Peroxidase-catalyzed polymerization of phenol

Ryu K, Stafford DR, Dordick JS (1989) Peroxidase-catalyzed polymerization of phenols. In Whitaker JR, Sonnet PE, (eds) Biocatalysis in agricultural biotechnology. American Chemical Society, Washington, D.C., p 141... 

Ryu. K.. D.R. Stafford, and J.S. Dordick Peroxidase-Catalyzed Polymerization of Phenols Kinetics of p-Cresol Oxidation in Organic Media, in Biocatalysis in Agncultural Biotechnology, J.R. Whitake, ed. ACS Symp. Ser. No. 389. 

Peroxidase-Catalyzed Polymerization of Phenolic Compounds Containing Carbohydrate Residues... 

Numerical and Monte Carlo simulations of the peroxidase-catalyzed polymerization of phenols were demonstrated.14 The monomer reactivity, molecular weight, and index were simulated for precise control of the polymerization of bisphenol A. In aqueous 1,4-dioxane, aggregates from p-phenylphenol were detected by difference UV absorption spectroscopy.15 Such aggregate formation might elucidate the specific solvent effects in the enzymatic polymerization of phenols. 

Peroxidase-catalyzed polymerization of phenols has provided a new methodology for functional polymeric materials. 

The enzymatic polymerization of phenols in aqueous solutions often resulted in low yield of the insoluble polymer. The peroxidase-catalyzed polymerization of phenol took place in presence of 2,6-di-O-methyl-a-cyclodextrin (DM-a-CD) in buffer [32], Only a catalytic amount of DM-a-CD was necessary to induce the polymerization efficiently. Even for water-insoluble m-substituted phenols, the addition of 2,6-di-0-methyl-(3-cyclodextrin (DM-P-CD) enabled the enzymatic polymerization in a buffer [33]. The water-soluble complex of the monomer and DM-P-CD was formed, which was polymerized by HRP to give a soluble polymer. Coniferyl alcohol was oxidatively polymerized in the presence of a-CD in an aqueous solution [34],... 

Peroxidase-catalyzed polymerization of phenols provided a new methodology for functional polymeric materials. Poly(oxy-2,6-dimethyl-l,4-phenylene) (poly(phenylene oxide), PPO) is widely used as a high-performance engineering... 

Typically, peroxidase-catalyzed polymerization of phenol is carried out in the presence of H2O2, which acts as an oxidizing agent. The free radicals of monomers (substrates) formed initially undergo coupling to produce dimers, and successive oxidation and coupling eventually results in the formation of polymers. The peroxidase-catalyzed polymerization of phenols and substituted phenols usually produce the polymer with complicated structures. The main structure was estimated to be of phenylene units or a mixture of phenylene and oxyphenylene units (5). 

The peroxidase-catalyzed polymerizations of phenols involve the formation of phenoxy radicals as an initial step. These radicals may either condense with each other or may be added to unsaturated compounds forming irregular high molecular polymers (see the biosynthesis of lignin, D 22.2.3). 

Most research in the field of peroxidase-catalyzed polymerization of phenols has been carried out withp-substituted phenols. In this case, the reactive para position of the phenol is blocked, so that the recombination of the phenol should take place mainly at the ortho positions of the phenols [88]. Thus, the structure of the resulting phenol polymers should not be as complicated as that for unsubstituted phenol. Scheme 8 shows the recombination process of a p-substituted radical (30). The radical form 31, having the radical stabilized at one of the two ortho positions, has the corresponding tautomeric form 36 and is the most stable (Scheme 8). Thus, the recombination should occur preferentially at the ortho positions. The mesomeric structure 32, having the radical in the meta positions, is less stabilized. The tautomeric structure 34, having the radical in the para position, should be more stable than 32 but less stable than structure 31. The mesomeric form is 33, having the radical stabilized at the oxygen atom (Scheme 8). 

The peroxidase-catalyzed polymerization of phenol and aniline derivatives has shown a lot of potential for the synthesis of new functional polymers under mild conditions, and for the environmentally friendly synthesis of phenol polymers without using toxic formaldehyde, as was shown in the previous paragraphs. The main drawback of this type of synthesis are therefore the cost and the handUng of the enzyme, although peroxidases are widely distributed in nature and HRP is extensively used commercially. 

During the last ten years, many research results have shown that oxidative polymerization catalyzed by peroxidases is a convenient, resource-saving, and environmentally friendly method for synthesizing phenol polymers. In contrast to the conventional synthesis of phenol-formaldehyde resins, the peroxidase-catalyzed polymerization of phenol proceeds under mild reaction conditions (room temperature, neutral pH). The polymerization of toxic phenols has promising potential for the cleaning of wastewaters. Moreover, the polymerization of phenols from renewable resources is expected to attract much attention in times of worldwide demand for the replacement of petroleum-derived raw materials. Besides the environment-protecting aspects of this innovative type of polymerization, the enzyme-catalyzed polymerization represents a convenient method to reahze new types of functional polyaromatic polymers. Phenol polymers made by peroxidase catalysis should have much potential for electronic and optical apphcations. The synthesis of functional phenol polymers is facihtated by the fact that poly-... 

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