M. Hassanein

Autoxidation of 2,6-di-t-butylphenol catalyzed by cobalt (II) schiff-base complex bound to cationic latex

Abstract A cationic latex has been prepared by emulsion copolymerization of styrene and divinylbenzene with 2 mol% of quaternary ammonium ion surfactant monomer 2. The cationic latex-bound cobalt (II) complex of N , N ′-ethylenebis-(salicylaldimine-5-sodium sulphonate) 1 showed high catalytic activity in the autoxidation of 2,6-di-butylphenol in water compared with the conventional polymer-free system. Reaction product was identified as 2,6-di-t-butyl-1,4-benzoquinone and the oxidative coupling product 3,3′,5,5′-tetra-t-butyl-4,4′-diphenoquinone. Reaction rate has been found to increase with increase of the concentration of Schiff-base complex 1 and to decrease as the concentration of latex particles increases at constant concentration of 1. The rate dependence on pH and phenol concentration showed a maximum. Colloidal catalyst showed some loss of activity after successive runs.

Preparation of poly(vinylbenzyltriphenylphosphonium perbromide) and its application in the bromination of organic compounds

Insoluble poly(vinylbenzyltriphenylphosphonium perbromide) was prepared by the chemical modification of 2% crosslinked poly(p-bromomethylstyrene) with triphenylphosphine followed by treatment of the obtained polymeric salt with bromine. The activity of the resulting polymeric brominating reagent was compared with that of the low molecular weight model reagent in the direct brominations of alkenes and carbonyl compounds. In addition to the excellent yields of the brominated products and the ease and simplicity of the method, the resulting polymeric by-product could be simply regenerated to give the reagent without loss of activity.

Synthesis and chemical modification of poly(methyl methacrylate) resins

Abstract The synthesis by suspension polymerization of some beaded resins based on poly(methyl methacrylate) and their chemical modification are described. The polymer composition and polymerization conditions were adjusted to produce a wide range of structural characteristics desirable for various types of chemical applications. The prepared poly(methyl methacrylate) beads were functionalized with amine derivatives and reduced with LiAlH 4 under phase transfer conditions. Further modifications via reactions of the so-formed aminoethyl and hydroxymethyl pendant groups generated a variety of functionalized supports.

The three dimensional polymeric tris [trimethyltin (IV] hexacyano iron (III) complex as an effective oxidizing agent

Abstract The polymeric intercalated complex [(Me3Sn)3Fe(CN)6]∞ showed higher activity in oxidation of phenols than the low molecular mass K3[Fe(CN)6] complex.

Chemically modified poly(methyl methacrylate) resin-bound triphenyl-phosphonium bromide as halogen-carrier in the bromination of organic compounds

Abstract Insoluble polymer-bound triphenylphosphonium perbromide was prepared by chemical modification of poly(methyl methacrylate) resin. The polymeric reagent was used for the bromination of alkenes, carbonyl compounds and arenes under mild conditions. In addition to the excellent yields of the brominated products and the ease and simplicity of the method, the resulting polymeric by-product could be simply regenerated and re-used.

Preparation of poly(methyl methacrylate) based resins with bound chromium (VI) reagents and their use as oxidizing agents

Abstract Insoluble polymeric dichromate and chlorochromate reagents were prepared by modification of poly(methyl methacrylate-co-divinylbenzene) beads with ethylene diamine followed by treatment of the resulting resin with excess methyl iodide and subsequent reaction with aqueous chromium trioxide or chromium trioxide and benzyltriethylammonium chloride respectively. These polymeric reagents were found selectively to oxidize alcohols to the corresponding carbonyl compounds. In addition to easy work-up of the reaction mixture, the resulting polymeric by-product could be simply regenerated and re-used.

Preparation of poly(vinyl benzyltriphenylphosphonium dichromate) and its application as an oxidizing agent

Abstract Insoluble poly(vinyl benzyltriphenylphosphonium dichromate) reagent was prepared by chemical modification of 2% crosslinked polychloromethylstyrene with triphenylphosphine, followed by treatment of the obtained polymeric salt with chromium trioxide in water. The activity of the resulting polymeric dichromate reagent was compared with that of the low molecular weight model reagent in selective oxidation of alcohols to the corresponding carbonyl compounds. The polymeric reagent could be easily regenerated and re-used with little loss of activity.

Synthesis of poly(vinylbenzyltriphenylphosphonium)-bound nucleophilic reagents and their applications for anionic activation in nucleophilic substitutions

Abstract Insoluble polymer-bound nucleophilic reagents derived from poly(vinylbenzyltriphenylphosphonium chloride) have been prepared by treatment with the sodium salts of carboxylic acids, benzenesulphinic acid and phenols. These reagents were used for the synthesis of carboxylic acid esters, sulphones and C/O-alkylation of phenols by reactions with alkyl halides. In addition to the ease and simplicity of the method and regeneration of the polymeric by-product, the polymeric reagent seems to increase the nucleophilicity of the anions. The products were obtained in higher yields than those for the corresponding polymeric phase transfer catalyst which need long reaction time and gave no satisfactory yields especially in non-polar solvents.

Preparation and synthetic application of poly(4-vinylpyridine) based resins with bound nucleophilic reagents

Abstract Insoluble polymer-bound nucleophilic reagents were prepared by modification of crosslinked poly(4-vinylpyridine), poly(4-vinylpyridine-co-styrene) and poly(4-vinylpyridine-co-methyl methacrylate) with n-butyl bromide and subsequent reaction with the sodium salts of carboxylic acids and sodium-β-naphthoxide. These reagents were used for the preparation of carboxylic acid esters by their reactions with alkyl halide and alkylation of β-naphthoxide with benzyl chloride. The products were obtained in high yields and the polymer by-products could be regenerated and re-used with some loss of activity. The product distribution of C/O-alkylation of β-naphthoxide was found to be affected by the nature of the micro-environment.

Cationic polymer colloid for promotion of nucleophilic displacements in aqueous medium

Abstract A cationic latex I was prepared by emulsion polymerization of styrene, 50 mol.% of chloromethylstyrene, 1 mol.% of divinylbenzene, 2 mol.% of vinylbenzyltrimethylammonium chloride followed by treatment of the obtained polymer with trimethylamine. This colloidal polymer I showed good activity for promotion of the reaction of the sodium salts of carboxylic acids and alkyl halides in an aqueous medium. Good yields of esters were obtained and no coagulation of the latex was observed under the reaction conditions.