Chloromethylation polystyrene

Montanari and coworkers have been particularly active in this area. They have generally utilized crowns or cryptands having long arms attached to them. These lipophilic arms are typically terminated in a primary or secondary amino function which may serve as a nucleophile in the reaction with a chloromethylated polystyrene residue. 

Warshawsky and coworkers have recently reported the synthesis of a class of compounds which they call polymeric pseudocrown ethers . A chloromethylated polystyrene matrix is used here as in 6.6.2, but instead of adding a crown to the backbone, a strand of ethyleneoxy units is allowed to react at two different positions on the chain, thus forming a crown. Such systems must necessarily be statistical, and the possibility exists for forming interchain bridges as well as intrachain species. Nevertheless, polymers which could be successfully characterized in a variety of ways were formed. A schematic representation of such structures is illustrated below as compound 30. ... 

A polymer-bound analog of the p-sulfonato-calix[6]arenes is described in a Shinkai patent [31,32], which states that the hexakis(carbetoxymethyl)ether of p-sulfonatocalix[6]arene was partially nitrated, ami-nated, and fixed on crosslinked chloromethylated polystyrene. This resin is stated to absorb 108 ixg of uranium... 

Recently, Deligoz and Yilmaz [51] prepared three polymeric calix[4]arenes, which were synthesized by reacting chloromethylated polystyrene with 25,26,27-tribenzoyloxy-28-hydroxy calix[4]arene (2a, 3a) and po-lyacryloyl chloride with 25,26,27,28-tetraacetoxy ca-lix[4]arene (4a). After alkaline hydrolysis of the polymers, they were utilized for selective extraction of transition metal cations from aqueous phase to organic phase. 

To support a polystyrene onto the upper rim of ca-lix[4]arene (phenolic-O- of calix[4]arene) and 25,26,27-tribenzoyloxy-28-hydroxy, calix[4]arene was treated with chloromethylated polystyrene in the presence of K2CO3 (Scheme 7). Polymeric calix[4]arene (3a) thus obtained was hydrolyzed in the benzoyl groups prior to use for the extraction process. 

The chloromethylated polystyrene resin used for Merrifteld solid-phase peptide synthesis is prepared by treatment of polystyrene with chloromethyl methyl ether and a Lewis acid catalyst. Propose a mechanism for the reaction. 

Grafting of 2-methyloxazoline onto chloromethylated polystyrene beads in benzonitrile at 110 °C gave graft copolymers, which were hydrolyzed to poly(styrene-g-ethylenimine) and useful as a chelating resin370. ... 

The immobilization of metal catalysts onto sohd supports has become an important research area, as catalyst recovery, recycling as well as product separation is easier under heterogeneous conditions. In this respect, the iron complex of the Schiff base HPPn 15 (HPPn = iVA -bis(o-hydroxyacetophenone) propylene diamine) was supported onto cross-linked chloromethylated polystyrene beads. Interestingly, the supported catalyst showed higher catalytic activity than the free metal complex (Scheme 8) [50, 51]. In terms of chemical stability, particularly with... 

Benzylic quaternary phosphonium and ammonium salts are dealky-lated by mild heating and/or nucleophilic anions, particularly iodide (9) and thiolate (10), but also hydroxide (11). Most N-benzyl-pyridinium or quaternary aryl ammonium compounds are particularly susceptible (12). Decompositions of this sort have seriously limited the usefulness of solid phase-transfer catalysts derived from (chloromethyl)polystyrene (13, 14). 

An imidazolide-supported polymer was used for transacylation of phosphatidylcholine. The polymer was obtained from a chloromethylated polystyrene with two mol-% divinylbenzene. The imidazolide group was anchored by reaction with 3-hydroxymethyl-1-tritylimidazole, cleavage of the trityl group, and condensation with palmitic acid 122]... 

Figure 34 A polymer-supported metallocene catalyst (51) with a weakly coordinating anion, [B(C6F5)4] , produced from lightly cross-linked, chloromethylated polystyrene beads for olefin polymerization. (Adapted from ref. 75.)...

Starting from the corresponding hydroxymethyl-benzocrown, it has been possible to generate the immobilized system (186) by reacting the above precursor with chloromethylated polystyrene (which is available commercially as Merrifield s resin). Typically, systems of this type contain a polystyrene matrix which has been cross-linked with approximately 1-4% p-divinylbenzene. In one study involving (186), a clean resolution of the alkali metal halides was achieved by HPLC using (186) as the solid phase and methanol as eluent (Blasius etal., 1980). In other studies, the divalent alkaline earths were also separated. 

In the case of the benzyloxytrityl-hydroxylamineresin 24b, the starting material is the Merrifield resin, chloromethylated polystyrene (1.7 mmol Cl x g 1) which is treated with 3 equiv. of 4-hydroxy-methyl benzoate in DMA with sodium methylate as base. The Beilstein test is used for monitoring and microanalyses showed the absence of chloride (Scheme 6). 

In 1983, Prasad et al.12 first reported the condensation of chloromethyl polystyrene with /V-hydroxyphthalimide to give the ester, hydrazinolysis of which yielded the desired resin-bound hydroxylamine. However, the sole purpose of this reagent was to react with, and hence extract ketones from, a complex steroidal mixture, and its use for the solid-phase synthesis of hydroxamic acids was not explored. Recently, the exploitation of the above solid-phase approach for the synthesis of hydroxamic acids was independently reported by three groups,7-9 all of which differ only in the method for the initial anchoring of TV-hydroxyphtha-limide to an 4-alkoxybenzyl alcohol functionalized polystyrene or trityl chloride polystyrene. Subsequent /V-deprotection was... 

Figure 9.2 Size exclusion chromatography traces for raw grafting products formed in the coupling reaction of chloromethylated polystyrene with polysty-ryllithium (a) without 1,1-diphenylethylene capping, and (b) with capped polystyryl anions (adapted from ref. [4])...

With a view to producing catalysts that can easily be removed from reaction products, typical phase-transfer catalysts such as onium salts, crown ethers, and cryptands have been immobilized on polymer supports. The use of such catalysts in liquid-liquid and liquid-solid two-phase systems has been described as triphase catalysis (Regen, 1975, 1977). Cinquini et al. (1976) have compared the activities of catalysts consisting of ligands bound to chloromethylated polystyrene cross-linked with 2 or 4% divinylbenzene and having different densities of catalytic sites ([126], [127], [ 132]—[ 135]) in the... 

Although phase transfer agents have been attached to clays, silica and alumina, the vast majority of studies have used organic polymers, especially polystyrene, as the support. The earliest of these triphase catalysts was prepared from 12% chloromethylated polystyrene crosslinked with 2% divinylbenzene by reaction with a tertiary amine. A wide range of triphase catalysts has since been reported, some examples of which are shown in Figure 5.16. 

From MetallatedPhosphines. The synthesis of polymeric tertiary phosphines based on the reaction of lithium diphenylphosphide with chloromethylated polystyrenes continues to attract interest.9 10 Considerable breakdown of the carbon-carbon back-bone of PVC occurs on reaction with lithium diphenylphosphide in THF, and only oligomers of low molecular weight result.11 The potassium salt (9) reacts with chloromethylated polystyrene to form the polymeric diphosphine (10).12... 

Widespread chlorine-containing polymers would include, 1) stable molding material for practical use such as polyvinyl chloride (PVC), polyvinylidene chloride and poly(epichlorohydrin)(PECH) and, 2) reactive polymers capable to introduce additional functional groups via their active chlorines such as chloromethyl polystyrene, poly (3-chloroethyl vinyl-ether) and poly (vinyl chloroacetate). While the latter, especially the chloromethyl polystyrene, has been widely used recently for the synthesis of variety of functional polymers, we should like to talk in this article about the chemical modification of the former, mainly of PVC and PECH, which was developed in our laboratory. 

The structure shown above is a representative of the class of lariat ethers we have called "nitrogen-pivot" compounds (31). The presence of invertable nitrogen as the point of sidearm attachment makes these compounds more flexible than the corresponding "carbon-pivot" lariat ethers (29,30). The carbon- and nitrogen-pivot lariat ethers have been prepared with a variety of sidechains attached. Examples of compounds which could be linked to existing polymers such as chloromethylated polystyrene or copolymerized with other monomers are shown below. 

Methods are now available for the synthesis of N substituted monoaza-crowns with >N(CH2CH20)jj-H sidearms (31). Such molecules could be attached to chloromethylated polystyrene as indicated in references 35-50. 

The direct quaternization of chloromethylated polystyrenes by tertiary amines or phosphines represents the easiest way to obtain polymer-supported quaternary onium salt (12,13). A lipophilic character of quaternary cation and a topology allowing sufficient cation-anion separation also play an important role (35,36). A linear spacer chain (of about 10 carbon atoms) between the catalytic site and the polymer backbone substantially increases the reaction rates. The loading of quaternary onium groups also affects catalytic efficiency, the influence being different for directly bonded and spaced groups, e.g. 10 and 11, respectively (37). 

Suitably functionalised crown-ethers and cryptands have been synthesi -ed and reacted with chloromethyl polystyrene. Initially... 

Smith and Liu have successfully prepared an unsymmetrical analog of a Katsui-type salen ligand possessing a hydroxyalkyl group in the 6-position, which facilitated the formation of an ester Hnkage to a polystyrene carboxyl chloride resin (Figure 5.19) derived from Merrifield s resin (chloromethylated polystyrene,... 

Finally, the lithiation of a soluble chloromethylated polystyrene 16 (prepared by AIBN-indnced copolymerization of styrene and 4-chloromethylstyrene in a 3 1 molar ratio) with lithinm and a catalytic amonnt of DTBB (10%) in THF at —78 °C gave the expected... 

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