Acrylates and acrylamides

Synthetic hydrogels have been frequently used in biomedical applications, because of the similarity of their physical properties to living tissues [3]. The most widely used synthetic hydrogels are polymers of acrylic acid, acrylamide, and 2-hydroxyethyl methacrylate (HEMA)  

For biomedical applications, the most frequently encountered synthetic hydrogel is poly(2-hydroxyethyl methacrylate) (pHEMA). The characterization and applications of pFIEMA have been reviewed [4]. Both HEMA and pHEMA are easy and inexpensive to produce. Because of the primary alcohol, the monomer or polymer can be functionalized. In addition, HEMA can be copolymerized 

Interesting properties can be engineered into these materials by copolymerization. Copolymerization of 2-ethylacrylic acid or MAA with iV-[4-(phe-nylazo)phenyl]methacrylamide, a photosensitive monomer, results in polymers in which the interaction with lipid biolayers can be photoregulated [10, 11]. Thermally reversible polymers can be produced from poly(iV-isopropylacryla-mide), which is a water-soluble polymer at room temperature. The LCST (lower critical solution temperature) of the homopolymer is 32 °C at this temperature a reversible phase separation occurs. This LCST can be adjusted by copolymerization with more or less hydrophilic monomers. 

Muzzarelli, R., In vivo biochemical significance of chitin-based medical items, in S,. Dumitriu, Polymeric Biomaterials. New York Marcel Dekker, 1994, pp. 179-197. 

Peppas, N.A., Hydrogels in Medicine and Pharmacy. Boca Raton, FL CRC Press, 1987. 

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Acrylate and acrylamide polymers have several uses in drilling fluids, one of which is for filtration control. Sodium polyacrylates [9003-04-7] having molecular weights near 250,000 are exceUent temperature-stable filtration control agents for both fresh- and salt water muds, provided the concentration of water-soluble calcium is <400 mg/L (83). The calcium ions are precipitated using a carbonate such as soda ash, before adding the polyacrylate at concentrations up to ca 6 kg/m (3 Ib/bbl). 

NMP with acrylates and acrylamides with TEMPO provides only very low conversions. Very low limiting conversions and broad dispersities were reported.2 Better results were obtained with DTBN (83),111 151 imidazoline (61-64)I3S and isoindoline (59) nitroxides.111 However, limiting conversions were still observed. The self-regulation provided in S polymerization by thermal initiation is absent and, as a consequence, polymerization proceeds until inhibited by the buildup of nitroxide. The final product is an alkoxyamine and NMP can be continued... 

In 2001, Mori et al. found that [Rh(OH)(GOD)]2 catalyzed the coupling of various acrylates and acrylamides with aryl silanediols, and the reaction could be controlled to give predominantly 1,4-addition products (Scheme 53) 142442a,i42b... 

Other monomers have been successfully grafted on polyamide under UV light sources. Hence, organic acids as acrylic (72,73), methacrylic (74), ftimaric (73), itaconic (73), and styrene sulfonic in 25% aqueous solution (73). Methyl acrylate and acrylamide in the presence of photosensitizers (74,75) and acrylonitrile (76) are reported as well. Heterocyclic derivatives as vinyl pyridine and vinyl pyrrolidone under UV light using photosensitizers as benzophenone were grafted on Nylon 66 cloth (77). 

Aziridines have been prepared on insoluble supports by addition of primary amines to a-bromo acrylates and acrylamides (Entry 6, Table 15.1). These aziridines are sufficiently stable to tolerate treatment with TFA [6],... 

Anionic Catalysis Several bulky methacrylates afford highly isotactic, optically active polymers having a single-handed helical structure by asymmetric polymerization. The effective polymerization mechanism is mainly anionic but free-radical catalysis can also lead to helix-sense-selective polymerization. The anionic initiator systems can also be applied for the polymerization of bulky acrylates and acrylamides. The one-handed helical polymethacrylates show an excellent chiral recognition ability when used as a chiral stationary phase for high-performance liquid chromatography (HPLC) [97,98]. 

The radical polymerization behavior of captodative olefins such as acrylonitriles, acrylates, and acrylamides a-substituted by an electron-donating substituent is reviewed, including the initiated and spontaneous radical homo- and copolymerizations and the radical polymerizations in the presence of Lewis acids. The formation of low-molecular weight products under some experimental conditions is also reviewed. The reactivity of these olefins is analyzed in the context of the captodative theory. In spite of the unusual stabilization of the captodative radical, the reactivity pattern of these olefins in polymerization does not differ significantly from the pattern observed for other 1,1-disubstituted olefins. Classical explanations such as steric effects and aggregation of monomers are sufficient to rationalize the observations described in the literature. The spontaneous polymerization of acrylates a-substituted by an ether, a thioether, or an acylamido group can be rationalized by the Bond-Forming Initiation theory. 

Similarly, acrylonitrile, methyl acrylate and acrylamide a-substituted with a benzyloxy group act as chain transfer agents during the polymerization of MMA, St, MA, and VA, which is due to the following fragmentation reaction [94] ... 

To achieve selectivity in these reactions, a steric or electronic bias is required to favour one particular product or (more importantly given the reversible nature of CM) one metal-alkylidene precursor in the catalytic cycle.1 In particular, it has been known for some time that metathesis reactions involving one highly electron deficient olefin partner can be selective (for the first example using acrylonitrile or styrene and 1 see Ref. [40]) however,readily available potential substrates such as enones, acrylates and acrylamides are generally incompatible with either 1 or 2 (for two reported exceptions see Ref. [41]). This was partially overcome by the use of acrolein acetals as a,/i-unsaturated car-... 

Alkoxy-l-boronobutadiene reacted with maleimides, acrylates, and acrylamides to provide cyclic allyl boronates which undergo allylboration with aldehydes (Equation (148)).409 Analogous syntheses of cyclic allylboron compounds via [2+4]-cycloaddition is discussed in Section 9.05.2.2.1. 

Many systems of this type exist, examples of which are Cr+ or Fe3+--thiourea (tested in polymerizations of acrylonitrile, methyl acrylate and acrylamide [44] Ce3+ with alcohols, aldehydes, amines, phosphates and carboxylic acids [45] V5+ with glycols, Mn3+ with dicarboxylic acid and their derivatives [46] Fe3+ with benzoin [47] etc. 

Acrylic acid is an important material for the chemical Industry, either as such or in (he form of acrylates and acrylamides. The Union Oil synthesis of acrylic acid from ethylene is performed at 140-150 C, 77 atm, C2 H4/CO 1 (Otalyst 0.1% PdOj. 0.5% CUCI2 in the presence of lithium acetate and chloride). The solvent is a mixture of acetic acid and acetic anhydride (about 20%) 24. The chemical steps of this Wacker-type catalysis are outlined ... 

A haloalkane with mixed halogens (1-7) led to living polymerization of methacrylates, acrylates, and acrylamides when coupled with ruthenium and nickel complexes.133 135 159 160 The weak C—Br bond is preferentially activated, while multifunctional initiation is possible. However, CCl3Br is the initiator of choice if obtaining narrow MWDs is desired without paying attention to monomer structures. 

Choi and co-workers [579] studied the reactivity of vinyl-terminated self-assembled monolayers (SAMs) of undec-lO-ene-1-thiol on gold (see Fig. 6.32) toward olefin cross-metathesis (CM). Vinyl groups on SAMs were successfully converted into a, P-unsaturated carbonyl groups by CM with acrylic acid, methyl acrylate, and acrylamide. Result shows that various useful functional groups can be introduced to SAMs on gold (and other solid surfaces) by olefin CM and suggests an alternative to the S3mthesis of desired molecules in solution [579]. 

The initial viscosity of resorcinol-formaldehyde grouts ranges from 1.5 to 3cP for concentrations normally used for field work, and like the acrylate and acrylamide grouts, the viscosity remains constant at those low levels until gelation starts. Again, like the acrylics, the change from liquid to solid is almost instantaneous. 

In the presence of Triton B, reaction of nitromethane with acrylonitrile affords tris-(2-cyanoethyl)nitromethane [4-(2-cyanoethyl)-4-nitroheptane-dinitrile].82 Nitroalkanes can also be added to acrylonitrile, ethyl acrylate, and acrylamide in liquid ammonia without addition of a catalyst 83 when... 

NMP willi acrylates and acrylamides with TEMPO provides only very low conversions. Very low limiting conversions and broad dispersities were... 

Similar to 4VBC couplings, acrylates and acrylamides are fairly easily accessible from an activated acryl donor such as acryloyl chloride or methacryloyl chloride and either an alcohol or an amine as the nucleophilic element. 

The mechanism of RAFT polymerization relies on activation of the monomer double bond to enable efficient fragmentation from the intermediate radical, which in turn provides control over the molecular weight of the resulting polymer. It follows that vinyl monomers, for which the double bond is not activated, are still challenging to polymerize efficiently via RAFT. Although attempts have been made to control the polymerization of 1-alkenes [16] and allyl butyl ethers [17], as yet only copolymerization with active monomers (acrylates and acrylamides) has led to a... 

SEimmes and coworkers have described the nonstereoselective conjugate addition of Grignard reagents, derived from 6,6-dibromopenicillanates, e.g. (68), to racemic a-sulfinyl acrylates and acrylamides such as (69) as part of a route to 6 -vinylpenicillinic acids (70) (Scheme 5.22) [67], which were potential antibiotics. Unfortunately, they possessed only weak antibiotic activity. 

The ort/to-alkylation of aromatic ketimines with functionalized olefins has been reported by Lim and co-workers. Among many olefin substrates bearing functional groups, acrylates and acrylamides showed good reactivity. The reaction could also be extended to other olefins, including phenyl vinyl sulfone and acrylonitrile, albeit with lower reactivity. The corresponding ketones were obtained after hydrolysis of the ketimines. 

Zhao, H., Cai, M.-Z., Peng, C.-Y and Song, C.-S. (2002) Palladium-catalyzed arylation of butyl acrylate and acrylamide with aryl iodides in water. J. Chem. Res. (S), 28-9. 

The batch emulsion copolymerisation of vinyl acetate and acrylic acid, methyl acrylate and acrylamide was investigated at 25C with a redox initiator system and a complex emulsifier. The kinetic behaviour of the copolymerisation and the structure of the resulting copolymers, as well as the particle size and number density of the latexes, were studied as a function of the conversion and the reaction time. 10 refs. 

Chemical Description Terpolymer of dimethyldiallyl ammonium chloride and sodium acrylate and acrylamide... 

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