Chemical oxidative coupling

Methods for disposing of diisopropyl methylphosphonate include microwave decomposition, ultraviolet and infrared laser-induced photodestruction, chemical oxidation coupled with ultraviolet radiation catalyzation, and adsorption using granular activated carbon (Bailin et al. 1975 Calgon 1977 ... 

Anodic and chemical oxidative coupling of homolaudanbsine (158 R = Me) yields homoglaucine, but oxidation of N-acyl-nor-analogues, e.g. (158 R = COF3), by vanadium oxyfluoride in trifluoroacetic acid and anhydride affords a... 

Various mechanisms have been proposed for the anodic polymerization of benzene, involving successive electrochemical (E) and chemical (C) steps, and basically, they do not differ markedly from those which were proposed in the chemical oxidative coupling of Kovacic, except that in this case the chemical oxidation step is replaced by an electrochemical reaction. However, a great difference is observed between neutral and acidic media, with, in particular, an important reduction of the oxidation potential of benzene in the presence of strong acids. 

The same analysis has been made on polymers pA3Th-Cl and pA3Th-Cl (Table 14.16) prepared by chemical oxidative coupling using FeCl3 of a-hydro-genated and a-silylated monomers, respectively. The low-temperature photoluminescences taken on these two polymers are shown in Figure 14.40. 

First, it is interesting to compare the photoluminescence measured on pA3Th-Cl and pA3Th-C2 polymers, respectively, both polymers being prepared by chemical oxidative coupling of a-silylated monomers. The two photoluminescences are similar there are the same position of the peaks (1.95 0.01 eV), the same progression in die relative intensity of the well-resolved peaks, the same width of the 0-phonon line (65 5 meV). 

The Layer-by-Layer Deposition Method [557]. This method, based on the chemical oxidative coupling polymerization reaction, enables the simultaneous synthesis and deposition of a thin film of different insoluble conducting polymers in the conducting state such as PMT and PBT. Films (40-1000 nm thick)... 

Soon after this, the synthesis of polymers 15a and b was reported (Figure 8.13) [52]. Random copolymers were obtained by chemical oxidative coupling. Different fullerene loadings were obtained by different fullerene-bearing monomer ratios... 

The regioselectivity and syn stereochemistry of hydroboration-oxidation coupled with a knowledge of the chemical properties of alkenes and boranes contribute to our under standing of the reaction mechanism... 

Semicommercial production of 3,3/4,4 -biphenyltetracarboxyhc dianhydride [2420-87-3] in the United States has been announced by Occidental Chemical Corp. (74). This polyimide resin intermediate is prepared by dehalogenative dimerization of 4-chlorophthalate salts (75) or by oxidative coupling of phthalate esters (76). 

Polyheterocycles. Heterocychc monomers such as pyrrole and thiophene form hiUy conjugated polymers (4) with the potential for doped conductivity when polymerization occurs in the 2, 5 positions as shown in equation 6. The heterocycle monomers can be polymerized by an oxidative coupling mechanism, which can be initiated by either chemical or electrochemical means. Similar methods have been used to synthesize poly(p-phenylenes). 

The synthesis involves the nickel-catalyzed coupling of the mono-Grignard reagent derived from 3-alkyl-2,5-diiodothiophene (82,83). Also in that year, transition-metal hahdes, ie, FeCl, MoCl, and RuCl, were used for the chemical oxidative polymerization of 3-substituted thiophenes (84). Substantial decreases in conductivity were noted when branched side chains were present in the polymer stmcture (85). 

A High-Energy Chemical Intermediate Coupling Oxidation and Phosphorylation Proved Elusive... 

Masuda, T. et ah. Chemical studies on antioxidant mechanism of curcumin analysis of oxidative coupling products from curcumine and linoleate, J. Agric. Food Chem., 49, 2539, 2001. 

Corrosion (from Latin corrodere, gnaw to pieces ) of metals is the spontaneous chemical (oxidative) destruction of metals under the elfect of their environment. Most often it follows an electrochemical mechanism, where anodic dissolution (oxidation) of the metal and cathodic reduction of an oxidizing agent occur as coupled reactions. Sometimes a chemical mechanism is observed. 

Techniques for attaching such ruthenium electrocatalysts to the electrode surface, and thereby realizing some of the advantages of the modified electrode devices, have been developed.512-521 The electrocatalytic activity of these films have been evaluated and some preparative scale experiments performed. The modified electrodes are active and selective catalysts for oxidation of alcohols.5 6-521 However, the kinetics of the catalysis is markedly slower with films compared to bulk solution. This is a consequence of the slowness of the access to highest oxidation states of the complex and of the chemical reactions coupled with the electron transfer in films. In compensation, the stability of catalysts is dramatically improved in films, especially with complexes sensitive to bpy ligand loss like [Ru(bpy)2(0)2]2 + 51, 519 521... 

GTG [gas to gasoline] A process for converting natural gas to gasoline by oxidative coupling. Ethylene, formed initially, is oligomerized to a gasoline-like distillate over a zeolite catalyst. Under development by the Arco Chemical Company in 1988. 

Oxco [Oxidative coupling] A process for converting natural gas to transport fuels and chemicals, based on the oxidative coupling of methane to ethane in a fluidized-bed reactor. Developed in Australia by the Division of Coal and Energy Technology, CSIRO, and BHP. 

For illustration, we consider a simplified treatment of methane oxidative coupling in which ethane (desired product) and CO, (undesired) are produced (Mims et al., 1995). This is an example of the effort (so far not commercially feasible) to convert CH, to products for use in chemical syntheses (so-called Q chemistry ). In this illustration, both C Hg and CO, are stable primary products (Section 5.6.2). Both arise from a common intermediate, CH, which is produced from CH4 by reaction with an oxidative agent, MO. Here, MO is treated as another gas-phase molecule, although in practice it is a solid. The reaction may be represented by parallel steps as in Figure 7.1(a), but a mechanism for it is better represented as in Figure 7.1(b). 

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