Molybdenum amalgam

Usually prepared by the action of NaCN on benzaldehyde in dilute alcohol. It is oxidized by nitric acid to benzil, and reduced by sodium amalgam to hydrobenzoin PhCHOHCHOHPh by tin amalgam and hydrochloric acid to des-oxybenzoin, PhCH2COPh and by zinc amalgam to stilbene PhCH = CHPh. It gives an oxime, phenylhydrazone and ethanoyl derivative. The a-oxime is used under the name cupron for the estimation of copper and molybdenum. 

The only metals having good or excellent resistance to corrosion by amalgamation with mercury are vanadium, iron, niobium, molybdenum, cesium, tantalum, and tungsten (8). The diffusion rates of some metals in mercury are given in Table 5. 

Reduction by homogeneous solutions containing molybdenum(III) and titanium(III) in methanol can be mediated by sodium amalgam. The reactions proceed at 20°C, and both hydrazine and ammonia are... 

Other Methods.—Electrolysis of a solution of molybdic acid in hydrochloric acid, using a mercury cathode, yields an amalgam, from which an active form of molybdenum is obtained on distillation. ... 

A hydrate of molybdenum trichloride has been stated to exist. By the action of potassium amalgam on a solution of molybdie acid in excess of hydrochloric acid, garnet-red, soluble prisms of the double... 

We found these conditions by introducing surface-active materials to a solution of a specially prepared catalytic complex containing molybdenum and stabilized by magnesium ions [22]. The structure of the complex which was isolated from the solution in its oxidized form is presented on Figure 5 [23]. When it is reduced to the Mo state the complex becomes an active catalyst of dinitrogen reduction to hydrazine and ammonia by sodium amalgam. Phospholipid (phosphatidylcholine)... 

The anion Mo(CO)3C5H5 has been prepared by the reaction of the cyclopentadienyl anion with molybdenum hexacarbonyF- and by the reaction of dicyclopentadiene mth molybdenum hexacarbonyl to form [CoH5Mo(CO)3]2, followed by reduction of the latter compound with sodium amalgam. In view of the simplicity of preparing cyclopentadienylpotassium (by deprotonation of cyclopentadiene with potassium hydroxide), the former method is preferable, and is described below. The Mo(CO)3C6H5 anion may be converted to the hydride HMo-... 

Cadmium amalgam has been studied as a reductant for perchlorate, with molybdenum as catalyst. The catalytic cycle involves Mo(V) and Mo(VI), in which a Mo(V) dimer is oxidized by C104. ... 

In case of mercury cells, especially heavy metal ions are precipitated galvanically at the mercury surface. In this case, parallel to the formation of sodium amalgam hydrogen gas will be evolved. The respective mechanism is discussed in detail in Sect. 5.2.3.6.1. So only traces of, for instance, vanadium, molybdenum, or cobalt are allowed in the brine (<0.01 ppm) [1],... 

The checkers analyzed for molybdenum by dissolving the sample in 5% H2S04 and reducing to Mo(III) in a Jones reductor (30-mesh zinc amalgam). The reduced solution was received directly in acidic iron(III) sulfate solution and was titrated with a standard cerium(IV) solution with ferroin as the indicator. 

A completely different system was developed by Shilov and coworkers (Didenko et al., 1983 and Russian references therein) they used a vessel containing sodium amalgam, apparently coated with the phospholipid phosphatidylcholine (lecithin). Molybdenum is added as M0CI5 to methanol as solvent. The results indicate that two Mo ions are involved in the reduction of each N2 molecule. The reaction pro-... 

Anionic carbonyl complexes of iron, ruthenium, chromium, molybdenum, tungsten, etc., also react with 3,4-dichlorocyclobutene or its derivatives. In order to obtain anionic derivatives, metal carbonyls are reduced by means of sodium amalgam [equations (8.29H8.31)]. 

The research of Shilov also seems to have real commercial potential. He has discovered several new systems, some of which are catalytic and function in protic solvents such as methanol. His most recent system uses sodium amalgam or electrochemical reduction of dinitrogen mediated by molybdenum, probably in the form of a molybdenum(III) complex. Phosphines enhance the reaction, and so does lethicin, which coats the amalgam surface. The reaction rate at room temperature and atmospheric pressure is greater than 0.3 mol N2 reduced per catalytic center per second, and the turnover number is several hundreds per molybdenum. " No firm conclusions have yet been drawn concerning the mechanism of dinitrogen reduction, though it is believed that polynuclear species are... 

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