Substitution reactions of poly

T. Nishikubo, T. lizawa, K. Kobayashi, and M. Okawara, Substitution reaction of poly(chloromethyl-... 

The polymer, [-CH2CH(CH2NHC6H4N02-p)-]n, PPNA, was synthesized by aromatic nucleophilic substitution reaction of poly(allylamine hydrochloride) with p-fluoronitrobenzene. PPNA so prepared has mol. wt. 

Discuss nucleophilic substitution reactions of poly(methyl methacrylate), the Amdt-Eister reactions of poly(methacryloyl chloride), and the Curtius and Lossen rearrangements of poly(acryloyl chloride). 

The same reaction, carried out with conventional heating at the same temperature, took more that 6 h to give comparable yields of the products. Dihydropyrazoles were also obtained by microwave-assisted reaction of poly-substituted vinyl ketones 122 with hydrazines, followed by reaction of the unstable pyrazole 123 with electrophiles (Scheme 43) [80]. 

Alternatively, esterification of carboxylic acid can be carried out in aqueous media by reacting carboxylic acid salts with alkyl halides through nucleophilic substitutions (Eq. 9.10).20 The reaction rate of alkyl halides with alkali metal salts of carboxylic acids to give esters increases with the increasing concentration of catalyst, halide, and solvent polarity and is reduced by water. Various thymyl ethers and esters can be synthesized by the reactions of thymol with alkyl halides and acid chlorides, respectively, in aqueous medium under microwave irradiation (Eq. 9.11).21 Such an esterification reaction of poly(methacrylic acid) can be performed readily with alkyl halides using DBU in aqueous solutions, although the rate of the reaction decreases with increasing water content.22... 

In addition to providing many new precursors to functionalized poly(alkyl/arylphosphazenes), the deprotonation/substitution reactions of these N-silylphosphoranimines serve as useful models for similar chemistry that can be carried out on the preformed polymers. New reactions and experimentation with reaction conditions can first be tried with monomers before being applied to the more difficult to prepare polymeric substrates. A considerable amount of preliminary work [e.g., with the silylated monomers (z z) and polymers (2 o) has demonstrated the feasibility of this model system approach. 

This article reports on the synthesis of photosensitive polymers with pendant cinnamic ester moieties and suitable photosensitizer groups by cationic copolymerizations of 2-(cinnamoyloxy)ethyl vinyl ether (CEVE) (12) with other vinyl ethers containing photosensitizer groups, and by cationic polymerization of 2-chloroethyl vinyl ether (CVE) followed by substitution reactions of the resulting poly (2-chloroethyl vinyl ether) (PCVE) with salts of photosensitizer compounds and potassium cinnamate using a phase transfer catalyst in an aprotic polar solvent. The photochemical reactivity of the obtained polymers was also investigated. 

Water-soluble polymer-bound porphorins have been prepared by the reaction of poly(methacrylic acid) and poly(N-vinyl pyrrolidone-co-methacrylic acid) with the low-molecular weight substituted Zn complexes tetraphenylpor-phorin, phthalocyanins and naphthocyanins [67, 68]. These reactions are... 

The rates of complex formation and ligand substitution reactions of the polymer-bound Co(III) complexes depend on the dynamic property of the polymer domains. Reports on the kinetics of complex formation and ligand substitution of macromolecule-metal complexes are, however, relatively scarce. They include investigations on the complexation of poly-4-vinylpyridine with Ni2+ by the stopped conductance technique 30) and on a ligand substitution reaction of the polymer-bound cobalt(III) complexes 31>. 

Figure 9.5 Reactions of poly ion interchange (A) poly ion exchange resulting in uniform distribution of polycation among DNA chains (B) polyion substitution resulting in recognition of the scDNA and release of the 1DNA in a free form.

Investigation of the kinetics of the reaction of 4-chloro-2-pentene, an allylic chloride model for the unstable moiety of polyfvinyl chloride), with several thermal stabilizers for the polymer has led to a better understanding of the stabilization mechanism. One general feature of the mechanism is complexing of the labile chlorine atom by the metal atom of the stabilizer. A second general feature is substitution of the complexed chlorine atom by a ligand (either carboxylate or mercaptide) bound to the metal. Stabilization requires that the new allylic substituent (ester or sulfide) be more thermally stable than the allylic chlorine. The isolation of products from stabilizer-model compound reactions supports the substitution hypothesis of poly(vinyl chloride) stabilization. 

In regard to substitution reactions of the functional phenyl groups, poly(diphenylsilylene-co-methylene) is a very interesting educt for the preparation of modified polycarbosilanes as precvirsors for SiC-based ceramic fibers. 

Amino, alkoxy, and aryloxy polyphosphazenes are typically prepared by nucleophilic displacement reactions of poly(dihalophosphazenes). Analogous reactions with organometallic reagents, however, result in chain degradation and cross linking rather than in linear, alkyl, or aryl substituted poly(phosphazenes). The thermolysis of appropriate silicon-nitrogen-phosphorus compounds can be used to prepare fully P—C bonded poly(organophosphazenes). The synthesis of two of these materials and their Si—N—P precursors is described here. 

The substitutive addition reactions of poly-aromatic radicals on methyl and alkyl positions of aromatic species produce poly-aromatic structures, as... 

The reaction of poly(methyl acrylate)-Br with 2-aminoethanol was expected to result in multiple substituted products. This result was ascribed to the fact that after the substitution of the bromine by 2-aminoethanol, formation of a six-membered ring could occur (Scheme 18). Afterwards, ring opening by attack of a second 2-aminoethanol molecule could lead to the double-substituted product. The a-bromo poly(methyl acrylate) could be suppressed by using 4-aminobutanol instead of 2-aminoethanol as a nucleophile, without side reactions (Scheme 18). For example, the yield of functionalization of poly( -butyl acrylate) with 5-amino-l-pentanol is close to 96% [197]. 

Poly(dichlorophosphazene) by itself is not useful since it is hydrolytically unstable. This however implies a high reactivity of the P-Cl bonds, a characteristic which implies the possibility of facile nucleophilic substitution reactions of chlorines by hydrolytically stable organic groups (Scheme 10). Also, the macromolecular... 

The synthesis of poly(phosphazene) derivatives by single or multistep reactions of poly(phosphazene) precursors continues to represent the major pathway to new members of this class of materials. The reaction of an oxyanion with (NPClj) is the most common synthetic procedure in this area. Protected glyceral poly(phosphazenes) analogous to the cyclic homologs, 28, have been prepared and may be crosslinked by exposure to yi radiation. Acidic deprotection yields the free glyceral substituted polymers which undergo slow hydrolysis. The deprotected polymers can be crosslinked using... 

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