Divinylbenzene, cross-linking reagent

N-(Hydroxymethyl)acrylamide (HMA, Tokyo Kasei Co.) was recrystallized from ethyl acetate. N,N-Dimethylacrylamide (DMA, Tokyo Kasei Co.) and styrene (St, Kashima Kagaku Yakuhin Co.) were distilled at 54°C/3.5 mmHg and 40°C/14.5 mmHg, respectively. In some copolymerizations cross-linking reagents were added to reduce the formation of water-soluble polymer. N -Methylenebisacrylamide (MBA, Nakarai Chemicals Co.) and N-allylacrylamide (AAA, Polysciences, Inc.) were used as received. Divinylbenzene (DVB, Tokyo Kasei Co.) was treated with 10 % sodium hydroxide and dried. Two kinds of initiators were used Potassium persulfate (KPS, Taisei Kagaku Co.) was recrystallized from water and azobis(isopropyl-... 

The stereoselectivity of cyclopropane ester formation could also be effected by using reagents supported on linear or cross-linked polymers. The most important effects were noted with chloromethylated polymers cross-linked with divinylbenzene. The role of hyperconjugation in determining the stereochemistry of nucleophilic cyclopropanation of electrophilic alkenes has been studied and predicted In terms of equation 57 the... 

Polymeric reagent. Chapman and Walker have prepared a polymeric form of diphenyldiazomethane from a polystyrene cross-linked with divinylbenzene as shown. 

Polymeric reagent. Hodge and Richardson have prepared a polymer-supported triphenylphosphine by bromination of a polystyrene cross-linked with divinylbenzene followed by reaction with lithium diphenylphosphide (4, 303). A similar reagent has been described by Regen and Lee. Polymeric material is available from Strem. 

Low cross-linked polystyrene resins (1% divinylbenzene) is probably the most popular solid support. These resins swell to 2-6 times their original volume depending on the solvent used. Swollen resin, after removal of solvent and without excessive drying, remains in a rubbery state and can be easily flattened for FTIR study in the transmission mode. The support-bound compound should be washed free of reagent and solvent. 

A typical example is the conversion of octanol to actyl chloride in the presence of a carbon tetrachloride-triphenylphosphine reagent. A large increase in rate is measured when polymeric triphenylphosphines replace the momomeric reagent. The effect is particularly noticeable when a cross-linked rather than a linear polymer is used (rate increases 25-fold)157. This phenomenon is attributed to the specific microenvironment of the poly-styrene-divinylbenzene based polymer. Polvmeric phosphines are also used in the conversion of carboxylic acids to acid halides158-165. 

CM has been reported to provide a synthetic tool for immobilization of reagents. Polymer-supported synthesis with an allylsilyl unit as a linker was developed. Divinylbenzene cross-linked allyldimethylsilylpolystyrene has been reported to undergo highly efficient ruthenium-catalyzed CM with functionalized terminal alkenes (Eq. 45) [78]. Products have been liberated by proto-desilylation with trifluoroacetic acid. 

Nucleoside Acyclic Phosphates. - 2.1.1 Mononucleoside Phosphate Derivatives. A preliminary study on a novel solid phase reagent (Scheme 1) for the capture phosphorylation of nucleosides has been described. The 1 % cross-linked divinylbenzene-polystyrene copolymer, containing cyanoethoxy iV,AT-diisop-ropyl phosphine was used for the selective phosphorylation of uridine to 5 -uridine monophosphate (UMP) in 67% yield. ... 

Most polymeric redox reagents have been developed on microporous polystyrene, typically cross-linked with 1% divinylbenzene. Few examples have been reported for macroporous polystyrene, silica or other supports such as high-loaded cross-linked polyethylene imine (Ultraresins). Some problems specific for redox reactions can also arise from the reactivity of the polymer support itself. In cross-linked polystyrene, for example, benzylic positions can be oxidized at elevated temperatures and thus can account for a competing reaction pathway [8], Further reactivities are found for other solid supports as well. 

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