Copper catalytic conditions

A convenient synthesis of organochlorosilanes from organosilanes is achieved by reaction with inorganic chlorides of Hg, Pt, V, Cr, Mo, Pd, Se, Bi, Fe, Sn, Cu, and even C. The last compounds, tin tetrachloride, copper(II) chloride, and, under catalytic conditions, carbon tetrachloride (117,118), are most widely used. 

Terminal alkynes are converted in high yield (70-80%) into 1-iodoalkynes by their copper-catalysed reaction with iodine under phase-transfer catalytic conditions... 

More recent investigations have shown that this reaction operates even under catalytic conditions (3-10 mol% of copper(II) salt), with alkylzinc reagents as the stoichiometric organometallic source (Scheme 6.42) [89]. 

Infrared spectra of propene and isobutene on different catalysts were measured by Gorokhovatskii [143]. Copper oxide, which converts olefins to butadiene and aldehydes, shows adsorption complexes different from structures on a V2Os—P2Os catalyst which produces maleic acid anhydride. Differences also exist between selective oxidation catalysts and total oxidation catalysts. The latter show carbonate and formate bands, in contrast to selective oxides for which 7r-allylic species are indicated. A difficulty in this type of work is that only a few data are available under catalytic conditions most of them refer to a pre-catalysis situation. Therefore it is not certain that complexes observed are relevant for the catalytic action. 

Oxazoles of various substitution patterns are well known heterocycles for which a number of methods of synthesis have been reported.129 Acyl carbenes or functionally equivalent species have been found to undergo cyclization with nitriles to give oxazoles in high yield via nitrile ylide intermediates.130,131 This reaction can be induced to occur under thermal, photolytic, or catalytic conditions.129,132,133 Huisgen and coworkers were the first to study this process in some detail.132 Thermolysis (or copper catalysis) of a mixture of ethyl diazoacetate and benzonitrile resulted in the formation of oxazole 254. The isolation of this product is... 

Coupling of allylic or propargylic halides and terminal acetylenes can also be realized under completely catalytic conditions [204,205]. The reactions are carried out in aqueous medium in the presence of catalytic amounts of copper(I)haUde. The hydrogen halide liberated in the reaction is neutralized with ammonia, an amine or alkali hydroxide. In many cases both the 1,1- and the 1,3-coupling product is obtained ... 

This alkoxy derivative of copper is obviously not stable in the presence of too much water its presence under catalytic conditions has been confirmed by the parallel formation of some alkoxycarbonate probably through the known reaction ... 

Methylene ( CH2) generated photochemically or thermally from diazomethane is highly reactive and is prone to incur side reactions to a substantial extent. In order to avoid these undesirable complexities, the cyclopropanation of multiple bonds with diazomethane has usually been carried out under catalytic conditions The catalysts most frequently employed are copper salts and copper complexes as well as palladium acetate. The intermediate produced in the copper salt-catalyzed reactions behaves as a weak electrophile and exhibits a preference to attack an electron-rich double bond. It is also reactive enough to attack aromatic nuclei. In contrast, the palladium acetate-catalyzed decomposition of diazomethane cyclopropanates a,a- or a,jS-disubstituted a,jS-unsaturated carbonyl compounds in high yields (equation 47). The trisubstituted derivatives, however, do not react. The palladium acetate-catalyzed reaction has been applied also for the cyclopropanations of some strained cyclic alkenesstyrene derivatives and terminal double bondsHowever, the cyclopropanation of non-activated, internal double bonds occurs only with difficulty. The difference, thereby. 

This paper deals with the hydrothermal deactivation, under an air + 10 vol. % H2O mixture between 923 and 1173 K, of Cu-MFI solids, catalysts for the selective reduction of NO by propane. Fresh and aged solids were characterized by various techniques and compared with a parent H-ZSM-5 solid. The catalytic activities were measured in the absence and in the presence of water. The differences between fresh and aged Cu-ZSM-5 catalysts (destruction of the framework, extent of dealumination...) were shown to be small in spite of the strong decreases in activity. Cu-ZSM-5 is more resistant to dealumination than the parent H-ZSM-5 zeolite. The rate of NO reduction into N2 increases with the number of isolated Cu VCu ions. These isolated ions partially migrate to inaccessible sites upon hydrothermal treatments. At very high aging temperatures a part of the copper ions agglomerates into CuO particles accessible to CO, but these bulk oxides are inactive. Under catalytic conditions and in the presence of water, dealumination is observed at a lower temperature (873 K) than under the (air + 10 % H2O) mixture, because of nitric acid formation linked to NO2 which is either formed in the pipes of the apparatus or on the catalyst itself... 

Indeed, as the catalysis with copper is likely working through an intermediate cuprous alcoholate, the poor results obtained with the copper complexes are probably connected with the absence of alcoholates under the catalytic conditions used. 

Allylic acetoxylation with palladium(II) salts is well known however, no selective and catalytic conditions have been described for the transformation of an unsubstituted olefin. In the present system use 1s made of the ability of palladium acetate to give allylic functionalization (most probably via a palladium-ir-allyl complex) and to be easily regenerated by a co-oxidant (the combination of benzoquinone-manganese dioxide). In contrast to copper(II) chloride (CuClj) as a reoxidant,8 our catalyst combination is completely regioselective for allcyclic alkenes with aliphatic substrates, evidently, both allylic positions become substituted. As yet, no allylic oxidation reagent is able to distinguish between the two allylic positions in linear olefins this disadvantage is overcome when the allylic acetates are to... 

Under catalytic conditions, the reaction was independent of the alkyne concentration and second order with respect to Cu(I) (163). The first step in the suggested mechanism is the formation of a dinuclear copper complex, an intermediate species that reacts with the azide. 

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