Sodium amalgam reactions with

Keck demonstrated in 1995 that when the sodium amalgam reaction is run in MeOD as solvent, deuterium is incorporated into the product, in contrast to the absence of incorporation seen in the Sml2 reduction. Thus, the mechanism proposed above is completely consistent with the Sml2 reduction (M = Sml2). 

Sodium Amalgam. Cover with a large volume of water in a suitable vessel and allow to stand until there is no further reaction. The mercury may then be separated and recovered, and the sodium hydroxide solution washed into the drain.1... 

The treatment of the product of the sodium hydride or sodium amalgam reaction described above with liquid hydrogen chloride at low temperature produces an extremely unstable boron hydride which is shown to be octaborane(14) by elemental analysis and boron-11 nmr 223>. This new hydride decomposes quantitatively to octaborane(12) and hydrogen in minutes at room temperature. The structure proposed 223> on the basis of the boron-11 nmr spectrum violates the topological principles based on hydrogen atom crowding 141> and is thus consistent with this facile decomposition. 

The use of sodium amalgam originates with E. Fischer. The method was a cornerstone of his aldose homologation (cyanohydrin formation, hydrolysis, lactone formation and reduction) which was so important to the development of carbohydrate chemistry. Although the yields obtained by Fischer were moderate ca. 20-50%), more recent work by Sperber et al. has resulted in significant improvements. In particular, they discovered that control of the pH of the reaction mixture was very important. At pH 3-3.5, yields in the range 52-82% were obtained with a variety of aldonolactones. As an example, the preparation of arabinose is shown in equation (4). If the pH was allowed to rise, yields were lower due to overreduction. Methyl esters of aldonic acids could also be used as substrates. 

In the past 10 years other reductants of the C— Hg bond have been used, mainly thiols and sodium amalgam. Reduction with hydrogen sulfide, sodium dithionite, metals,alcohols, alkaline aqueous bases, aromatic amines, Wilkinson s catalyst and electrochemical reductions have also been described. Organomercurials react with thiols by free radical substitutions with an 5h2 mechanism (Scheme 34). The reaction between PhSH and A -hexenylmercury chloride initiated by light or AIBN gives a mixture of 1-hexene and methylcyclopentane. ... 

Sodium amalgam, 50, 50, 51 Sodium azide, 50,107 Sodium formate, reaction with acetyl chloride, 50, 1 Sommelet reaction, 50, 71 Styrene, reaction with carbethoxy-carbene, 50,94... 

Sodium amalgam reacts with water to form NaOH and H2. However, the rate of this reaction is very slow and is enhanced by coupling with graphite in a galvanic cell mode where the following component electrochemical reactions occur ... 

The catholyte from diaphragm cells typically analyzes as 9—12% NaOH and 14—16% NaCl. This ceUHquor is concentrated to 50% NaOH in a series of steps primarily involving three or four evaporators. Membrane cells, on the other hand, produce 30—35% NaOH which is evaporated in a single stage to produce 50% NaOH. Seventy percent caustic containing very Httie salt is made directiy in mercury cell production by reaction of the sodium amalgam from the electrolytic cells with water in denuders. 

The speed of the reaction depends both on the metal and on the alcohol, increasing as electropositivity iacreases and decreasiag with length and branching of the chain. Thus sodium reacts strongly with ethanol, but slowly with tertiary butyl alcohol. The reaction with alkaU metals is sometimes carried out ia ether, ben2ene, or xylene. Some processes use the metal amalgam or hydride iastead of the free metal. Alkaline earth metals and aluminum are often covered with an oxide film which hinders the reaction. 

Manufacture is either by reaction of molten sodium with methyl alcohol or by the reaction of methyl alcohol with sodium amalgam obtained from the electrolysis of brine in a Castner mercury cell (78). Both these methods produce a solution of sodium methylate in methanol and the product is offered in two forms a 30% solution in methanol, and a soHd, which is a dry, free-flowing white powder obtained by evaporating the methanol. The direct production of dry sodium methylate has been carried out by the introduction of methanol vapors to molten sodium in a heavy duty agitating reactor. The sohd is supphed in polyethylene bags contained in airtight dmms filled in a nitrogen atmosphere. 

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). 

Sodium ethoxide can also be prepared by the reaction of sodium amalgam with ethyl alcohol. 

Caustic soda by reaction of sodium amalgam and water Nitration of organic compounds with aqueous nitric acid Formation of soaps by action of aqueous alkahes on fats or fatty acids Sulfur removal from petroleum fractious by aqueous ethauolamiues Treating of petroleum products with sulfuric acid... 

Furylcarbinol has been prepared by the reduction of furfural with sodium amalgam but the Cannizzaro reaction is the better practical method of preparation. 

Reductive cleavages of carbon-chlorine bonds by active metals and with photochemical activation figure in recent studies aimed at HFCs and HCFCs Sodium amalgam [3J] (equation 25), zinc powder [34] (equation 26), and alumi-mun/tin chloride [35] (equation 26) are all used in conjunction with protic solvents in reactions giving high yields and conversions... 

Toluene from Toluidine.—It is often desirable to obtain tbe hydiocarbon from the base. The process of diazotisntion offers the only convenient method. The diazonium salt may be reduced by alcohol (Reaction 1, p. 162) or, as in the piesent instance, by sodium stannite. Less direct methods are the con-veision of the diazonium compound into (i) the hydrazine (see p. 174), (2) the acid and distillation with lime (p. 200), (3) the halogen derivative and reduction with sodium amalgam, 01, finally (4) the phenol and distillation with zinc dust. 

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