Catalyst for oxidative polymerization

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

Electron transfer from the substrates to 02 proceeds by a redox cycle that consists of copper(II) and copper(I). The high catalytic activity of the copper complex can be explained as follows (1) The redox potential of Cu(I)/Cu(II) fits the redox reaction. (2) The high affinity of Cu(I) to 02 results in rapid reoxidation of the catalyst. (3) Monomers can coordinate to, and dissociate from, the copper complex, and inner-sphere electron transfer proceeds in the intermediate complex. (4) The complex remains stable in the reaction system. It may be possible to investigate other catalysts whose redox potentials can be controlled by the selection of ligands and metal species to conform with these requisites several other suitable catalysts for oxidative polymerization of phenols, such as manganese and iron complexes, are candidates on the basis of their redox potentials. 

In a mixture of water and water-miscible solvents such as acetone, 1,4-dioxane, and methanol, peroxidase could act as catalyst for oxidative polymerization of various phenol derivatives, yielding a new class of polyaromatics.4 The polymerization proceeds at room temperature, and during the polymerization, powdery polymers are often precipitated, which are readily collected after the polymerization. 

In living cells, various oxidoreductases play an important role in maintaining the metabolism of living systems. Most of oxidoreductases contain low valent metals as their catalytic center. In vitro enzymatic oxidoreductions have afforded functional organic materials. Some oxidoreductases such as peroxidase, laccase, and polyphenol oxidase have received much attention as catalysts for oxidative polymerizations of phenol derivatives to produce novel polyaromatics [1-10], This chapter deals with enzymatic oxidative polymerization of phenolic compounds. 

Tsuchida, E. Oyaizu, K. Kumaki, Y. Saito, K. Copper Complex Catalyst for Oxidative Polymerization of... 

FIGURE 4.9 Schematic representation of Cu -functionalized mesoporous silica (Cu-MSN) and alumina (Cu-MAL) catalysts for oxidative polymerization of 1,4-diethynylbenzene into conjugated oligofphenylene butadiynylene). (Figure modified from Reference 29.)... 

Peroxidase Model Catalyst. An iV,iV -bis(salicylidene)ethylenediamino iron [Fe(salen)] complex was found to be a cheap peroxidase model catalyst for oxidative polymerization of phenols with hydrogen peroxide (75-79). Hematin also polymerized ethylphenol in a reaction mechanism similar to that for HRP (80). 

Catalysts. Silver and silver compounds are widely used in research and industry as catalysts for oxidation, reduction, and polymerization reactions. Silver nitrate has been reported as a catalyst for the preparation of propylene oxide (qv) from propylene (qv) (58), and silver acetate has been reported as being a suitable catalyst for the production of ethylene oxide (qv) from ethylene (qv) (59). The solubiUty of silver perchlorate in organic solvents makes it a possible catalyst for polymerization reactions, such as the production of butyl acrylate polymers in dimethylformamide (60) or the polymerization of methacrylamide (61). Similarly, the solubiUty of silver tetrafiuoroborate in organic solvents has enhanced its use in the synthesis of 3-pyrrolines by the cyclization of aHenic amines (62). 

Diehlorotriphenylantimony has been suggested as a flame retardant (177,178) and as a catalyst for the polymerization of ethylene carbonate (179). Dihromotriphenylantimony has been used as a catalyst for the reaction between carbon dioxide and epoxides to form cycHc carbonates (180) and for the oxidation of a-keto alcohols to diketones (181). 

Yermakov, Yu.I., Chromium Oxide Catalysts for High Polymerization. Nauka, Novosibirsk, 1969. 

Phenol, the simplest and industrially more important phenolic compound, is a multifunctional monomer when considered as a substrate for oxidative polymerizations, and hence conventional polymerization catalysts afford insoluble macromolecular products with non-controlled structure. Phenol was subjected to oxidative polymerization using HRP or soybean peroxidase (SBP) as catalyst in an aqueous-dioxane mixture, yielding a polymer consisting of phenylene and oxyphenylene units (Scheme 19). The polymer showed low solubility it was partly soluble in DMF and dimethyl sulfoxide (DMSO) and insoluble in other common organic solvents. 

The above considerations stimulated investigations of the polymerization of model systems, namely ethylene oxide in the presence of dialkyldichlorostannanes30). R2SnCl2 has been found to be a very active catalyst for the polymerization of ethylene oxide, the polymerization rate increasing considerably with the length of the alkyl substituent at the tin atom. 

The initiation of polymerizations by metal-containing catalysts broadens the synthetic possibilities significantly. In many cases it is the only useful method to polymerize certain kinds of monomers or to polymerize them in a stereospecific way. Examples for metal-containing catalysts are chromium oxide-containing catalysts (Phillips-Catalysts) for ethylene polymerization, metal organic coordination catalysts (Ziegler-Natta catalysts) for the polymerization of ethylene, a-olefins and dienes (see Sect. 3.3.1), palladium catalysts and the metallocene catalysts (see Sect. 3.3.2) that initiate not only the polymerization of (cyclo)olefins and dienes but also of some polar monomers. 

Simple carboxylates of chromium(III) find industrial application as catalysts for the polymerization of to-alkenes854,855 and in the preparation of chrome-tanning solutions.856,857 There seems to be no simple carbonate of chromium(III). Compounds formed on the surface of Cr203, sometimes formulated Cr2(C03)3- H20, are best viewed as carbon dioxide adsorbed on the oxide.858 Carboxylate complexes of chromium(III) will now be considered in terms of the various ligand types. 

Diethyizinc is changed to an active catalyst for the polymerization of ethylene oxide and propylen oxide by reacting it with an appropriate amount of water, alcohol, acetone, amine, nitro compound, or nitroso compound. This type of catalyst gives high molecular weight (over one million) polymers from ethylene oxide and propylene oxide. 

In order to find a highly stereospedfic, homogeneous catalyst for the polymerization of propylene oxide, we selected the organometallic compound-primary amine catalyst system which exhibited excellent stereospecificity in the polymerization of acetaldehyde. 

Oguni,N., Tani,H. Nitrogen-containing organozinc and organoaluminum as catalyst for stereospedfic polymerization of propylene oxide (in preparation). 

Polymerization also takes place when 4-halo-2.6-disubstituted phenols are oxidized with copper-amine catalysts and oxygen (5,35). In this case, stoichiometric amounts of copper salt or some other chloride acceptor (inorganic bases or strongly basic amines) are necessary since the amine complexes of copper (II) halides are not catalysts for the polymerization. Blanchard (5) has also described the polymerization of these 4-halo-phenols under conditions similar to those used by Price using certain copper (II) complexes as initiators. 

Olefins - [FEEDSTOCKS - COALCHEMICALS] (Vol 10) - [FEEDSTOCKS-PETROCHEMICALS] (VollO) - [HYDROCARBONS - SURVEY] (Vol 13) -m automobile exhaust [EXHAUSTCONTROL, AUTOMOTIVE] (Vol 9) -catalyst for stereospeafic polymerization [TITANIUMCOMPOUNDS - INORGANIC] (Vol 24) -esters from [ESTERIFICATION] (Vol 9) -hydroxylation using H202 [HYDROGEN PEROXIDE] (Vol 13) -luminometer ratings [AVIATION AND OTHER GAS TURBINE FUELS] (Vol 3) -osmium oxidations of [PLATINUM-GROUP METALS, COMPOUNDS] (Vol 19) -polymerization [SULFONIC ACIDS] (Vol 23) -reaction with EDA [DIAMINES AND HIGHER AMINES ALIPHATIC] (Vol 8) -silver complexes of [SILVER COMPOUNDS] (Vol 22)... 

A supported catalyst for ethylene polymerization which requires no alkyl aluminum for activation was first claimed by the Phillips Petroleum Company (32). It consists of chromium oxide on silica, reduced with hydrogen. Krauss and Stach (93) showed that the active sites are Cr(II) centers. The presence of solvent, or even aluminum alkyls, diminishes... 

Many other chemical redox systems have been reported as initiators of macrocellulosic radicals and as catalysts for graft polymerization. One variation has been to modify cellulose chemically to increase its reactivity with selected oxidizing and reducing agents which on reaction yield macrocellulosic radicals (14, 15). 

Lanthanides as components in non-oxide systems As halides With co-catalysts for olefin polymerization in mixed halides for oxychlorination as supports... 

---