Polymerization of phenol

R often Me) formed by oxidative polymerization of phenols using oxygen with copper and an amine (pyridine) as catalysts. The products are thermoplastics used in engineering applications and in electrical equipment. 

The procedure of forming copolymers dates back to the early 1940s when only phenoHc resins were avaHable. Copolymers were produced by bulk polymerization of phenol [108-95-2] and formaldehyde [50-00-0]. Because the resulting soHd product had the shape of the vessel in which polymerization... 

Problem 31,11 Propose a mechanism to account for the formation of Bakelite from acid-catalyzed polymerization of phenol and formaldehyde. 

The control of the polymer structure was achieved by solvent engineering. The ratio of phenylene and oxyphenylene units was strongly dependent on the solvent composition. In the HRP-catalyzed polymerization of phenol in a mixture of methanol and buffer, the oxyphenylene unit increased by increasing the methanol content, while the buffer pH scarcely influenced the polymer structure. ... 

A bi-enzymatic system (glucose oxidase -I- HRP) was also used to catalyze the synthesis of phenolic polymers. The polymerization of phenol, albeit in moderate yield, was accomplished in the presence of glucose avoiding the addition of hydrogen peroxide (Scheme 2 ), which was formed in situ by the oxidation of glucose catalyzed by glucose oxidase. 

As described above, the enzymatic polymerization of phenols was often carried out in a mixture of a water-miscible organic solvent and a buffer. By adding 2,6-di-0-methyl-(3-cyclodextrin (DM-(3-CD), the enzymatic polymerization of water-insoluble m-substituted phenols proceeded in buffer. The water-soluble complex of the monomer and DM-(3-CD was formed and was polymerized by HRP to give a soluble polymer. In the case of phenol, the polymerization took place in the presence of 2,6-di-O-methyl-a-cyclodextrin (DM-a-CD) in a buffer. Only a catalytic amount of DM-a-CD was necessary to induce the polymerization efficiently. Coniferyl alcohol was oxidatively polymerized in the presence of a-CD in an aqueous solution. ... 

Morphology of the enzymatically synthesized phenolic polymers was controlled under the selected reaction conditions. Monodisperse polymer particles in the sub-micron range were produced by HRP-catalyzed dispersion polymerization of phenol in 1,4-dioxane-phosphate buffer (3 2 v/v) using poly(vinyl methyl ether) as stabihzer. °° ° The particle size could be controlled by the stabilizer concentration and solvent composition. Thermal treatment of these particles afforded uniform carbon particles. The particles could be obtained from various phenol monomers such as m-cresol and p-phenylphenol. 

The oxidative polymerization of phenols and anilines by enzymatic and chemical methods is an important method for synthesizing polyphenols50 and polyanilines51 in material research. Such polymerizations are often carried out in aqueous conditions. 

The net result is a decrease in initiator efficiency and an attendant increase in polymer molecular weight. In fact, all of our work on radical polymerization of phenol-containing vinyl monomers suggests that inhibition and transfer problems are at most minor, if AIBN is used as initiator and oxygen is carefully excluded from the reaction mixtures (9). 

The mechanism indicated in Figure 1 is postulated for the clay-catalyzed polymerization of phenols through radical cations. According to this scheme, an acceptor for one electron, such as Cu(II)... 

Figure 1. Postulated mechanism for the clay-catalyzed polymerization of phenols through radical cations.

Polymer-Copper Catalysts for Oxidative Polymerization of Phenol Derivatives... 

The Cu-complex-catalyzed oxidative polymerization of phenol derivatives has been selected here as a model reaction in which a polymer-metal complex acts as a catalyst. The catalytic cycle is illustrated in Scheme 3, the example used being the oxidative... 

Since the oxidative polymerization of phenols is the industrial process used to produce poly(phenyleneoxide)s (Scheme 4), the application of polymer catalysts may well be of interest. Furthermore, enzymic, oxidative polymerization of phenols is an important pathway in biosynthesis. For example, black pigment of animal kingdom "melanin" is the polymeric product of 2,6-dihydroxyindole which is the oxidative product of tyrosine, catalyzed by copper enzyme "tyrosinase". In plants "lignin" is the natural polymer of phenols, such as coniferyl alcohol 2 and sinapyl alcohol 3. Tyrosinase contains four Cu ions in cataly-tically active site which are considered to act cooperatively. These Cu ions are presumed to be surrounded by the non-polar apoprotein, and their reactivities in substitution and redox reactions are controlled by the environmental protein. 

Oxidative polymerization of phenol derivatives is also important pathway in vivo, and one example is the formation of melanin from tyrosine catalyzed by the Cu enzyme, tyrosinase. The pathway from tyrosine to melanin is described by Raper (7) and Mason (8) as Scheme 8 the oxygenation of tyrosine to 4-(3,4-dihydro-xyphenyl)-L-alanin (dopa), its subsequent oxidation to dopaqui-none, its oxidative cyclization to dopachrome and succeeding decarboxylation to 5,6-dihydroxyindole, and the oxidative coupling of the products leads to the melanin polymer. The oxidation of dopa to melanin was attempted here by using Cu as the catalyst. 

Synthesis of Poly(phenylene Oxides) by Electrooxidative Polymerization of Phenols... 

Recently much research has been made to coat electrodes with thin polymer films by electro-oxidative polymerization of phenols... 

The first application example is the electro-oxidative polymerization of phenol in the presence of 2,2-bis[3,5-dimethyl-4-hydroxyphenyl]-propane, which is the procedure to obtain terminally hydroxylated poly(phenyleneoxide), i.e. the oligomer contained two hydroxy groups per one molecule. 

The second example is the electro-oxidative polymerization of phenols bearing functional substituents. It is known that salicylic acid forms a stable chelate with copper ion, thus the copper catalyst is deactivated and the polymerization does not occur. On the other hand, salicylic acid was electro-oxidatively polymerized to produce the poly(phenyleneoxide) bearing carboxylic group. 

Figure 5. Scheme for the electro-oxidative polymerization of phenols. 

The refered oxidative polymerization of phenols with the copper-pyridine catalyst was carried out as in lit. (7,8). 

The polymerization of phenols or aromatic amines is applied in resin manufacture and the removal of phenols from waste water. Polymers produced by HRP-catalyzed coupling of phenols in non-aqueous media are potential substitutes for phenol-formaldehyde resins [123,124], and the polymerized aromatic amines find applications as conductive polymers [112]. Phenols and their resins are pollutants in aqueous effluents derived from coal conversion, paper-making, production of semiconductor chips, and the manufacture of resins and plastics. Their transformation by peroxidase and hydrogen peroxide constitutes a convenient, mild and environmentally acceptable detoxification process [125-127]. 

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... 

Phenolic polymers are obtained by the polymerization of phenol (/ = 3) with formaldehyde (/ = 2) [Bogan, 1991 Brydson, 1999 Kopf, 1988 Lenz, 1967 Manfredi et al., 2001 Peng... 

Wang,T.S.C. Huang, P.M. Chang-Hung Chou Jen-Hshuan Chen (1986) The role of sod minerals in the abiotic polymerization of phenolic compounds and formation of humic substances. In Huang, P.M. Sdmitzer, M. 

Peng Y, Liu HW, Zhang XY, Li YS, Liu SY (2009) CNT templated regioselective enzymatic polymerization of phenol in water and modification of surface of MWNT thereby. J Polym Sci A Polym Chem 47(6) 1627-1635... 

Dordick JS, Marietta MA, Klibanov AM (1987) Polymerization of phenols catalyzed by peroxidase in non-aqueous media. Biotechnol Bioeng 30 31-36... 

---