Imidazole, vinyl

The nature of the interaction between the monomer and the template is more obvious in cases where specific ionic or hydrogen bonding is possible. For example, /f-vinyl imidazole has been polymerized along a PM A A template301 202 and acrylic acid has been polymerized on a Af-vinylpyrrolidone template.3 The daughter PAA had a similar degree of polymerization to the template and had a greater fraction of isotaclic triads than PAA formed in the absence of the template. 

A fluid loss additive useful in cementing oil and gas wells is a blend [423,424,1015] of a copolymer of acrylamide/vinyl imidazole. The second component in the blend is a copolymer of vinylpyrrolidone and the sodium salt of vinyl sulfonate. Details are given in Table 2-2. The copolymers are mixed together in the range of 20 80 to 80 20. Sodium or potassium salts or a sulfonated naphthalene formaldehyde condensate can be used as a dispersant. 

Table 4—3. Amides from l-acyl-4-vinyl imidazole/divinylbenzene copolymer.

As mentioned before for other azolide reactions, acylations can be carried out with polymer-supported azolides as acylating reagents. For example, acetic acid hydrazide can be prepared with a polymer of l-acetyl-4-vinyl-imidazole/divinylbenzene (96 4) and hydrazine (no diacylation occurs when this method is used) [122]... 

In this case, a moderately water-soluble amphiphilic N-vinylcaprolaclam (NVC1) played the role of a fl-unit, and a well-water-compatible N-vinyl-imidazole (NVIAz) served as a P-unil. The polymerization was carried out in a medium of 10% aqueous dimethylsulfoxide (DMSO). The addition of DMSO to the reaction solvent was necessary because of insufficient NVC1 solubility in pure water. It was also shown that in this solvent mixture, the NVCl-homopolymers and NVCl/NVIAz-copolymers retained their LCST-behaviour [26,28]. Hence, the DMSO in the reaction solvent did not significantly suppress the hydrophobic interactions of the NVC1 units. The polymerization was initiated by the redox system (N,N,N, N -tetramethylethylenediamine (TMEDA) + ammonium persulphate (APS)) and was carried out at 65 °C (1st step). This condition was very important, since admittedly the temperature was higher than the phase separation threshold of the reaction bulk when the polymeric products were formed that is, under these thermal conditions, hydrophobically-induced folding as the NVCl-blocks appear was ensured. After completion of the reaction, the... 

A synthesis of 5//-pyrrolo[l,2-r] imidazole 105 has been developed via a chemoselective addition/dehydration of acetaldehyde on diiodo imidazole 103 giving the vinylic imidazole 104. This compound, treated under the metathesis condition in the presence of the second-generation Grubbs catalyst, gave the final product 105 (Scheme 11) <2003TL1379>. 

Cycloaddition of nitrones (e.g. 166, equation 107) to alkoxyaUtenes proceeds in high yield with complete diastereoselectivity, giving 1,2-isoxazolidines of type 167. Similar reactions have been reported for vinyl ethers , vinyl acetate , enamines , vinyl imidazoles , enamides, vinyl sulfones and vinyl sulfides . Since the resultant 1,2-oxazolidines of type 167 and its analogs can be hydrolyzed under acidic conditions, this reaction may also be considered as an approach to O-unsubstituted N-alkylhydroxylamines . 

The lower the initiator concentration the higher the molecular weight of polymer formed. Moreover, the effect of the ratio template/monomer concentration is more pronounced for low initiator concentration. In addition, it was found that tacticity of the template does not influence the suppression of degradative addition nor the tacticity of the poly(vinyl imidazole) obtained by the template process. 

Significant research has been directed toward the use of polyelectrolyte complexes as blood compatible materials. Several investigators found that water-insoluble polyelectrolyte complexes can suppress blood coagulation [487-490]. Davison and coworkers reviewed and studied the biological properties of water-soluble polyelectrolyte complexes [491] between quatemized poly(vinyl imidazole) or polyvinyl pyridine) and excess sulfonated dextran or poly(methacrylic acid). By forming complexes with a stoichiometric excess of anionic charge, a more compact conformation with anionic character was obtained. 

Tsuchida et al. [33], synthesized Poly(l-vinyl and l-vinyl-2-methyl-imidazole) bound heme (iron-porphyrin) complexes as models for mimicking natural oxygen carriers such as hemoglobin. The reaction between AIBN polymerized poly(l-vinyl)imidazole, or poly(l-vinyl-2-methylimidazole) and Fe(III) protoporphyrin IX diethyl ester in DMF and small amount of Na2S204 yields the Fe(III) complex (Fig. 15),... 

Template Polymers. Template effects in chelating polymers constitute an interesting development in the field of metal containing polymers. The Template effects are interpreted by the fact that the small molecule is templating a pattern in the macromolecule which can be recognized by the same molecule in a subsequent process. The idea is to prepare a polymer from the metal-chelated monomer, to remove the metal ion, and then to measure the selectivity of the prepared polymer for the metal ion of the template [36]. Typical examples of template systems are 4-vinyl-4 -methylbipyridine (Neckers [36]) and 1-vinyl-imidazole (Tsuchida [37]). These are polymerized in presence of divinylbenzene [36] and appropriate metal salts (Co2+, Cu2+, Ni2+, Zn2+). The template metal ions are removed by acid leaching and the polymer subsequently used for metal ion absorption studies (Fig. 16). 

Experimentally, the described synthetic strategy was first realized by Lozinsky et al. [80,81], who studied the redox-initiated free-radical copolymerization of thermosensitive N-vinylcaprolac lam with hydrophilic N-vinyl-imidazole at different temperatures. These and other experimental studies [82 - 84] showed the universality of this approach of obtaining copolymers capable of forming nanostructures with a core-shell morphology. 

The hydrolysis of copolymers containing vinyl imidazole (Vim) as the third component, poly(MAOT-co-AA-co-VIm) (No. 15), poly(AOT-co-AA-co-VIm) (No. 13), and poly(MAOA-co-AA-co-VIm) (No. 17), is shown in Fig. 3. These copoly-... 

The increase of hydrophobicity in the substrate shows the increase in the binding. The hydrolysis of 3-nitro-4-acyloxy benzoic acid (8) by poly(4(5)-vinyl-imidazole) (II) is much influenced by the acyl chain length in the substrate (24,25, 56, 72). The increase of the acyl chain length makes the binding increase and the deacylation decrease. In the hydrolysis of the substrate having the longer acyl chain, a micelle effect should be considered. The hydrolysis is much influenced by the micelle formation. 

Both poly(l-butyl-5-vinylimidazole), poly(lB-5IM), and poly(l-methyl-5-vinyl-imidazole), poly(lM-5IM), have no quatemizable nitrogen, so that the coulombic interaction with the substrate is not necessarily to be considered. Using these polymers, hydrolyses of several 3-nitro-4-acyloxy benzoic acid having various acyl chain length (8) (n = 0,5,10,16) have been made (55). The apparent rates of hydrolyses are tabulated in Table 7. 

Poly(N-vinyl-imidazole) (PVI) and Poly(4(5)-vinyl-imidazole) (P4VI). . 62... 

Poly[4(5)vinyl-imidazole] can be obtained by radical polymerization of the corresponding monomer, in turn obtained by decarboxylation of transurocanic acid M> or by pyrolysis of 4 3-acetoxy)ethylimidazole 35). 

Cross-linked poly(N-vinyl-imidazole) was obtained by reaction of poly(N-vinyl-imidazole) with 1,4 dibromobutane37>. 

Poly(N-vinyl-imidazole) is an essentially monofunctional polybase, as shown by the sharpness of the jump in the titration curve 89). From conductance measurements, it was found that the data fitted the Henderson-Hasselbach expression with a term for the ionic strength ... 

In the case of Ag+, only two imidazolyl groups participate in complex formation, and the overall stability constant is log p2 = 8.00, about one order of magnitude larger than the overall formation constant of the Ag/imidazole complex (log p2 = 6.84). Complexes of Cu2 + with poly 4(5)-vinyl-imidazole, poly(N-vinyl-imidazole), and... 

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