Merrifield chloromethylated resin

Subramanian and coworkers developed polymeric sorbents using different support materials (such as Merrifield chloromethylated resin, Amberlite XAD 16) and complexing ligands (amides, phosphonic acids, TTA), and evaluated their binding affinity for U(VI) over other diverse ions, even under high acidities. The practical utility of these sorbents was demonstrated using simulated waste solutions (220-222). Shamsipur et al. reported the solid-phase extraction of ultra trace U(VI) in natural waters using octadecyl silica membrane disks modified by TOPO (223). The method was found satisfactory for the extraction and determination of uranium from different water samples. 

Also, they prepared a new material by grafting Merrifield chloromethylated resin with octyl(phenyl)[(N,N-diisobutylcarbamoyl)methyl]phosphine oxide (Scheme 11.10). ... 

Raju et al. have synthesized a polyfunctional polymer containing diphos-phonic acid groups and dimethyl amino groups by grafting them onto the Merrifield chloromethylated resin (Scheme 11.16). ... 

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. 

Initial solid phase synthesis25 was carried out on Merrifield s resin (1 % crosslinked chloromethylated styrene/divinylbenzene copolymer, 200-400 mesh) because of its track record in solid-phase peptide synthesis.26 Unfortunately, the Merrifield resin has limitations as a carbohydrate carrier to study interactions between the carbohydrates and relevant binding proteins. The hydrophobic nature of the resin leads to nonspecific, irreversible protein adsorption.27 Later work utilized Rapp s TentaGel, an amphiphilic, polyethylene glycol resin.28... 

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,... 

NaHC03 (0.2 g) was added to a suspension of chloromethylated polystyrene-1 % divinylbenzene copolymer (Merrifield resin, 0.5 g, 0.76 mmol/g) in DMSO (3 mL). After stirring for 7 h at 155 °C, the resin was washed successively with H20, MeOH, DMF, CH2C12, and Et20 and then dried under reduced pressure. To confirm the conversion of the chloromethyl resin into the aldehyde resin, two analyses were used FTIR analysis showing the typical carbonyl absorption at 1700.5 cm-1 and microanalysis showing the absence of any chlorine on the resin. The benzaldehyde resin (1.0g, 0.59mmol/g) was suspended in... 

Solid supports ultimately require a functional group, e.g., an amino, hydroxyl, chloromethyl, or other functionality, that can be a starting point for SPPS. In some cases, a suitable functionalized monomer is included in the polymerization mix that gives the final support. Alternatively, the desired functional group can be introduced by a postpolymerization transformation [15]. The classic example of functionalization of a solid support is the chlo-romethylation of cross-linked polystyrene to produce chloromethyl-resin, also known as Merrifield resin [31]. This may then be modified further to introduce other functional groups such as aminomethyl or hydroxymethyl... 

Chloromethyl resin, Merrifield resin, a poly-styrene/divinylbenzene resin functionalized with the chloromethyl group introduced by Friedel-Crafts-type chloro-methylation with the aUcoxy-substituted chloromethane in the presence of tin(IV)... 

Today s chemists can buy Merrifield-type resins with varying degrees of chloromethyl substitution and cross linking tailored for specific purposes. Because the chlorine atom is primary and benzylic, these resins can be further modified by nucleophilic substitution. 

The design and application of new polymer supports for peptide synthesis remains a rapidly developing field. The use of glass beads coated with the polystyrene chloromethylated resin in a packed bed has been studied in detail. With a model tetrap>eptide the procedure was developed to a point where it became ten times faster than the usual Merrifield method but the average yield of each amino acid attachment was about 98.8% and the tetrapeptide... 

The Merrifield solid phase peptide synthesis requires the formation of an esterified resin as the first step. The substitution of an N-protected amino acid for a chloride in chloromethylated polystyrene must be quantitative or products which are one amino acid too short will ultimately be isolated. 18-Crown-6 has been shown to catalyze quantitative ester formation between the potassium salts of boc-amino acids and chloromethylated resin in DMF solution. Dichloromethane was reactive under these conditions [26]. The results of these displacement reactions according to equation 6.10 are presented in Table 6.8. 

The combination of a resin and covalently supported IL with SCCO2 was also used in the KR and dynamic kinetic resolution (DKR) of 1-phenylethanol with vinyl propionate catalyzed by Candida antarctica lipase B (CALB) [125]. The IL molecule covalently supported on Merrifield resin was realized through the reaction of 1-butyl imidazole with chloromethylated resin. Subsequently, NTf2 was introduced via ion exchange. Under improved conditions, the conversion of 1-phenylethanol was 50% with 99.9% ee to the product. In order to develop a more efficient process, the KR of 1-phenylethanol was tested on a flow system, and it remained stable for 6 days with 99% ee Moreover, by combing two fixed-bed reactors loaded with the supported enzyme (biocatalytic reactor, CALB-SILLP (SILLP, supported ionic liquid-like phase) 11, 150 mg) and an additional one with an acid zeolite (chemical racemization catalyst, 100 mg). Figure 2.40, the DKR of 1-phenylethanol... 

Polypeptide Synthesis and Analysis. Sihca or controUed-pore glass supports treated with (chloromethyl)phenylethyltrimethoxysilane [68128-25-6] or its derivatives are replacing chloromethylated styrene—divinylbenzene (Merrifield resin) as supports in polypeptide synthesis. The sdylated support reacts with the triethyl ammonium salt of a protected amino acid. Once the initial amino acid residue has been coupled to the support, a variety of peptide synthesis methods can be used (34). At the completion of synthesis, the anchored peptide is separated from the support with hydrogen bromide in acetic acid (see Protein engineering Proteins). 

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). 

Chloromethyl polystyrene (Merrifield resin) has been prepared by chloro-methylation of polystyrene [23,27,53,54], by copolymerization of 4-chloromethylsty-rene with styrene [20,26,55,56], and by chlorination of poly(4-methylstyrene) [57,58], Aminomethyl polystyrene is most conveniently prepared by direct amidomethylation of polystyrene with (hydroxymethyl)amides or (halomethyl)amides under acidic conditions followed by hydrolysis [59-62], but it has also been prepared directly from chloromethyl polystyrene ([63,64] see also Section 10.1.1.1). 

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