Direct reaction with metals

These reactions are facilitated by the presence of spectator ligands such as phosphines and carbonyls. Phosphines, common co-ligands in organometallic compounds, are usually conveniently introduced through direct reaction with metal halides. 

I. Chelating Diene Complexes by Direct Reaction with Metal Complexes via Ligand Displacement. 

Another method of preparation involves the reaction with metal halides in the presence of a reducing agent (8.177). The nickel compound may also be prepared by ligand exchange as in (8.178) where the whole ligand is replaced. In certain cases direct reaction with metal salts can occur (8.179-8.181). 

Because they are weak acids or bases, the iadicators may affect the pH of the sample, especially ia the case of a poorly buffered solution. Variations in the ionic strength or solvent composition, or both, also can produce large uncertainties in pH measurements, presumably caused by changes in the equihbria of the indicator species. Specific chemical reactions also may occur between solutes in the sample and the indicator species to produce appreciable pH errors. Examples of such interferences include binding of the indicator forms by proteins and colloidal substances and direct reaction with sample components, eg, oxidising agents and heavy-metal ions. 

Pyrrohdinone forms alkaU metal salts by direct reaction with alkaU metals or their alkoxides or with their hydroxides under conditions in which the water of reaction is removed. The potassium salt prepared in situ serves as the catalyst for the vinylation of 2-pyrrohdinone in the commercial production of A/-vinylpyrrohdinone. The mercury salt has also been described, as have the N-bromo and N-chloro derivatives (61,62). 

Electron addition to BiqHh can be achieved by direct reaction with alkali metals in ethers, benzene or liquid NH3 ... 

Industrial use of HCl gas for the manufacture of inorganic chemicals includes the preparation of anhydrous NH4CI by direct reaction with NH3 and the synthesis of anhydrous metal chlorides by reaction with appropriate carbides, nitrides, oxides or even the free metals themselves, e,g, ... 

Oppenauer oxidation of the enol ether (34) affords the corresponding 17 ketone (37) (the enol ether is stable to the basic oxidation conditions). This ketone affords the corresponding 17a-ethynyl compound on reaction with metal acetylides. Hydrolysis of the enol ether under mild conditions leads directly... 

One of the most common chemical reducing agents for metallurgy is coke, a form of carbon made by heating coal at high temperature until all of the volatile impurities have been removed. Metals whose cations have moderately negative reduction potentials—Co, Ni, Fe, and Zn—are reduced by coke. For example, direct reaction with coke in a furnace frees nickel from its oxide NiO(.j) + C( ) Ni(/) -F CO(g)... 

Undoubtedly, the best method for the production of pure anhydrous lanthanide trihalides involves direct reaction of the elements. However, suitable reaction vessels, of molybdenum, tungsten, or tantalum, have to be employed silica containers result in oxohalides (27). Trichlorides have been produced by reacting metal with chlorine (28), methyl chloride (28), or hydrogen chloride (28-31). Of the tribromides, only that of scandium has been prepared by direct reaction with bromine (32). The triiodides have been prepared by reacting the metal with iodine (27, 29, 31, 33-41) or with ammonium iodide (42). 

Recently proof has been reported for a heterometallic bimolecular formation of aldehyde from a manganese hydride and acylrhodium species [2], Phosphine free, rhodium carbonyl species show the same kinetics as the cobalt system, i.e. the hydrogenolysis of the acyl-metal bond is rate-determining. Addition of hydridomanganese pentacarbonyl led to an increase of the rate of the hydroformylation reaction. The second termination reaction that takes place according to the kinetics under the reaction conditions (10-60 bar, 25 °C) is reaction (3). The direct reaction with H2 takes place as well, but it is slower on a molar basis than the manganese hydride reaction. 

A stable aluminum hydride, AlHj, has been known to exist since some time. It has been prepared by various techniques including the direct reaction of metallic A1 with atomic hydrogen by Siegel [105], AIH3 is soluble in ether when freshly synthesized but polymerizes while aged and forms insoluble precipitate whose structure depends on the degree of polymerization of -(AIH3)- monomer. 

Oppenauer oxidation of the enol ether (34) affords the corresponding 17 ketone (37) (the enol ether is stable to the basic oxidation conditions). This ketone affords the corresponding 17a-ethynyl compound on reaction with metal acetylides. Hydrolysis of the enol ether under mild conditions leads directly to ethynodrel (39), an orally active progestin. This is the progestational component of the first oral contraceptive to be offered for sale. Treatment of the ethynyl enol ether with strong acid leads to yet another oral progestin employed as a contraceptive, norethindrone (40). ° In practice these and all other so-called combination contraceptives are mixtures of 1-2% mestranol... 

This chapter deals with the methods of synthesis, characterization, and growth mechanisms of well-defined uniform particles of metal sufides and selenides formed by direct reaction of metal ions with the chalcogenide ions, released from thioacetamide or selenourea in dilute solutions, or supplied continuously from outside in the form of a high concentration of sulfide ions. 

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