P-Vinylbenzyl chloride

Benzyl halides are known to be efficient deactivators for living polystyrene like allyl halides. It can be expected, however, that the reaction of a styryl carbanion with p-vinylbenzyl chloride competes with a side reaction involving attack of the carbanion at the double bond of p-vinylbenzyl chloride (VBC) ... 

Styrene-type macromonomers were also prepared by reaction of living PtBuA and PMMA chains with p-vinylbenzyl chloride, iodide or bromide , 4-(chlorodimethyl-silyl)styrene and 4-(chlorodimethylsilyl)-a-methylstyrene , respectively. 

A number of polymers containing a heterocyclic group have been prepared using the Reissert alkylation sequence.92 94 Thus, for example, the reaction of the isoquinoline Reissert anion (26) with polyfvinylbenzyl chloride) and sodium hydride gave 36, which on hydrolysis with base gave 37.92,93 A similar condensation takes place with quinoline, phenanthridine, and benzo-[/Jquinoline Reissert compounds.94 The Reissert anion 26 has also been alkylated with a mixture of m- and p-vinylbenzyl chloride and the product polymerized to a polymer of type 37.93 Copolymerization has also been studied.93... 

Trying to completely avoid the technically unpleasant process of chloromethylation, Negre et al. [48, 49] prepared a linear styrene copolymer with p-vinylbenzyl chloride and then subjected the product to self-crosslinking. Alternatively to the earlier-mentioned crosslinking of linear polystyrene with MCDE, this procedure results in local inhomogeneity of crosslinks distribution, because of the uneven distribution of the two comonomers along the initial chain (the monomer reactivity ratios of vinylbenzyl chloride and styrene are 1.41 and 0.71, respectively). Nevertheless, vinylbenzyl chloride became a popular comonomer for styrene and DVB in the preparation of beaded hypercrosslinked products [50-52]. 

Poly(p-vinylbenzyl chloride) Effect of catalyst type on structure [66]... 

An interesting synthetic approach was introduced by Ito et al. [99], They covalently bound an azoinitiator, 4,4 -azobis(4-cyanovaleric acid) to trypsin. In the presence of the monomers, 3-carbamoyl-1 -(p-vinylbenzyl)pyridinium chloride, or a mixture of methacrylic acid and methyl methacrylate, trypsin-polymer conjugates were synthesized (Fig. 3) which were sensitive to external signals, i.e., redox sensitive and pH sensitive, respectively. 

To 1.07 g of poly(styrene vinylbenzyl chloride) copolymer in EMF was added respectively 51 mg RB for P-RB-51, 102 mg RB for P-RB-102, 152 mg RB for P-RB-152, 305 mg RB for P-RB-305, 450 mg RB for P-RB-450, 610 mg RB for P-RB-610 and 152 mg RB for P-RB-1520. The mixtures were stirred magnetically and heated (80°) for 24 hours. The reaction mixtures were then cooled to ambient temperature. All the polymers were precipitated by addition of an excess of distilled water. They were then purified by precipitating fran DMF solution by excess of methanol and washed continuously with methanol until the final filtrates were colorless. The polymers were dried in a vacuum. 

An elegant alternative to living polymerization for the preparation of block polymers is to use functionalized Grignard initiators. The polymerization of methyl methacrylate to isotactic (in toluene at — 78"C) or syndiotactic polymers (in THF at — llO C) can be initiated by o-, m-, and p-vinylbenzylmagnesium chloride. The polymers had a low polydispersity and contained one vinylbenzyl group at the chain end, by H-NMR. The poly(methylmethacrylate) macromers thus obtained were polymerized or copolymerized with styrene to give graft and block polymers of controlled architecture [50,51]. 

Most Grignard reagents are inert toward styrene (up to the temperature of spontaneous thermal polymerization). This is a significant difference from lithium alkyls, which are readily able to initiate styrenic monomers [123]. The only reported exception is p-vinylbenzyl magnesium chloride, which polymerized styrene in THF at O C, but not at — 78X [50,51]. Substitution at the puru-position of a phenyl ring may stabilize the benzyl anion, owing to the delocatlization of electrons, and favor ionic dissociation of... 

Disulfide Formation in Polystyrene Networks. Polymer-bound thiols were prepared by copolymerizations of bis -vinylbenzyl)disulfide with other divinyl monomers followed by diborane reduction (Scheme 5) (fiS). The initially formed thiols were juxtaposed for reoxidation to disulfides. Polymer-bound thiols were prepared also by copolymerization of p-vinylbentyl thiolacetate with divinyl monomers followed by hydrolysis (Scheme 6). llie latter thiols were distributed randomly throughout the polymer network. The copolymer reactivity ratios for p-vinylbenzyl thiolacetate and styrene are unknown, but should be similar to those of styrene (Mi) and p-vinyl-bentyl chloride (M2) ri = 0.6, r2 = 1.1 (fifi). Copolymeiizations with equal volumes of monomers and 1/1 acetonitrile/toluene product macroporous 40-48% DVB-cross-linked networks (651. 

Bria et al. synthesized a tetracationic cyclophane-aromatic crown ether-type side-chain poly[2]catenane 59 by employing click chemistry, via route iii (Scheme 17.18) [111]. First, the template-directed coupling reaction between bis(bipyridinium) salt 28 and the alkyne-substituted p-xylylene dibromide 55, in the presence of dinaphtho crown ether 54, afforded an alkyne-functionalized [2]catenane 56 [112], Substitution of the chloro group on styrene-vinylbenzyl chloride copolymer 57 (M = 3.7 kDa, M , = 6.3 kDa) with sodium azide gave the azide-functionalized polymer 58 [83,113-115]. By employing CuS04/ascorbic acid as catalyst [116-120], click chemistry between azide-functionaUzed polymer 58 and alkyne-functionalized [2]catenane 56 afforded the side-chain poly[2]catenane 59, the successful formation of which was confirmed with Fourier transform infrared (FTIR) and NMR analyses. Unfortunately, both of these techniques revealed that the reaction of the azide groups was incomplete, and the observation was ascribed to a Coulombic repulsion of the cyclophane units and steric hindrance caused by the bulky catenane units[121]. 

Recently Asami et al. improved the method of preparing (p-vinylbenzyl) polystyrene macromer by direct reaction of living polystyrene with p-vinyl-benzyl chloride, in the presence of tetrahydrofuran without using a capping agent. 

Materials. 4-vinylbenzyl chloride, 4-(dimethylamino)pyridine (DMAP), 2,2-bis(hydroxymethyl) prpionic acid (bisMPA), benzaldehyde dimethyl acetal, p-toluene sulfonic acid-monohydride ( TSAOH), and n-butyl lithium (2.5M) were purchased from Sigma-Aldrich. Benzylidene-2,2-bis(oxymethyl)propionic acid and its anhydride were prepared following a literature procedure (2SJ. Dichloromethane (DCM) was distilled under nitrogen from calcium hydride immediately prior to use. Tetrahydrofuran (THF) was distilled under nitrogen from sodium/benzophenone immediately prior to use. All other reagents were commercially obtained and used without further purification. 

An interesting approach to polymercaptans utilizes the mercaptide ion as a blocking group. Vinylbenzyl thioacetate (26) (IX) was prepared in 68.5% yield by treating vinylbenzyl chloride (Villa) (70 30 p to o-isomer) with potassium thioacetate. Basic hydrolysis of DC yielded... 

Double hydrophilic block copolymers, RB-3 and RB-4 have been prepared directly in aqueous media by using a dithioester-capped poly(4-styrene sulfate) or a dithioester-capped poly[(p-vinylbenzyl) trimethylammonium chloride] as the macrochain transfer agent in the successive RAFT polymerization of the second monomer [47]. The block copolymer, RB-5 was prepared using seeded emulsion polymerization via the RAFT mechanism. First, seeded particles consisting of PBA dormant chains were obtained by using active xanthate agent, [l-(0-ethylxanthyl)-ethyl]benzene, under bath and starved-feed... 

General. Aqueous solutions of hydrophilic monomers were emulsified in xylene using water-in-oil emulsifiers, and polymerized using oil-soluble initiators. Typical hydrophilic monomers were sodium p-vinylbenzene sulfonate, sodium vinylbenzyl sulfonate, 2-sulfoethyl acrylate, acrylic acid, acrylamide, vinylbenzyl-trimethylammonium chloride, and 2-aminoethyl methacrylate hydrochloride. Typical oil-soluble initiators were benzoyl and lauroyl peroxides. In some cases, water-soluble potassium persulfate was used, both separately and in mixtures with oil-soluble peroxides. Of the water-in-oil emulsifiers, one of the most effective was Span 60 (technical sorbitan monostearate. Atlas Chemical Industries, Inc.). 

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