catalytic amount of H2SO4/SiO2 under non-aqueous condition. In this work chemoselective silylation of hydroxy compounds in the presence of thiols and amines is conducted

Selective conversion of nitriles to amides by Amberlyst A-26 supported hydroperoxide

974-975A mild, efficient and selective conversion of nitriles to amides is achieved by employing Amberlyst A-26 supported hydroperoxide, which is prepared in situ from hydrogen peroxide and Amberlyst A-26 (OH- form). Nitriles and dinitriles are transformed to their corresponding amides and diamides, respectively. Reactions proceed within 0.5-5 hr upon addition of a catalytic amount of Amberlyst A 26(OH-) to a methanolic solution of nitrile and hydrogen peroxide (35%), at room temperature.</span

Oxidative coupling of thiols to disulfides by piperazinium dichromate

1293-1295Aliphatic and aromatic thiols are oxidized to the corresponding disulfides in the presence of piperazinium dichromate under mild condition

Synthesis, Characterization, and Properties of Sulfonated CNT‐Doped Poly(aniline‐co‐carbazole)‐PVA Conductive Films

Abstract Conductive flexible films are successfully synthesized from polyvinyl alcohol matrix and poly(aniline‐co‐carbazole) charge carrier. To improve the mechanical properties of polyvinyl alcohol and promote charge transition in the conductive copolymer, dual purpose sulfonated multiwall carbon nanotube is added. Conductivity is enhanced via sulfonic acid protonic dopant and mechanical property is increased by its hexagonal nanorods. Nanocomposites are prepared by adding 0.025, 0.050, and 0.075 g of carbon nanotube which is added at 1%, 3%, and 5% loads to the polymer matrix. Films are characterized by infrared, UV–vis, X‐ray diffraction, scanning electron microscopy, and thermogravimetric analysis. Conductivity is measured by the four‐probe technique and mechanical property is assessed through tensile tests and dynamic mechanic thermal analysis. A 5 × 10−6 S cm−1 conductivity and 116 MPa tensile strength are recorded for the conductive film with optimum dopant/nanocomposite loads. The electrochemical property and corrosion resistance are studied by cyclic voltammetry and Tafel curves, respectively. The conductive films show an increase in corrosion potential and a decrease in corrosion current referring to a reliable corrosion protection film. The water uptake and contact angle of the films are measured to be 157% and 80.1° respectively to confirm its required hydrophilic property