Polystyrene‐supported polyoxyethylene bound potassium permanganate as a heterogeneous oxidizing agent

Oxidation behavior of a 2 mol % divinylbenzene (DVB)‐crosslinked polystyrene‐supported permanganate function was investigated toward low molecular weight primary and secondary alcohols and aldehydes. The permanganate function was attached to a polystyrene support through cyclic polyoxyethylene (POE) units immobilized on the support. Contrary to the oxidations catalyzed by low molecular weight permanganate reagents, the oxidation of primary alcohol terminated in the aldehyde stage. The secondary alcohols were converted to the respective ketone and aldehyde to acid. The effect of the variable parameters similar to solvent, temperature, and reagent to substrate ratio was followed. Nonpolar cyclohexane was found to be the best solvent for the present study. Also the reactivity increased with increasing temperature. The oxidizing reagent possesses a long shelf life and could be recycled several times without reduction of capacity and mechanical stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3708–3717, 2003     

Polystyrene supported pyrazolinium Cr(VI) reagents: preparation and use in synthetic organic chemistry

Divinylbenzene (DVB) and ethyleneglycol dimethacrylate (EGDMA) crosslinked polystyrenes (2%) were functionalized to generate pyrazolinium chromate, chlorochromate and pyrazole–CrO₃ complex functionalities. These were found to oxidize primary and secondary alcohols to the corresponding carbonyl compounds in high yields. The influence of solvent, temperature, catalyst and molar excess of the reagent in these oxidation reactions was investigated to find out the optimum conditions for effective oxidation reactions. EGDMA crosslinked polystyrene supported reagents showed higher reactivity in terms of functional group capacity and percentage yield. Also, chlorochromate reagent was found to be very efficient in oxidizing alcohols to carbonyl compounds. The spent polymeric reagent after the oxidation step can be easily removed by filtration and can be regenerated many times. © 1998 SCI.     

Heterogeneous kinetics of oxidation of alcohols: PTC techniques

2‐ethyl‐1‐hexanol, n‐heptanol, and n‐hexanol oxidation by potassium permanganate was carried out in a baffled stirred reactor under heterogeneous conditions using phase transfer techniques. Tricaprylylmethylammonium chloride (Aliquat 336) was employed as the phase transfer catalyst. Kinetics of the oxidation was investigated. The rate constants were determined by varying the concentration of the catalyst, the concentration of alcohols and temperature. The rate constants agree well with those obtained under homogeneous conditions for all the three alcohols. The variation in the values under heterogeneous conditions were found to be less than 6 %.     

Reactivity of t-butyl chromate resins with substituted α-phenylethanols: A kinetic study

Polystyrene and polyacenaphthylene supports were functionalized to generate a t-butyl chromate function and the resulting polymer-supported reagents were used for the oxidation of alcohols. They were found to oxidize primary and secondary alcohols to the corresponding carbonyl compounds in quantitative yields. Oxidation of differently substituted α-phenylethanols was attempted for this purpose and the kinetics of oxidation reactions was studied. The reaction was found to be first order with respect to the substrate, the reaction being carried out with an excess of the t-butyl chromate reagent. The rate of oxidation was also found to be dependent on the nature of the substrate, concentration of the reagent function, and the nature and concentration of the acid catalyst used. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 799–804, 1998     

Crosslinking and biodegradation of poly(butylene succinate) prepolymers containing itaconic or maleic acid units in the main chain

Poly(butylene succinate)‐based prepolymers containing itaconic acid units or maleic acid units in the main chain were synthesized through the condensation reaction of 1,4‐butanediol, succinic acid, and itaconic acid or maleic acid. The resulting prepolymers, with weight‐average molecular weights in the several thousands, were cured at 115°C with benzoyl peroxide to produce crosslinked polyesters that were insoluble in chloroform. Differential scanning calorimetry analysis revealed that the glass‐transition temperature rose with crosslinking and that the melting temperature and heat of melting decreased with crosslinking. These results implied that crosslinking was successfully carried out and that the crystallinity of the polymer decreased. The crosslinked polymer showed lower biodegradability in the biochemical oxygen demand assay with activated sludge but retained some biodegradability. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1473–1480, 2005     

Convenient synthesis of benzoate esters mediated by polymer supported benzoyl chloride

Use of polymeric reagents simplifies routine acylation of alcohols because it eliminates traditional purification. We describe the use of readily available crosslinked poly(N‐benzoyl‐4‐vinylpyridinium)chloride, [P₄VP] COPh, in the solution phase synthesis of esters from alcohols or phenols in the presence of K₂CO₃ in high yields and purity. The products can be obtained by filtration and evaporation of the solvent and the polymeric reagent can be regenerated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Indirect electrooxidation of crotyl and cinnamyl alcohol using a Ni(OH)2 electrode

The heterogeneous catalytic redox behaviour of the nickel oxyhydroxide electrode surface was investigated with and without crotyl and cinnamyl alcohols using cyclic voltammetry. A comparison of the cyclic voltammograms recorded in the absence and presence of these alcohols confirmed the catalytic oxidation of the alcohols by the surface Ni³⁺/Ni²⁺ redox system at the electrode surface. Preparative scale experiments were also carried out using Ni(OH)₂ electrodes of large surface area and the redox behaviour of the electrode was confirmed by the isolation of crotonic and cinnamic acids with high yield efficiency. The influence of molecular size on the catalytic oxidation process is examined.     

Solvent free oxidation of alcohols catalyzed by KMnO4 adsorbed on Kieselguhr

Efficient and selective oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones catalyzed by potassium permanganate supported on Kieselguhr reagent under solvent free conditions are reported.     

Design and applications of a solid-phase oxidizing reagent consisting of a crosslinked polystyrene matrix and a t-butyl hypochlorite function separated by a trimethylene spacer

A crosslinked polystyrene–supported solid-phase analogue of t-butyl hypochlorite containing a trimethylene spacer group between the polymer matrix and the t-butyl hypochlorite function was prepared and used as a recyclable oxidizing reagent for alcohols. The synthetic route to this new polymeric reagent involved a seven-step polymer-analogous reaction starting from styrene-divinyl benzene 2%-crosslinked polymer. A β-ketopropionic acid function was introduced into the polystyrene matrix by Friedel–Crafts reaction with succinic anhydride. The keto function in the resulting polymer (2) (capacity, 3.57 meq of COCH₂CH₂COOH/g) was converted to the methylene group by Clemmensen reduction using zinc amalgam and HCl. The carboxyl function in the product polymer (3) was converted to the acylmalonic ester function by malonic ester synthesis through the reaction of the polymeric acid chloride (4) with ethoxymagnesium diethylmalonate. The polymeric acyl malonic ester (5) was decarboxylated to yield the 2-oxopentyl polystyrene resin (6). This on Grignard reaction with methyl magnesium iodide followed by hydrolysis afforded the polystyrene derivative with the t-butyl alcohol function separated by three methylene groups (7) . The t-butyl alcohol resin (7) was converted to the corresponding hypochlorite resin (8) by reaction with sodium hypochlorite. The resin was found to have a capacity of 2.84 mmol Cl/g by iodometric analysis. The capacities of the resins 2–8 were determined from the weight changes in the corresponding conversions and verified by quantitative determination of the functional groups. This new hypochlorite was found to oxidize alcohols to carbonyl compounds in 85–98% yield. The oxidizing efficiency of this new reagent was found to be significantly greater than those of the reagents containing only one spacer and no spacer between the reagent function and the polymer support. The presence of a 3-methylene spacer also facilitated the hypochlorite formation step significantly.     

Polymer‐Supported Bisacetoxybromate(I) Anion –‐An Efficient Co‐Oxidant in the TEMPO‐Mediated Oxidation of Primary and Secondary Alcohols

A polymer‐bound reagent for the efficient oxidation of primary alcohols to aldehydes and secondary alcohols to ketones in the presence of a catalytic amount of 2,2,6,6‐tetramethyl‐1‐piperidinyloxyl (TEMPO) is described. The oxidation process is particular mild and allows one to prepare aldehydes with α‐chirality without racemization. This also includes the synthesis of α‐aminoaldehydes. In most cases, work‐up of this heavy metal‐free oxidation is achieved by simple filtration followed by removal of the solvent. Insight into the role of the bromate(I) anion in the oxidation process was gained from the TEMPO‐mediated oxidation of benzaldehyde in the presence of the hypochlorite anion loaded on an anion exchange resin.     

Kinetics of amide formation on 1,4‐butanediol dimethacrylate crosslinked polystyrene resin: A comparison with PS‐DVB resin

An efficient crosslinked polymer support was synthesized by introducing 1,4‐butanediol dimethacrylate crosslinker to a polystyrene network using aqueous suspension polymerization technique. The support was functionalized with aminomethyl groups using chloromethyl phthalimide. The kinetics of amide bond formation on 1,4‐butanediol dimethacrylate crosslinked polystyrene (PS‐BDODMA) polymer were carried out using the attachment of Rink amide linker as a model reaction. The efficiency of the support was tested and compared with Merrifield resin by following different steps involved in the synthesis of a 14‐residue model peptide, Lys‐Ile‐Asn‐Thr‐Asn‐Ala‐Ser‐Trp‐His‐Ala‐Asn‐Arg‐Thr‐Ala‐NH_2, under the same synthetic conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2897–2903, 2003     

Study of the coagulated structure and fiber strength with wet spinning of aliphatic polyketone with aqueous composite metal salt solutions

Poly(1‐oxotrimethylene) (ECO) was dissolved in aqueous calcium chloride (CaCl₂)/zinc chloride (ZnCl₂) composite metal salt solutions, and the solutions had phase‐separation temperatures greater than 0°C. A higher proportion of CaCl₂ with respect to ZnCl₂ increased the phase‐separation temperature of the ECO solutions. When wet spinning was carried out with a coagulation bath at 2°C, an ECO solution with a higher phase‐separation temperature tended to produce greater ECO fiber strength. Therefore, a higher phase‐separation temperature resulted in coagulated filaments with a denser and more homogeneous cross‐sectional structure. When the metal salt concentration of the coagulation bath was increased with an ECO solution with a phase‐separation temperature of 22°C and a coagulation‐bath temperature of 2°C, the strength of the ECO fibers tended to be lower. Although little difference was observed in the uniformity of the fiber cross sections, a higher metal salt concentration in the coagulation bath facilitated greater spherical growth of the coagulated particles. Large, spherical coagulated particles promoted defects during drawing and thus lowered the strength of the ECO fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1250–1258, 2005     

Effect of fullerenes on the structure and properties of linear and crosslinked polyesterurethane ureas

Small concentrations up to 10^?6 mol/cm³ of C₆₀ fullerenes influence on both the molecular and topological structures changing at synthesis and the related mechanical properties of linear (pseudonetworked) and crosslinked polyester urethane ureas (PEUU). A crosslinked PEUU was synthesized on the base of poly(oxypropylene) macrodiisocyanate (POPMDIC) and 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane (MOCA) with virtually an equimolar ratio of amine and isocyanate groups, but the linear polymer was obtained with twofold molar excess of amine groups. Fullerenes change the network density, the share of the physical branching junctions and molecular weight distribution (MWD) of the chain segments between the networking junctions. Additionally, molecular weight and the polydispersity index increase with C₆₀ concentration in the reaction blend. This evidences to a branching role of C₆₀ during their interaction with terminating amine groups. An influence of MWD of the chain segments between the networking junctions on tensile strength of the crosslinked and linear polymers was assumed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1431–1442, 2007     

Nitroxide polymer brushes as efficient and recoverable catalysts for the selective oxidation of primary alcohols to aldehydes

2,2,6,6‐Tetramethylpiperidinyloxyl (TEMPO)‐containing polymer brushes were grafted onto crosslinked polystyrene microspheres via surface‐initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) of 2,2,6,6‐tetramethyl‐4‐piperidyl methacrylate, followed by an oxidation process with 3‐chloroperoxybenzoic acid as oxidant. The synthesized nitroxide polymer brushes included homopolymer brushes, block copolymer brushes, and random copolymer brushes with various TEMPO contents and molecular weights. They were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. These nitroxide brushes bearing high TEMPO contents were used as recoverable catalysts for the hypochlorite and aerobic oxidation of primary alcohols to aldehydes. The effects of polymer brush structure on the catalytic properties were studied and discussed. The results showed that these nitroxide polymer brushes had excellent catalytic properties and good recycling performances. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44365.     

Pervaporation separation of 1,1,2‐trichloroethane–water mixture through crosslinked acrylate copolymer composite membranes

The separation of a chlorinated hydrocarbon from a dilute aqueous solution through a crosslinked acrylate copolymer–porous substrate composite membrane by pervaporation was investigated. Poly(n‐butyl acrylate‐co‐acrylic acid) and poly(n‐butyl acrylate‐co‐2‐hydroxyethyl acrylate) were synthesized and composite membranes were prepared, which were made from the crosslinked polymer and a porous substrate. Pervaporation measurement was carried out for a dilute aqueous solution of 1,1,2‐trichloroethane at 25°C and under a vacuum on the permeate side (below 10 mmHg). The separation factor, overall flux, 1,1,2‐trichloroethane concentration in the membrane, and the degree of swelling decreased with increase in the acrylic acid or 2‐hydroxyethyl acrylate content of the acrylate copolymer. The influence of the crosslinking agent content on the pervaporation performance was small, and the separation factor and the overall flux showed a convex curve. The structure of the crosslinking agent had no effect on the separation. The influence of the pore size of the substrate and the thickness of the polymer layer on the separation of 1,1,2‐trichloroethane was observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 983–994, 1999     

Zinc‐based catalyst for the ring‐opening polymerization of cyclic esters

A zinc‐based catalyst zinc bis[bis(trimethylsilyl)amide] was used for the polymerization of cyclic esters including L ‐lactide (L ‐LA) and 2‐methyl‐2‐carboxyl‐propylene carbonate (MBC). The polymerization of L ‐lactide in THF could be carried out successfully under mild conditions in very short time by using the zinc catalyst and alcohols as the initiators. Kinetic study in solution polymerization prooved the polymerization has high monomer conversion degree close to 100% and the molecular weight of the resulting polyester has linear increase with the increase of [M]₀ /[I] (molar ratio of monomer to initiator). Sequential polymerization of L ‐LA and MBC in THF also showed high MBC conversion of 94% with a narrow molecualr weight maintained, indicating a living nature of this polymerization. The zinc catalyst system has also been used for the L ‐LA bulk polymerization with a high monomer conversion. ¹³C NMR indicated the polymer possesses high regioregularity and the minor regioirregular component was owing to the D ‐LA in the monomer inserted into the polymer mainchain during the transesterifcation. Interaction between monomer and zinc catalyst has been found to be a key factor to sustain a homogenous solution during the initiating procedure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The Beneficial Effect of Manganese Dioxide on the Oxidation of Organic Compounds by Potassium Permanganate

Addition of MnO₂accelerates the oxidation of alkyl arenes, sulfides and allylic alcohols by potassium permanganate under solvent free and heterogeneous conditions.     

Prostaglandins and prostaglandin intermediates. XV. Synthesis of 4-Oxo Carboxylic Acids and γ-Lactones by oxidative cleavage of homoallyl and homopropargyl ketones or alcohols

A convenient method to convert homoallyl or homopropargyl ketones or alcohols into 4-oxo carboxylic acids or γ-lactones is the oxidative cleavage of the multiple bond with potassium permanganate in diluted sulfuric acid. This is exemplified by the preparation of intermediates for the synthesis of 8-methylprostaglandin C₂. The oxidation of the allylic compounds with permanganate is compared with the oxidative cleavage by ozone/hydrogen peroxide, ozone/chromic acid or sodium periodate/potassium permanganate.     

Selective oxidation of steroidal allylic alcohols using pyrazole and pyridinium chlorochoromate

Abastract This paper presents a modified method for the selective oxidation of allylic alchols. Pyrazole, when used with pyridinium chlorochromate, is a mild and useful reagent system for the rapid and selective oxidation of steroidal allylic alcohols to the corresponding α, β-unsaturated ketones. The reaction of each substrate was carried out by adding the oxidant to a dry methylene chloride solution containing pyrazole and an allylic alchol. This report is the first on the use of pyrazole to augment selective oxidation by a chronium (VI) reagent.     

Influence of the network on the interaction parameter in system EPDM vulcanizate–solvent

Swelling measurements in six organic solvents were carried out on samples of dicumyl peroxide crosslinked ethylene–propylene–diene (EPDM) having various crosslink densities. The Flory–Huggins interaction parameter χ was determined for EPDM vulcanizates 312 and 812 as well as their mixture 312/812 using the Flory–Rehner equation. The results show that the χ parameter for the crosslinked polymer is greater than for the uncrosslinked one and is a linear function of the crosslink density. The swelling behavior of the networks were also interpreted by the Flory–Erman theory using the structural factor F₄′ to characterize the network and its behavior during the swelling. The obtained χ values indicate that broadening of the molecular mass distribution, in the Gaussian region of distribution, mixture 312/812, increases interactions with solvents. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:991–999, 1997