Resins prepared with divinylbenzene

The first example for Method 2 was reported by Nishide and co-workers, who polymerised a metal complex of 1-vinylimidazole with l-vinyl-2-pyrollidone and divinylbenzene [8]. The metal-vinylimidazole complex was copolymerised, cross-linked with l-vinyl-2-pyrollidone by y-ray irradiation and the template metal ion was removed by treating the polymer complex with an acid. These poly(vinyl-imidazole) (PVI) resins adsorbed metal ions more effectively than the PVI resin prepared without the template. The number of adsorption sites and the stability constant of the Ni(II) complex were larger for the PVI resin prepared with the Ni(II) template, as seen by the smaller dissociation rate constant of Ni(II) from the resin. 

One of the requirements of this approach is that the analytes must be stable at the boiling point of the solvent, since the analytes collect in the flask. The solvent must show high solubility for the analyte and none for the sample matrix. Since this is one of the oldest methods of sample preparation, there are hundreds of published methods for all kinds of analytes in as many matrices. For example, XAD-2 resin (sty-rene-divinylbenzene) that was used to collect air samples to monitor current usage of pesticides in Iowa was Soxhlet-extracted for 24 h with hexane/acetone [22], This is common in environmental sample analysis, and one will see rows and rows of these systems in environmental laboratories. One disadvantage of Soxhlet extraction is the amount of solvent consumed, though modern approaches to solid sample extraction have tried to reduce the amount of solvent used. 

The solid supports used in this study were macroporous co-polymers of vinylpyridine and styrene crosslinked with divinylbenzene. Polymers of this type in the form of beads are available commercially (e.g. Reillex 425) and were also prepared for this study by Purolite. For spectroscopic studies, a more convenient sample morphology was required and thin-film polymers of similar stoichiometry were synthesised by the group of Sherrington at the University of Strathclyde. Full details of the methods used to prepare thin film polymers are reported elsewhere.11 To generate the ion exchange resin, the pyridyl functionalities of the polymer were quatemised with methyl iodide (Eq 1). 

Polacrilin resin (Amberlite IRP-64) is prepared by the copolymerization of methacrylic acid with divinylbenzene (DVB). Polacrilin potassium (Amberlite IRP-88) is then produced by neutralizing this resin with potassium hydroxide. 

Related anchored l,l,3,3-tetraphenyl-2-oxa-l,3-diphospholanium bis-triflate (39) has been prepared by reaction of brominated poly(styrene-co-divinylbenzene) resin 38 with the phosphorous anion generated from l,2-bis(diphenylphosphino)ethane and sodium naphthalenide followed by further oxidation and reaction with triflic anhydride (Scheme 7.13) [55]. This supported reagent has also been employed, to a lesser extent than 37, for the formation of esters and amides by reaction of carboxylic acids with primary alcohols and amines, respectively. 

M. Negre, M. Bartholin and A. Guyot, Autocross-linked isoporous polystyrene resins, Angew. Makromol. Chem., 1979, 80, 19-30 J. Hradil and E. Kralova, Styrene-divinylbenzene copolymers post-cross-linked with tetrachloromethane, Polym., 1998, 39, 6041-6048 S. Belfer and R. Glozman, Anion exchange resins prepared from polystyrene cross-linked via a Friedel-Craft reaction, J. Appl. Polym. Sci., 1979, 24, 2147-2157. 

The term IPN was first used in 1960 to describe the apparently homogeneous product obtained from styrene crosslinked with divinylbenzene. IPNs were prepared from this system by taking a crosslinked poly(styrene) network and allowing it to absorb a controlled amount of styrene and a 50% divinylbenzene-toluene solution containing initiator. Polymerisation of this latter component led to the formation of an IPN, the density of which was greater than that of the original polymer. These materials were used as models for ion-exchange resins. 

Corn oil-based polymer resin, prepared by the cationic polymerisation of conjugated corn oil, styrene and divinylbenzene, using boron trifluoride diethyl etherate modifled by Norway fish oil as the initiator with 4-vinylbenzyl triethylammonium cation modified montmorillonite clay (VMMT) nanocomposites were reported. The resultant nanocomposites with 2-3 wt% VMMT exhibited significant around two-fold improvements in tensile modulus, tensile strength and toughness when compared to the pristine polymer. There is an improvement in thermal stability up to 400°C in the nanocomposites. ... 

The physical properties of the resin vary in a regular way with the amount of divinylbenzene used in its preparation. There has therefore been a tendency to equate the percentage of divinylbenzene used in the preparation with the amount of cross-linking in the copolymer. This may not be a valid assumption in all cases, and the cross-linking numbers afford only an indication of the extent of cross-linking. 

In order to prepare the strong- or weak-base anion-exchange resins, the styrene-divinylbenzene copolymers are reacted with chloromethyl methyl ether, which converts the phenyl residues into benzyl chloride groups that are subsequently allowed to react with either secondary or tertiary amines. The chloromethyl groups supposedly become attached to the 4-position in the phenyl residues. Trimethylamine (Dowex-1, Amberlite IRA 400) and di-methylethanolamine (Dowex-2, Amberlite 410) are typical of the tertiary amines used in the preparation of commercial resins. The quaternary ammonium ion-exchange resins are highly ionized and can be used over the entire pYl range (14). 

These polymers constitute the largest group to be discussed in this report and this is mainly because polystyrene and poly(chloromethylstyrene), often crosslinked with divinylbenzene, continue to be widely used in the preparation of functional polymers and resin-supported reagents. In fact most of the examples given here refer to the preparation of functional polymers rather than to new materials. This is a rapidly growing area of polymer chemistry and it is not possible to refer, in a compressed review of this nature, to all reports of functionalized styrene-based resins that have appeared in the past two years. This section falls naturally into three parts the first deals with styrene polymers and copolymers, the second with reactions on chloromethylated polystyrenes, and the third deals with styrene-related polymers. 

In addition to these four sorbent types, other bonded phases (e.g., sulfonyl-propyl, diethylaminopropyl, N-propylethylaminediamine), polymers (styrene divinylbenzene, polyvinylpyrrolidine), chelating resins, and specialty phases for specific compounds, such as columns for analyzing drugs of abuse in urine, pesticides according to standard EPA methods, or aldehydes and ketones from air, are commercially available. Reversed-phase sorbents have been prepared with different chemistries to provide unique selectivities—for example, light-loaded, non-endcapped Cig, monofunctional or trifunctional C g, and polar, non-end-capped Cg. 

Since the introduction of solid-phase peptide synthesis by Merrifield (1) nearly forty years ago, solid-phase techniques have been applied to the construction of a variety of biopolymers and extended into the field of small molecule synthesis. The last decade has seen the emergenee of solid-phase synthesis as the leading technique in the development and production of combinatorial libraries of diverse compounds of varying sizes and properties. Combinatorial libraries can be classified as biopolymer based (e.g., peptides, peptidomimetics, polyureas, and others [2,3]) or small moleeule based (e.g., heterocycles [4], natural product derivatives [5], and inorganie eomplexes [6,7]). Libraries synthesized by solid-phase techniques mainly use polystyrene-divinylbenzene (PS) derived solid supports. Owing to physieal and ehemical limitations of PS-derived resins, other resins have been developed (8,9). Most of these resins are prepared from PS by functionalizing the resin beads with oligomers to improve solvent compatibility and physical stability (8,9). 

In another procedure, the preparation of the polymer-supported scandium catalyst was performed according to Scheme 8.17 [70], Polystyrene, cross-linked with divinylbenzene, was treated with 5-phenylvaleryl chloride in carbon disulfide in the presence of aluminum trichloride. The carbonyl groups were then reduced using aluminum trichloride-lithium aluminum hydride in diethyl ether to afford double spacer resin. After sulfonation (chlorosulfonic acid/acetic acid), resin was treated with scandium(III) chloride in acetonitrile at room temperature to give the polymer-supported scandium chloride. Finally, it was treated with trifluo-romethanesulfonic acid to afford the immobilized triflate. 

In related work, Kingston and colleagues immobilized deacetylpaclitaxel 187 onto polystyrene (PS)-divinylbenzene (DVB) resin functionalized with a diethylsilyl linker to give 188 (Scheme 3.35) and used it to prepare paclitaxel analogs. Resin 188 was acylated once or twice to provide libraries of acyl- 189 or diacyl-analogs 191, which were cleaved from the resin under acidic conditions. ° ... 

Cationics. XAD resin has been successfully used for concentration of cationics from water (55). Kawabata and coworkers have found that a specially prepared resin material of poly(hydroxystyrene) highly crosslinked with divinylbenzene is a superior adsorbent for cationic surfactants (67). The mechanism appears to be acid-base reaction rather than ion exchange, since inorganic cations are not adsorbed. The cationic is recovered and the resin regenerated by elution with methanol. The capacity of this resin for cationics is higher than that of Amberlite XAD resins as well as traditional cationic exchange resins. The presence of salts or alkali in the matrix increases the capacity. 

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