Copper oxidative coupling

Figure30.56 1, SAFT LC01 1.5 V (3.6Ah) lithium-copper oxide cell 2, alkaline K6 zinc-manganese dioxide cell. Capacity versus discharge current at various operating temperatures. The superiority of the lithium-copper oxide couple at low drain is evident (Courtesy...

The oxidative coupling of toluene using Pd(OAc)2 via />-tolylmercury(II) acetate (428) forms bitolyl[384]. The aryl-aryl coupling proceeds with copper and a catalytic amount of PdCl2 in pyridine[385]. Conjugated dienes are obtained by the coupling of alkenylmercury(II) chlorides[386]. 

Polymerization Mechanism. The mechanism that accounts for the experimental observations of oxidative coupling of 2,6-disubstituted phenols involves an initial formation of aryloxy radicals from oxidation of the phenol with the oxidized form of the copper—amine complex or other catalytic agent. The aryloxy radicals couple to form cyclohexadienones, which undergo enolization and redistribution steps (32). The initial steps of the polymerization scheme for 2,6-dimethylphenol are as in equation 6. 

The oxidative coupling of 2,6-dimethylphenol to yield poly(phenylene oxide) represents 90—95% of the consumption of 2,6-dimethylphenol (68). The oxidation with air is catalyzed by a copper—amine complex. The poly(phenylene oxide) derived from 2,6-dimethylphenol is blended with other polymers, primarily high impact polystyrene, and the resulting alloy is widely used in housings for business machines, electronic equipment and in the manufacture of automobiles (see Polyethers, aromatic). A minor use of 2,6-dimethylphenol involves its oxidative coupling to... 

There are many methods of fabricating the electrodes for these cell systems. The eadiest commercially successhil developments used nickel hydroxide [12054-48-7] Ni(OH)2, positive electrodes. These electrodes are commonly called nickel electrodes, disregarding the actual chemical composition. Alkaline cells using the copper oxide—2inc couple preceeded nickel batteries but the CuO system never functioned well as a secondary battery. It was, however, commercially available for many years as a primary battery (see BatterieS-PRIMARY cells). 

Poly(phenylene ether). The only commercially available thermoplastic poly(phenylene oxide) PPO is the polyether poly(2,6-dimethylphenol-l,4-phenylene ether) [24938-67-8]. PPO is prepared by the oxidative coupling of 2,6-dimethylphenol with a copper amine catalyst (25). Usually PPO is blended with other polymers such as polystyrene (see PoLYETPiERS, Aromatic). However, thermoplastic composites containing randomly oriented glass fibers are available. 

The Glaser reaction is an oxidative coupling of terminal alkynes 1 to yield a symmetrical Z -acetylene 2 the coupling step is catalyzed by a copper salt. Closely related is the Eglinton reaction, which differs from the Glaser reaction mainly by the use of stoichiometric amounts of copper salt as oxidizing agent. 

Katsuya et al. [5 published the oxidative coupling (agent copper(II) chloride/ aluminum chloride) of electron-rich benzene derivatives such as 2,5-dimethoxy-benzene to poly(2,5-dimethoxy-1,4-phenylene) (2). The resulting polymer is only soluble in concentrated sulfuric acid, and is fusible at 320r C. Ueda et al. 16] described the coupling of the same monomer with iron(III) chloride/aluminum chloride. The polymers obtained by the authors were not thoroughly para-linked. 

Copper oxide, oxidation of CO over, 86 Coupled heterogeneous catalytic reactions, kinetics of, 1-49, see also Kinetics coupling through catalytic surface, 9-13 experimental studies, 22-49 apparatus and procedure, 25, 26 catalysts, 26-28... 

Oxidative coupling of collagen Copper lysine oxidase (animals)... 

We were interested in the behaviour of polymeric catalysts in order to confirm that typical polymer effects may occur. Oxidative coupling of 2,6-disubstituted phenols, as developped by Hay (7), was chosen as a model reaction and the catalytic activities of coordination complexes of copper with several polymeric tertiary amines were compared with the activities of their low molecular weight analogs. The overall reaction scheme is presented in scheme 1. 

The basic study was performed on copper complexes with N,N,N, N1-tetramethylethane-1,2-diamine (TMED), which were known to be very effective oxidative coupling catalysts (7,12). From our first kinetic studies it appeared that binuclear copper complexes are the active species as in some copper-containing enzymes. By applying the very strongly chelating TMED we were able to isolate crystals of the catalyst and to determine its structure by X-ray diffraction (13). Figure 1 shows this structure for the TMED complex of basic copper chloride Cu(0H)Cl prepared from CuCl by oxidation in moist pyridine. 

So, both effects maintain an enlarged local concentration of active catalytic centers and cause the rate of oxidative coupling with polymeric catalysts to be higher than with equivalent amounts of low molecular weight analogs, especially for low 1igand/copper ratios. This rate enhancement is clearly demonstrated in Figure 5 for polydentates (I) vs. DMBA (J 7), and was also found for polydentate (II) vs. pyridine (18). 

Figure 8. Lineweaver-Burk plots for oxidative coupling of DPP catalyzed by copper complexes of polymer ligand (I) with a =0.39 at 5 different temperatures. [CuCle]0 = 3.3mM N/Cu = 1 solvent 1,2-dichlorobenzene/methanol (13 2,...

Figure 15.15. Copper cataly sed oxidative coupling of phenols...

---