Sodium amalgam, preparation

REDUCTION WITH SODIUM AMALGAM Preparation of Sodium Amalgam [68]... 

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. 

Colourless crystals m.p. 122 C. It is prepared by reducing an alcoholic solution of xanthone with sodium amalgam. 

Sodium amalgam. The amalgam which is generally employed for reductions contains from 1 to 3 per cent, of sodium. Amalgams with a greater sodium content than 1 2 per cent, are solid at the ordinary temperature and can be powdered in a mortar the 1 2 per cent, amalgam is semi-solid at room temperature but is completely fluid at 50°. Two methods of preparation are available. 

If pure triphenylchloromethane and freshly prepared sodium amalgam are used, the yield of sodium triphenyl-methide should be almost quantitative but is usually 0 15 mol per htre (1). The reagent should be used as soon as possible after its preparation. 

The best results are obtained with freshly prepared xanthhydrol (reduction of xanthone with sodium amalgam. Section VII,16). Dissolve 0 -25 g. of xanthhydrol and 0 -25g. of the primary sulphonamide in 10 ml. of glacial acetic acid. Shake for 2-3 minutes at the laboratory temperature and allow to stand for 60-90 minutes. Filter oflf the derivative, recrystallise it from dioxan-water (3 1), and dry at room temperature under water pump suction for 30 minutes. 

Hydrocinnamic acid may also be prepared by the reduction of cinnamic acid with sodium and alcohol or with sodium amalgam or with hydrogen in the presence of Adams platinum oxide catalyst (Section 111,150) ... 

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. 

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

Heptyl alcohol has been prepared by the reduction of heptaldehyde with zinc dust and acetic acid,i with sodium amalgam and acetic acid, with sodium in toluene and acetic acid, and with hydrogen and a platinum catalyst. Heptaldehyde has also been reduced biochemically by adding it to a fermenting sugar solution. Heptyl alcohol has been prepared by the reduction of heptoamide with sodium and amyl alcohol. ... 

M-Hexyl alcohol has been prepared by the reduction of ethyl caproate by means of sodium and absolute alcohoB alone or in anhydrous ammonia solution by the reduction of -caproamide by means of sodium and absolute alcohol by the reduction of -caproaldehyde by means of sodium amalgam in dilute sulfuric acid and by means of living yeast, It has also been produced by the action of nitrous acid upon w-hexylamine by the action of sodium upon a mixture of ethyl alcohol and M-butyl alcohol ... 

The present procedure was developed from those of Wallach and Freylon, based upon the general method discovered by Leuckart. a-Phenylethylamine also can be prepared satisfactorily by the reduction of acetophenone oxime with sodium and absolute alcohol or sodium amalgam, but the reagents are more expensive and the processes less convenient. The amine has been obtained by reducing acetophenone oxime electro-lytically, by reducing acetophenone phenylhydrazone with sodium amalgam and acetic acid, from a-phenylethyl bromide and hexamethylenetetramine, and by the action of methyl-magnesium iodide upon hydrobenzamide, as well as by other methods of no preparative value. 

This procedure is an adaption of one described by Hauser and Chambers. Previous preparations include the benzylation of diethyl phenylmalonate followed by hydrolysis, the benzylation of phenylacetonitrile followed by hydrolysis, the benzylation of phenylacetic acid through the Ivanov reagent, and the reduction of oi-phenylcinnamic acid using sodium amalgam. ... 

EtOH) methiodide, m.p. 273°. To be distinguished from the better-known dihydrothebainol, m.p. 138-142°, [a] ° — 46-2°, prepared by reducing dihydrothebainone with sodium amalgam (Speyer and Siebert ). 

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,... 

Hydrogen can be prepared by the reaction of water or dilute acids on electropositive metals such as the alkali metals, alkaline earth metals, the metals of Groups 3, 4 and the lanthanoids. The reaction can be explosively violent. Convenient laboratory methods employ sodium amalgam or calcium with water, or zinc with hydrochloric acid. The reaction of aluminium or ferrosilicon with aqueous sodium hydroxide has also been used. For small-scale preparations the hydrolysis of metal hydrides is convenient, and this generates twice the amount of hydrogen as contained in the hydride, e.g. ... 

An enormous number of organomercury compounds are known. They are predominantly of the same stoichiometries as those of Zn and Cd, viz. RHgX and HgR2, and may be prepared by the action of sodium amalgam on RX ... 

Attempts to prepare this substance by reduction of dioxotetrahydro-1,3,5-triazine with sodium amalgam,hydroiodic acid, or tin in acetic acid, were accompanied by hydrolytic cleavage of the ring. Only... 

Further reduction of 3,4-dihydroquinazoline to l,2,3,Jt-tetTahydro-quinazoline is more difficult, but it can be accomplished with sodium amalgam or by catalytic reduction with palladium-charcoal. 1,2,3,4-Tetrahydroquinazolines have also been prepared by condensing o-aminobenzylamines with various aldehydes and with formaldehyde or methylenediamines (see 3b). 

Phenyl-propyl alcohol, CgH. CHj. CH.2. CHj. OH, is the next highest homologue of phenyl-ethyl alcohol, and is also known as hydro-cinnamyl alcohol. Like the last described bodies it has been known for many years, its first preparation being described in the Aivnalen (188, 202). It occurs as a cinnamic acid ester in storax, and as an acetic ester in cassia oil. It is prepared synthetically by the reduction of cinnamyl alcohol with sodium amalgam and water, or by the reduction of cinnamic or benzyl acetic esters with sodium and absolute alcohol. It has the following characters —... 

Preparation of y -Bis-(4-Hydroxylphenyl)-Hexane- i -Diol A sodium amalgam is prepared containing 6 grams of sodium and 400 grams of mercury. The amalgam is covered with a solution of 20 grams of 4-hydroxypropiophenone in a mixture of 30 ml of 5 N sodium... 

Reduction of 16-keto-17(0i)-hydroxyestratrienol-3-methyl to 16,17-dihydroxyestratrienol-3-methyl ether A solution of 800 mg of the alpha ketol methyl ether in 100 cc of ethanol and 10 cc of acetic acid was carefully maintained at 40°C (water bath), and 200 g of freshly prepared sodium amalgam (2%) were added in small pieces with efficient swirling. Before all of the amalgam had been added, a precipitation of sodium acetate occurred, and at this point an additional 100 cc of 50% acetic acid were added. After all the reducing agent had been added, the mixture was transferred to a separatory funnel with ether and water. 

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