Polystyrene hydroxyethyl

The adaptation of the Bischler-Napieralski reaction to solid-phase synthesis has been described independently by two different groups. Meutermans reported the transformation of Merrifield resin-bound phenylalanine derivatives 32 to dihydroisoquinolines 33 in the presence of POCI3. The products 34 were liberated from the support using mixtures of HF/p-cresol. In contrast, Kunzer conducted solid-phase Bischler-Napieralski reactions on a 2-hydroxyethyl polystyrene support using the aromatic ring of the substrate 35 as a point of attachment to the resin. The cyclized products 36 were cleaved from the support by reaction with i-butylamine or n-pentylamine to afford 37. 

For (hydroxyethyl)polystyrene to succeed as a versatile synthetic intermediate (57), techniques must be evolved to replace oxygen by other atoms which may be more suited to good function of final reagent. Such conversions must be completely quantitative, since unreacted, side-reacted or over-reacted functionalities cannot be removed from the solid product, and may ultimately interfere with its destined activity. 

Chloroethyl)polystyrenes and (iodoethyl)polystyrenes are each prepared from the alcohol by common reagents in a single step without complications, but one-pot procedures fail to produce completely pure bromide, which must be prepared from the tosylate by assisted halide exchange (57). The preparation of (toluenesulfonyloxyethyl)polystyrene itself, if performed in ice-cold pyridine as for the free analogue (64, 65), required a week to complete (67) if quaternary ammonium and other side-products (68) are to be avoided. In contrast, with non-nucleophilic diisopropylamine (69) as acid acceptor instead of pyridine, (hydroxyethyl)polystyrene and toluene-sulfonyl chloride need only be refluxed in carbon tetrachloride for a few hours to give the desired tosic ester as sole product in quantitative yield (57). 

Transformations to polymer-bound amino compounds, which are often useful as ligands for metals ions or other free species (67), employ a wide selection of organic reactions. Quaternary ammonium salts result from heating isolated polymer tosylate with tertiary amine they may also be prepared in one step from (hydroxyethyl)polystyrene and toluenesulfonyl chloride and a two-fold excess of amine. 

Support-bound boranes have been prepared by hydroboration of vinyl polystyrene with 9-BBN, and used as intermediates for the preparation of hydroxyethyl polystyrene (Figure 4.5 [32]) and alkylated polystyrenes [33]. Hydroboration of vinyl poly-... 

Starting from L-tryptophan, immobilized on hydroxyethyl polystyrene through its carboxylic group, the intermediate a,[3-unsaturated imine (554) was formed by reaction with 3-methylcrotonaldehyde in pure trimethyl orthoformate (TMOF). The imine was then allowed to react with Fmoc chloride in the presence of pyridine to afford the required tetrahydro-[3-carboline (555) through an N-acylimin-ium ion mediated Pictet-Spengler-type cyclization. Further manipulation of the Pictet-Spengler product afforded the desired demethoxy-FTC as the minor cis isomer, along with its C-3 trans epimer (556) (diastereoisomeric ratio 1 3) (Scheme 115). 

Poly(styryl)lithium (> 15,000) In benzene solution was reacted with excess ethylene oxide In the presence of N,N,N, N -tetramethyl-ethylenedlamlne (TMEDA, [TMEDA]/[Li] 3.2). After 12 days at 25-30 C, size exclusion chromatographic analyses Indicated no significant ethylene oxide polymerization. Hydroxyethylated polystyrene was recovered in essentially quantitative yleU. 

Polymeric particles can be constructed from a number of different monomers or copolymer combinations. Some of the more common ones include polystyrene (traditional latex particles), poly(styrene/divinylbenzene) copolymers, poly(styrene/acrylate) copolymers, polymethylmethacrylate (PMMA), poly(hydroxyethyl methacrylate) (pHEMA), poly(vinyltoluene), poly(styrene/butadiene) copolymers, and poly(styrene/vinyltoluene) copolymers. In addition, by mixing into the polymerization reaction combinations of functional monomers, one can create reactive or functional groups on the particle surface for subsequent coupling to affinity ligands. One example of this is a poly(styrene/acrylate) copolymer particle, which creates carboxylate groups within the polymer structure, the number of which is dependent on the ratio of monomers used in the polymerization process. 

The classic studies of Saunders( 17) demonstrated that in the presence of excess surfactant methyl cellulose (MC) would desorb from monodispersed polystyrene latices. MC is one of the most surface active water-soluble polymers (W-SPs) and it will readily dominate the surface pressure 7T (7T = cre - cr t where cr is the surface tension of water and is the surface tension of the aqueous polymer solution) of the aqueous solution. For example, hydroxyethyl cellulose (HEC) lowers the surface tension of water much less than MC or HPMC, and when the combination of HEC and MC or HPMC in water is studied, there is no notable influence of HEC on the surface pressure (Figure 2). 

Similar increases in k with ultrasonic intensity have been found for other polymers such as polystyrene [44], poly(methyl methacrylate) [45], poly(dimethylsiloxane) [46], poly(ethyleneoxide), hydroxyethyl cellulose, poly(vinyl acetate), poly(acrylamide)... 

The % ring substitution of the polymer is a critical factor in catalytic activity. Its importance was demonstrated clearly in Regen s first full paper on triphase catalysis 89). Catalysts 2 and 13 (2% CL) were active for cyanide displacement on 1-bromooctane (Eq. (3)) only at 21 % or lower RS (Table 3). Commerical anion exchange resins, polystyrenes highly substituted as benzyltrimethylammonium ions 2 or benzyldimethyl-(2-hydroxyethyl)ammonium ions 14, were inactive. 

Resin-bound (4-acyloxy-2-buten-l-yl)silanes, which can be prepared from resin-bound allylsilanes and allyl esters by cross-metathesis, react with dilute TFA to yield free carboxylic acids (Figure 3.7 [75]). However, the scope of this strategy remains to be explored. Similarly, esters of polystyrene-bound (2-hydroxyethyl)silanes readily undergo acidolysis and have been used as acid-labile linkers (Figure 3.7 [76]). 

S47H10M43 82 Polystyrene-bfocfc-poly (2-hydroxyethyl methacrylate)- focfc-poly(methyl methacrylate)... 

Physical incorporation of different porphines (9) and also phthalocyanines (2) into polymer matrices were done by pearl polymerisations of glyddyl or 2-hydroxyethyl methacrylate and ethylene dimethacrylate -The amount of inorrporated dtielate is 0,05 to 0.4 wt %(50-70% of the inserted porphyrine). The surface hole is small enough to prevent diffusion of N4-chelates from the interior of the matrix. Also polymers, sudi as polystyrene or polyvinylalcohole, were directly used to incorporate porphyrines or phthalocyanines. ... 

Di-block copolymers may also be formed by using dithiocarbamate free radicals. Indeed, copoljoners containing poly(styrene) and poly(hydroxyethyl methacrylate) blocks have been obtained by a two-step procedure [145]. Firstly, styrene is photopolymerized in the presence of benzyl A,A-diethyldithiocarbamate (BDC) by a living radical mechanism [146]. In fact, as the benzyl and thiyl radicals, formed by the photoliagmentation of BDC, participate mainly in the initiation and termination reactions respectively, polystyrene with a dithiocarbamate end group is thus obtained. The successive UV irradiation of this polymer, in the presence of hydroxyethyl methacrylate (HEMA), gives rise to the di-block copolymer, according to Scheme 42. 

PS—polystyrene UF—urea-formaldehyde resin glut—glutaraldehyde thio— thiourea BSA—bovine serum albumin PHEMA—poly(hydroxyethyl methacrylate) IDA—iminodiacetic acid LDH—lactate dehydrogenase OPS—o-phosphoserine 8HQ—8-hydroxyquinoUne Bpa— bis(2-pyridyl-methyl) amine. 

Up to 1973 very little information had been published on these foams. France has produced polysulfone foams from expandable beads which resemble polystyrene beads in their processing. In a typical formulation 1- butene and sulfur dioxide are copolymerized in such a way that the copolymer contains excess unpolymerized 1-butene, which volatilizes to cause foaming. Water, ethyl hydroxyethyl cellulose, 1-butene, sulfur dioxide, and a solution of isoprophyl peroxydicaibonate in... 

The synthesis and purification of polystyrene methacryloyl macromonomers (PS-MA) in the molecular weight range Mn= 1000-2000 g mol 1 by living anionic polymerization of styrene (S), termination with ethylene oxide (EO), and subsequent reaction with methacrylic chloride has already been described in detail elsewhere [180] (see also Scheme 16). In this context it has to be emphasized that the hydroxyethyl-terminated PS-MA macromonomer precursor (PS-OH) as obtained after purification of the crude PS-OH by silica column chromatography (cyclohexane/dichloromethane 1/1 v/v) and as charged in the PS-MA synthesis still contains up to about 15 wt-% of non-functionalized polystyrene (PS-H). This PS-H impurity of the PS-MA macromonomer does not interfere with the PS-MA synthesis and the subsequent TBA/PS-MA copolymerization and is easily and conveniently removed from the resulting PTBA-g-PS graft copolymer (see below). 

Functional groups have also been placed on surfaces of organic colloidal particles prepared in an emulsion process. Vairon et al. applied ATRP to the homopolymerization of 2-hydroxyethyl acrylate (HEA) and 2-(methacryloyloxy)ethyl tri-methylammonium chloride from the surface of a crosslinked polystyrene latex functionalized with alkyl bromide groups. ATRP was carried out using the surface groups of the dialyzed latex as the initiators. The resulting hydrophobic core/hy-... 

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