Styrene divinylbenzene copolymer beads

Hard, attrition-resistant, insoluble synthetic polymers (typically a copolymer of styrene with divinylbenzene). The resins are manufactured in a spherical bead shape that contain either exchangeable anion or cation portions, capable of exchanging with other anions or cations and usually in an aqueous medium. Typically cation resins for water softening will have a practical operating capacity of 20,000 gpg (at 6 lb NaCl per cu ft) rising to 30,000 gpg (at 15 lb NaCl per cu ft). 

The most frequently used organic supports are polystyrene and styrene-divinylbenzene copolymer beads with functional groups such as diphenylpho.sphine covalently bonded. The polymer-anchored catalyst complex can then be obtained, for example, by displacement of a ligand already co-ordinated to a soluble metal complex (Cornils and Herrmann, 1996) ... 

Hacroreticular resins are prepared by suspension polymerization of, for example, styrene-divinylbenzene copolymers in the presence of a substance which is a good solvent for the sononer but a poor swelling agent for the polymer [178-180]. Each resin bead is formed from many microbeads joined together during the polymerization process to create a network of holes and 7 channels. This results in greater mechanical stability,... 

New polymeric solid supports have been devised, which include macroporous styrene-divinylbenzene containing large fixed pores, porous glass beads, insoluble carbohydrate polymers, poly(ethylene oxide), cross-linked derivatives of polyacrylamide resins, and graft copolymers of polystyrene and poly(ethylene oxide). The last two have been the most effective and widely used and have competed well with the original copoly(styrene-divi-nylbenzene) beads. 

To a chilled (0°C) suspension of n-propylaminomcthyl poly(styrene)-1 % divinylbenzene copolymer beads (4.32 g, 0.522 mequiv N/ g resin, 2.25 mmol, 200-400 mesh), finely ground potassium carbonate (590 mg, 4.5 mmol), and DMF (50 mL) was added 3-bromo-5-hexyloxybenzenedia-zonium tetrafluoroborate (1.0 g, 2.69 mmol) in portions over 1 h (Scheme 13). After each addition, an aliquot of the DMF supernatant was diluted in diethylamine and analyzed by GC. Once diethyltriazene was detected, the additions were ceased and the suspension was transferred to a fritted filter using DMF and washed sequentially with 120 mL of the following solvents MeOH, water, MeOH, THF, and MeOH. The beads were then dried in vacuo to a constant mass to give 1 -(3-bromo-5-hexyloxyphenyl)-3-propyl-3-(ben-zyl supported) triazene as light yellow material. 

SEC stationary phases are usually composed of reticulated organic polymers (styrene-divinylbenzene copolymers) or minerals (hydroxylated silica) that are used as beads with diameters of 5 10 pm. Pore diameters, which can be varied during fabrication, are within the 4- 500 nm range. These materials, often called gels, must withstand the pressure drop across the column and temperatures in the order of 100 °C in order to allow their utilisation under various conditions. Standard columns have a length of approximately 30 cm (ID = 7.2 mm). 

Sulfonation of 8% Crosslinked Styrene Divinylbenzene Copolymer Beads... 

The above mentioned polymer-supported oxazaborolidines are prepared from polymeric amino alcohols and borane. Another preparation of polymer-supported oxazaborolidines is based on the reaction of polymeric boronic acid with chiral amino alcohol. This type of polymer can be prepared only by chemical modification. Lithiation of the polymeric bromide then successive treatment with trimethyl borate and hydrochloric acid furnished polymer beads containing arylboronic acid residues 31. Treatment of this polymer with (li ,2S)-(-)-norephedrine and removal of the water produced gave the polymer-supported oxazaborolidine 32 (Eq. 14) [41 3]. If a,a-diphenyl-2-pyrrolidinemetha-nol was used instead of norephedrine the oxazaborolidine polymer 33 was obtained. The 2-vinylthiophene-styrene-divinylbenzene copolymer, 34, has been used as an alternative to the polystyrene support, because the thiophene moiety is easily lithiated with n-butyl-lithium and can be further functionalized. The oxazaborolidinone polymer 37 was then obtained as shown in Sch. 2. Enantioselectivities obtained by use of these polymeric oxazaborolidines were similar to those obtained by use of the low-molecular-weight counterpart in solution. For instance, acetophenone was reduced enantioselectively to 1-phe-nylethanol with 98 % ee in the presence of 0.6 equiv. polymer 33. Partial elimination of... 

In the ion exchange process the leach liquor is passed through a bed of anion exchange resin beads which are loaded with chloride or in some cases nitrate. The resin will normally be a polymer carrying quaternary amine functions and having the generalized formula Pol(NR3)x+Cl, where Pol represents a polymer chain such as styrene-divinylbenzene copolymer, R = alkyl and... 

Pepper [22] proposed that the sulfonation of neutral poly(styrene-divinylbenzene) copolymer beads proceeded in a layer-by-layer fashion and could be stopped at any particular depth, giving a partially sulfonated bead with a low capacity and a known depth of functionality. From this concept Pepper [23] prepared the first superficially sulfonated polymer beads. Parrish [24] also prepared surface-sulfonated beads and gave a brief example of their utility. 

The resins [1-11,54-57] are usually bead-like styrene-divinylbenzene (DVB) copolymers, containing 2-8% DVB, which is equivalent to X2-X8 crosslinking of the network. Pearl or ground (meth)acrylate-divinylbenzene or (meth)acrylate-ethyl-ene dimethacrylate copolymers are also used. The most usual products of these types... 

The porogen is usually an inert solvent, or mixtures of inert solvent and polymers. The meso- and macropores in the polymer network are the voids once occupied by the porogen. Individual recipes for the preparation of macroporous polymer beads may seem complex in terms of the number of components involved and the required control of the experimental conditions. The technology, however, for their preparation has been developed to such a degree that excellent control over their properties (e.g. particle size, shape, porosity and chemistry) is routinely achieved. The vast majority of current macroporous polymers are based on styrene-divinylbenzene copolymers. Other suitable monomers include acrylates, methacrylates, hydroxyalkylacrylates, vinylpyridines and vinyl acetate. A wide range of products are available for HPLC in particle sizes from 5-20 p,m, pore diameters from about 2-400 nm, and surface areas from about 50-500 m /g [141,144,146-148]. 

The most commonly used polymeric support is a copolymer styrene/divinylbenzene functionalized with various reactive groups such as chloromethyl (Merrifield resin) and various spacers such as ethylene glycol (Wang-type resin). The supports now available vary one from another in many aspects and properties functionalization, cross-linking, porosity, loading, bead size. All these variations generate different swelling behaviours, different hydrophilicity, and different chemical stability. 

Preparation of Chromatographic Supports. Styrene-divinylbenzene copolymers (Bio-Beads SX2, 200-400 mesh) from BioRad, France, were first chlorosulfonated (17). Further reaction of the chloro-... 

Microporous beads are weakly crosslinked resins obtained by suspension polymerisation of styrene and divinylbenzene in the absence of any porogen agent. This process leads to the formation of a homogeneous network evidenced by a glassy and transparent appearance. The most commonly used supports for solid-phase organic synthesis and catalysis are styrene-divinylbenzene copolymers crosslinked with only 1-2% DVB. Many of their derivatives are commercially available [20]. 

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