Benzenes 1.4- divinylbenzene

Figure 3.23 Photographs of powders of mesoporous hybrid materials with various conjugated ir-electron systems (from left to right) ethene-, benzene-, 1,4-divinylbenzene-, 4,4 -divinylstilbene-, and 4,4 -divinylazobenzene-bridged organosilicas. (See color insert.)...

J. W. Kelly and J. T. Stewart, Separation of selected beta lactam antibiotic epimers on gamma cyclodextim ion exchange ethylvinyl benzene divinylbenzene copolymer and poly(styrene-divinyl benzene) copolymer stationary phases, J. Liquid Chromatogr., 14 2235(1991). 

Size-exclusion Molecular size Sulfonated divinyl benzene Divinylbenzene Silica gel Porous gel Aqueous gel Organic gel Controlled pore silica Controlled pore glass... 

Benzene, diethenyl- Benzene, divinyl- CCRIS 4809 Diethenylbenzene Divenylbenzene Divinyl benzene Divinylbenzene-65 Divinylbenzene, pure DVB-22 DVB-27 DVB-55 DVB-80 DVB-100 EINECS 215-325-5 HSDB 5449 NSC 4833 Vinylstyrene. Mixture of 0, m and p-isomers. Mixture of isome rs of divinylbenzene. 

A sulfuric acid-functionalized IL covalently supported on a polymer was successfully prepared for the esterification reactions [115], The catalyst was prepared by copolymerization of vinyl benzene, divinylbenzene, and vinyl chloromethyl benzene, followed by covalent attachment of imidazole group, reacted with 1,3-propane sultone, and then treated by sulfuric acid. Compared to the results when using free l-(3-sulfopropyl)-3-H-imidazolium hydrosulfate ([SOjH-PHImJpSOJ) as catalyst directly, those of the polymer-supported IL catalyst showed similar activity. For the esterification reaction of acetic acid and butanol, the yields to butyl acetate were... 

FIGURE 27 14 A section of polystyrene showing one of the benzene rings modified by chloromethylation Indi vidual polystyrene chains in the resin used in solid phase peptide synthesis are con nected to one another at various points (cross linked) by adding a small amount of p divinylbenzene to the styrene monomer The chloromethylation step is carried out under conditions such that only about 10% of the benzene rings bear —CH2CI groups... 

The coupling reaction of zinc(II) (3- or)8-monobromodeuteroporphyrin dimethyl ester (ID with 1,4-divinylbenzene under the typical conditions of the Heck reaction results in the formation of dimeric porphyrin 12 linked via a divinylbenzene moiety. Use of 1,3,5-trivinyl-benzene in the same reaction makes the trisadduct available."5... 

Other acylations using the copolymer l-acyl-4-vinylimidazole/divinylbenzene/ styrene (48 4 48) in solvents like 1,4-dioxane, benzene, diethylether, or acetone produce within reaction times of three hours the amide yields listed in Table 4-4.[122]... 

Figure 1. Role of dose rate in the synergistic effect of divinyl-benzene and sulfuric acid on grafting of styrene on polypropylene film in methanol dose rate of 4.1 x 104rad/hr to total dose of 2.4 x lO rad (A) styrene-methanol, (o) styrene-sulfuric acid (0.2M). ( ) styrene-methanol-divinylbenzene (1% v/v), and (o) styrene-methanol -di vinyl benzene (1% v/v)-sulfuric acid (0.2M). dose...

Zhang developed a monolithic poly(styrene-co-divinylbenzene) CEC column in which the EOF is supported by carboxyl groups of polymerized methacrylic acid [ 133]. Using benzene as a probe, column efficiencies of 90,000 -150,000 were observed within a flow velocity range of l-10cm/min (0.2-1.7 mm/s). Different families of compounds such as phenols, anilines, chlorobenzenes, phenylendi-amines, and alkylbenzenes were well separated typically in less than 5 min using 20 cm long columns. 

Note Normally inhibited with 8-12 ppm 4-7er7-butylcatechol to prevent polymerization. According to Chevron Phillips Company (March 2002), 99.93% styrene contains the following components (ppm) benzene (<1), toluene (<1), ethylbenzene (50), a-meth ylstyrene (175), m + p-xylene (120), o-xylene (125), isopropylbenzene (100), / -propylbenzene (60), m + p-ethyltoluene (20), vinyltoluene (10), phenylacetylene (50), m + p-divinylbenzene (<10), o-divinylbenzene (<5), aldehydes as benzaldehyde (15), and peroxides as benzoyl-peroxides (5). 

The corresponding catalytic version of this reaction was performed using either naphthalene- or biphenyl-supported polymers 594 or 595, respectively, which were prepared by cross-coupling copolymerization of 2-vinylnaphthalene or 4-vinylbiphenyl with vinyl-benzene and divinylbenzene promoted by AIBN in THF and polyvinyl alcohoP . These polymers have been used as catalysts (10%) in lithiation reactions involving either chlorinated functionalized compounds or dichlorinated materials in THF at —78°C and were re-used up to ten times without loss of activity, which is comparable to the use of the corresponding soluble arenes. 

Polystyrene is presently the overwhelming choice as the polymer support [Frechet and Farrall, 1977 Frechet et al., 1988 Messing, 1974]. The polystyrene used is a crosslinked polymer prepared by copolymerization of styrene with divinylbenzene (DVB). (The divinyl-benzene is usually the commercially available mixture containing the meta and para isomers... 

For the SPE of the more polar aromatic sulfonates, IPs with tetralkylammonium are previously formed [85,93,94]. The combination of the formation of IP with cetyltrimethylammonium and SPE is efficacious in the extraction of benzene and naphthalene sulfonates from an aqueous environment. Good recoveries are also obtained with octylammonium acetate as the IP agent, both when it is added to the aqueous sample prior to the extraction and when it saturates the solid phase to produce an anion-exchange column [95,96]. An alternative approach is based on the use of deactivated charcoal (Carbonpack B) [96] or of chemically modified polystyrene-divinylbenzene resins [85]. Often graphitized carbon black (GCB) is used for the clean-up process of the sample [96]. 

Because of its chemical inertness, no direct way of curing poly(thiocarbonyl fluoride) has been found. However, creep has been reduced and strength at elevated temperatures improved by milling into the polymer a free-radical generator, such as dicumyl peroxide or azobisisobutyronitrile, and a free-radical acceptor, such as N,N -m-phenylenebismaleimide or triacryloylhexahydro-s-triazine, and curing with heat and pressure (65). A better method is to mill in divinylbenzene and a small amount of benzoyl peroxide and cure with heat and pressure (66). The divinylbenzene forms a crosslinked matrix that mechanically traps poly(thio-carbonyl fluoride) molecules. Since the elastomer is in effect filled with poly(di-vinyl benzene), the final composition is less resilient than untreated poly(thio-carbonyl fluoride). 

Poly(4-vinylpyridine) resins 6 cross-linked with 9.6 % divinylbenzene and 68-82 % alkylated also have been tested as catalysts for reaction of 1-bromooctane with cyanide ion 81). The catalytic activities depended on the organic solvent in the order benzene > toluene > o-dichlorobenzene. No swelling data were reported, so it is not known if the activities correlate with the swollen volumes of the catalysts. 

Polystyrene and its divinylbenzene cross-linked copolymer have been most widely exploited as the polymer support for anchoring metal complexes. A large variety of ligands containing N, P or S have been anchored on the polystyrene-divinylbenzene matrix either by the bromination-lithiation pathway or by direct interaction of the ligand with C1-, Br- or CN-methylated polystyrene-divinyl-benzene network [14] (Fig. 7). 

PCB ADSORPTION. PCBs are practically insoluble in water because of a very weak solute-water interaction PCBs will have a strong solute-polymer interaction if a polymer such as styrene-divinyl-benzene is used water will have a weak interaction with styrene-divinylbenzene thus, conditions for effective adsorption are present. Therefore, large volumes of water can be passed through a column packed with a styrene-divinylbenzene polymer, and the PCBs will be adsorbed (partitioned) efficiently. 

PCB DESORPTION. PCBs are very soluble in a number of organic solvents. Because acetone is very effective in displacing the water from the pores of the polymer, it will be used in this example of desorption. A fairly strong interaction of acetone with the styrene-divinylbenzene surface can be predicted because acetone and benzene are miscible solvents. Consequently, a small amount of acetone will desorb the PCBs because strong solvent-solute and solvent-polymer interactions override the strong solute-polymer interaction. This desorption, commonly called elution, does not occur during the adsorption process because the matrix water is a poor eluent dictated by its weak interaction with hydrophobic polymers. 

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