Olefins, activated acrylamides

In order to incorporate polar-functionalized olefins, the catalyst system must exhibit tolerance to the functionality as described above. Therefore, polar monomer incorporation by the Ni(II) catalysts is generally not observed. Traces of methyl acrylate can be incorporated by the Ni(II) catalyst only under low loadings of that monomer [85], Acrylamide has been incorporated after prior treatment with tri-isobutylaluminum to block the amide donor sites, although polymerization activities are still relatively low [86], A similar protection of Lewis-basic functionalities by the coactivator has been cited to explain the copolymerization of certain monomers by early transition metal systems as well [40],... 

Colloidal platinum dispersions, prepated by photoreduction of tetrachloroplatina-te(II) ion in the presence of a copolymer of IV-vinyl-2-pyrrolidone and acrylamide, are treated with polyacrylamide gel having amino groups, resulting in stable immobilization of colloidal particles onto the gel. The immobilized catalysts exhibit high activities for the hydrogenation of olefins at 30 °C and 1 atm 87). 

Michael addition is a facile reaction between nucleophiles and activated olefins and alkynes in which the nucleophile adds across a carbon-carbon multiple bond [25], For the preparation of hydrogels, the hydroxyl, thiol or amine functionalities have been reacted with vinyl sulfones [26-28], acrylates [29-31], acrylamides [32], and maleimides [33, 34] (Scheme 2). 

As electron-rich olefins are more reactive, vinyl-sulfones are the most reactive species and are capable of reacting with thiols, amines, and even with small nucleophilic alcohol groups. Less reactive are acrylamides and acrylates, which are reactive towards amines and thiols. Maleimides are the least reactive of the mentioned species and allow selective addition of thiols in the presence of amines in the pH range 6.5-7.5. However, hydrolysis of the imide, especially at elevated pH values [35], may be a concern for certain applications. The mentioned Michael addition reactions do not require organic solvents and can be carried out at physiological temperature and pH [36], In acidic conditions, the reaction is either very slow or does not proceed because protonation removes the nucleophilic form in the case of amines, and the thiolate anion is usually the active species in Michael additions involving thiols [25],... 

The compound was used as a catalyst for the hydrogenation of olefins. No rhodium was lost. This type of polymer shows inverse temperature solubility. When the temperature was raised, the polymeric catalyst separated from solution for easy recovery and reuse. This type of smart catalyst will separate from solution if the reaction is too exothermic. The catalytic activity ceases until the reaction cools down and the catalyst redissolves. Poly (A i sop ropy lacrylamide) also shows inverse temperature solubility in water. By varying the polymers and copolymers used, the temperature of phase separation could be varied (e.g., from 25 to 80°C).214 A terpolymer of 2-isopropenylan-thraquinone, A-isopropylacrylamide, and acrylamide has been used in the preparation of hydrogen peroxide instead of 2-ethylanthraquinone.215 The polymer separates from solution when the temperature exceeds 33 C to allow re-... 

Aggarwal and co-workers have examined the correlation of the pATa of various quinuclidine-based catalysts (Figure 2.1) with their reactivities in the MBH reaction. They found that quinuclidine (QD), which was previously reported as a poor catalyst, in protic solvents has the highest (II.3/H2O) and is the most active catalyst for this reaction. They also observed that the combination of quinuclidine and methanol was the most efficient system for catalyzing the MBH reaction. Various activated olefins, including less reactive activated olefins such as vinyl sulfones, acrylamides and p-substituted a,p-unsaturated esters, have also been employed in this reaction, using quinuclidine as a catalyst (Scheme 2.32). ... 

The reaction was extended to the coupling of alkenes and isocyanates to provide a,p-acrylamides. The most active catalyst was [(IPr)Ni] that allowed a good regioselectivity at the 2-position of the olefin (Equation (10.31)) and deprotection of the obtained products afforded the corresponding primary amides. 

The polymers most investigated up to now are those derived from optically active a-olefins, vinyl ethers, vinyl ketones, acrylic or methacrylic esters, acrylamides, and aldehydes. As indicated in Table 4, isotactic and, in certain cases,isotactic and syndiotactic polymers have been obtained by using stereospecific processes. The stereospecific processes used with these chiral monomers are the same as those employed for producing stereoregular polymers from the corresponding achiral monomers. 

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