Amalgams, as reducing agents

The process proposed by VCB, as well as ICf and Mitsui Toatsu, consists in using alkaline amalgams as reducing agents in a solvent such as formamide ... 

The metal is slowly oxidised by air at its boiling point, to give red mercury(II) oxide it is attacked by the halogens (which cannoi therefore be collected over mercury) and by nitric acid. (The reactivity of mercury towards acids is further considered on pp. 436, 438.) It forms amalgams—liquid or solid—with many other metals these find uses as reducing agents (for example with sodium, zinc) and as dental fillings (for example with silver, tin or copper). 

Environmental problems are often caused by the use of auxiliary materials, e.g. processes using Clemmensen reduction with amalgamated Zn as reducing agent [31, 35]. 

Sodium amalgam and elemental lithium have also been used as reducing agents in the preparation of [Ni(PPh3)2(CH2CCH2)]65 and [Ni(PPh3)2(PhCHCHPh)].154... 

While the demercuration of (3-acyloxymercurials has not received much attention, sodium borohydride or alkaline sodium borohydride have been most widely employed for this task. Hydrolysis to the corresponding alcohol or reversion to alkene are significant side reactions, however, and they are sensitive to the solvent used.4991500 Sodium amalgam and tri-n-butyltin hydride501 have also been utilized as reducing agents. 

Special success has followed the use of alkali metal amalgams in tetra-hydrofuran or other ethers (VII, 11, 44) as reducing agents in the syntheses of mono- and polynuclear metal carbonyls, e.g.,... 

Dissolving metals have been used as reducing agents in organic synthesis for well over a century and for many years metal-alcohol or metal amalgam-water systems were the principal methods employed for the reduction of aldehydes and ketones to primary and secondary alcohols, respectively. The same reagents were employed for the reduction of imines and oximes to the corresponding amines. Catalytic hy-... 

Prepare a chart showing oxidation states of Fe, Ti, V, and Cr formed when amalgams of Zn, Bi, Pb, and Hg are used as reducing agents in HCl solutions of appropriate concentrations. Show in principle how the four reductants could permit analysis of a sample containing Fe, Ti, V, and Cr. 

Enlarge the chart prepared in Problem 16-2 by adding the oxidation states of U, Mo, W, Cu and adding Cd amalgam and Ag as reducing agents. 

Instead of hydrogen sulphide, aluminium amalgam may be employed as reducing agent. 

Problem 34.8 As reducing agent, Fischer used sodium amalgam and acid. Today, lactones are reduced to aldoses by the addition of NaBH4 to an aqueous solution of lactone. If, however, lactone is added to the NaBH4, another product, not the aldose, is obtained.. What do you think this other product is Why is the order of mixing of reagents crucial ... 

Stannous chloride and tin amalgam have been used as reducing agents. 

Aluminum amalgam is also often used as reducing agent sodium amalgam is not recommended for reduction of aldehydes because of its basicity. 

Spcctrophotometric studies on technetium and rhenium were carried out with K4[b e(C N)f,], sulphosalicylic acid, and a-picolinic acid using pcrtechnetatc or perrhe-nate as starting compounds and bismuth amalgam, SnCl2 or ascorbic acid as reducing agents 78j. 

Generally, terminal-hydride complexes are prepared from metal halides, their phosphine derivatives, or organometallic complexes either by the action of a hydridometallate or dihydrogen in THF, alcohols, or other solvents. Potassium, sodium, sodium amalgam, and magnesium are also used as reducing agents. Some examples of preparative reactions are shown below... 

A reduction column using a Zn amalgam as a reducing agent. 

Jones reductor a reduction column using a Zn amalgam as a reducing agent, (p. 341)... 

Dithionites. Although the free-dithionous acid, H2S2O4, has never been isolated, the salts of the acid, in particular zinc [7779-86-4] and sodium dithionite [7775-14-6] have been prepared and are widely used as industrial reducing agents. The dithionite salts can be prepared by the reaction of sodium formate with sodium hydroxide and sulfur dioxide or by the reduction of sulfites, bisulfites, and sulfur dioxide with metallic substances such as zinc, iron, or zinc or sodium amalgams, or by electrolytic reduction (147). 

Hydrocinnamic Acid.—The preparation illustrates the use of sodium amalgam as a reducing agent It should be noted that hydiocinnamic acid may be also obtained from m.donic ester by acting upon the sodium compound nith benzyl chloride, then hydrolysing and removing carbon dioxide,... 

Conversely, sulfites can act as oxidants in the presence of strong reducing agents e.g. sodium amalgam yields dithionite, and formates (in being oxidized to oxalates) yield thiosulfate ... 

By application of the Clemmensen reduction,aldehydes and ketones 1 can be converted into the corresponding hydrocarbons 2. As the reducing agent zinc amalgam, together with concentrated hydrochloric acid or gaseous hydrogen chloride, is used. 

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