Substitution reaction of polymers

Substitution Reactions of Polymers with Aromatic Rings... 

Production of substituted poly (aniline) s seem to be straight forward and it can be generated via oxidative polymerization of corresponding monomer. However, in many cases the desired substituted polymer is hard to obtain. In present investigation PANI(s) have been prepared chemically by direct oxidation of aniline and electrochemical oxidation of aniline on GC electrode. The substitution reaction of polymer with 3-chloropropylthiol and ferric chloride occurred via Friedel-Craft mechanism. Although for bulk chemically prepared polymer this method is restricted due to low to mod-... 

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. 

The polymers used in this study were prepared by a nucleophilic activated aromatic substitution reaction of a bisphenate and dihalo diphenyl sulfone ( ). The reaction was carried out in an aprotic dipolar solvent (NMP) at 170°C in the presence of potassium carbonate (Scheme 1) (5,6). The polymers were purified by repeated precipitation into methanol/water, followed by drying to constant weight. The bisphenols used were bisphenol-A (Bis-A), hydroquinone (Hq) and biphenol (Bp). Thus, the aliphatic character of Bis-A could be removed while retaining a similar aromatic content and structure. The use of biphenol allows an investigation of the possible effect of extended conjugation on the radiation degradation. 

This approach can be illustrated by describing the preparation of the polymer rhodium catalyst II (Sec. 9-lg). The synthesis is based on a nucleophilic substitution reaction of chlor-omethylated polystyrene [Grubbs and Kroll, 1971] ... 

A Co(IH) complex is inert in ligand-substitution reactions, and its uniform structure is thus maintained even in an aqueous solution. The reaction mechanism of a Co(III) complex in solution is well known, so that a pendant-type polymer-Co(IU) complex, e.g. 17,19, is one of the most suitable compounds for a quantitative study of the effects of a polymer ligand on the reactivity of a metal complex. The reactivities of the polymer-Co(III) complexes are discussed here kinetically and compared with those of the monomeric Co(III) complexes in the following reactions electron-transfer reactions between the polymer complexes and Fe(II) [Eqs. (5) and (6)], and the ligand-substitution reaction of the polymer-Co(III) complex with hydroxy ions or water [Eqs. (7) and (8)J. One of the electron-transfer reactions proceeds via... 

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. 

Syntheses of Polymeric Photosensitizers and Self-sensitized Polymers by the Reactions of PCVE. Photosensitizer monomers such as NPVE, NNVE and NPEVE were synthesized by the reaction of excess CVE with potassium salts of the corresponding photosensitizing compounds using TBAB as a phase transfer catalyst as described in the experimental part. Substitution reactions of chloroethyl groups in PCVE with PNP and PNN were also carried out using TBAB as a phase transfer catalyst in DMF at 80 C for 24 h. 

A polyethylene glycol-polystyrene graft copolymer palladium catalyst has been used in allylic substitution reactions of allyl acetates with various nucleophiles in aqueous media.58 Another polymer-bound palladium catalyst 40 was developed and used in a Heck coupling of allylic alcohols with hypervalent iodonium salts to afford the substituted allylic alcohols as the sole products under mild conditions with high catalytic efficiency.59 The same polymer-bound palladium catalyst has also been used for Suzuki cross-coupling reactions.60... 

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>. 

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. 

For example, polymers having hydroxyl end groups can be prepared by reaction of polymer lithium with epoxides, aldehydes, and ketones III-113). Carboxylated polymers result when living polymers are treated with carbon dioxide (///) or anhydrides (114). When sulfur (115, 116), cyclic sulfides (117), or disulfides (118) are added to lithium macromolecules, thiol-substituted polymers are produced. Chlorine-terminus polymers have reportedly been prepared from polymer lithium and chlorine (1/9). Although lithium polymers react with primary and secondary amines to produce unsubstituted polymers (120), tertiary amines can be introduced by use of p-(dimethylamino)benzaldehyde (121). 

It has been shown that during sulfur vulcanisation of EPDM the C=C peak of the residual ENB unsaturation at 1685 cm 1 seems to decrease in intensity in agreement with the observations by Fujimoto and co-workers [73,74] (see Section 6.2.2.1). However, in Section 6.2.2.2 it was shown that sulfur vulcanisation of the low-molecular-weight ENBH results in a shift of the Raman C=C peak from 1688 to 1678 cm 1. Taking this into account a closer inspection of the FT-Raman spectra reveals that the original C=C peak at 1690 cm"1 decreases in intensity, and a new peak is observed at 1681 cm"1. Actually, the C=C peak broadens towards lower wave numbers, but in a first approximation the total area remains constant. So, the sulfur substitution reaction of the allylic hydrogens is confirmed for the polymer system. This corresponds to the observation by Koenig and co-workers, namely that upon sulfur vulcanisation of cz s-BR, the C=C peak at 1650 cm 1 decreases in intensity and that of a new peak at 1633 cm-1 increases its intensity [19, 58]. 

Epoxides are important intermediates in many industrial processes. For example, the reaction of the simplest epoxide, ethylene oxide, with water is employed to produce ethylene glycol, which is used in antifreeze and to prepare polymers such as Dacron. One method for the preparation of ethylene oxide employs an intramolecular nucleophilic substitution reaction of ethylene chlorohydrin ... 

As mentioned previously, selective intermacromolecular complexation is realized by the control of the difference of the total bond energy between each pair of polymers. Therefore, if P can interact with P2 more strongly than P3 does, the interchain macromolecular substitution reaction of P3 and P3 takes place on the addition of Pj to the P2-P3 complex solution. In these systems, it is expected that a cooperative interchain macromolecular substitution reaction of the type... 

It was also found [13] that triphenylselenonium chloride and its polymer analogue 40 work as highly efficient phase-transfer catalysts even in the presence of a strong base, thus allowing, for example, the phenoxide substitution reaction of 1-bromooctane [13bj. 

Solid-phase synthesis of substituted pyrazolones 550 from polymer-bound /3-keto esters 549 has been described (Scheme 68) <2001EJ01631>. Trisubstituted pyrazole carboxylic acids were prepared by reaction of polymer-bound arylidene- or alkylidene-/3-oxo esters with phenylhydrazines <1999S1961>. 2-(Pyrazol-l-yl)pyrimi-dine derivatives were prepared by cyclocondensation of ethyl acetoacetate and (6-methyl-4-oxo-3,4-dihydropyrimi-din-2-yl)hydrazine with aromatic aldehydes <2004RJC423>. Reactions of acylated diethyl malonates with hydrazine monohydrochloride in ethanol afforded 3,4-disubstituted-pyrazolin-5-ones <2002T3639>. Reactions of hydrazines with A -acetoacetyl derivatives of (45 )-4-benzyloxazolidin-2-one (Evans oxazolidinone) and (2R)-bornane-10,2-sultam (Oppolzer sultam) in very acidic media gave pyrazoles retaining the 3(5)-chiral moiety <1999S157>. 

A nonpolar solvent favors conformation A, whereas conformation B is favored by more polar solvents (e.g. dimethylformamide, hexamethylphosphoric triamide) because the cation is more solvated (cf. Table 9, entries 1 and 2). However, this solvent effect is absent when BujP Cu" is used as counterion. Conformation A is more favored by relatively small counterions, such as the lithium and sodium ion, as compared to the larger potassium ion, due to the higher degree of association of the former. Steric strain between ASG and ASG is minimized in conformation B. Conformations A and B lead to trans- and c -substituted cyclopropanes, respectively. A study of cyclopropane esters, -in which the stereoselectivity of the reaction of polymer-supported reagents was compared with molecules of low-molecular weight, made clear that the steric and polar microenvironment of the polymer-supported reaction is not different enough in bulk to influence the selectivity substantially. Nevertheless, a specific influence of the solid phase can be observed at low temperatures. 

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