Zinc dust amalgam

A related procedure utilizes zinc dust amalgam and HCl. Thus, several indoles are reduced to indolines in excellent yield (equation Somewhat similarly, the facile reduction of the indole double bond... 

Zinc dust, 36,14,19, 62 Zinc dust amalgam, 33,48 Zinc foil, preparation for Reformatsky reaction, 37, 38... 

In aqueous solutions trivalent protactinium is unknown. Tetravalent protactinium is stable in the absence of air, but it is rapidly oxidized to Pa(V) by oxygen. It can be prepared from Pa(V) by using strong reducing agents such as zinc dust, amalgamated zinc, or Cr(II) salts, or by electrolytic reduction. In moderately acidic (H <1 M) aqueous solutions Pa(IV) appears to exist as the protactinyl ion, PaO or Pa(OH)2, which forms moderately stable complexes [L2]. 

Aminoisoxazoles are obtained by reduction of 4-nitroisoxazoles with amalgamated aluminum, tin(II) chloride and hydrochloric acid, or zinc dust and acetic acid (62HC(17)1, p. 73). 

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. ... 

The synthesis of deoxybenzoin from phenacetyl chloride and benzene by the Friedel-Crafts reaction has been described. For symmetrically substituted deoxybenzoins, direct reduction of the readily accessible benzoin is a more convenient method. Reduction of benzoin by zinc dust and acetic acid, and by hydrochloric acid and granulated tin or amalgamated powdered tin has been reported. The present method is based on a publication of the authors. ... 

This, on reduction with zinc dust and acetic acid, yielded the corresponding oxime, which was further reduced by sodium amalgam to -3 4 5-trimethoxyphenylethylamine, CgHjj(OMe)3. CH. CH. NHg, and this proved to be identical with mezcaline (I). Like the latter, it behaves on analysis as if it contained the grouping —NHMe but this had already been disproved by Heffter. Interest in the remarkable physiological properties attributed to mezcaline has led to many syntheses of this alkaloid and of its isomerides and analogues. ... 

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. 

Benzohydrol has been obtained by reducing benzophenone with sodium amalgam,1 with metallic calcium and alcohol,2 with hydrogen in the presence of a catalyst,3 with zinc, aluminium or sodium in strongly alkaline solutions,4 with zinc dust and alcoholic potassium hydroxide solution,5 and electrolytically.6... 

An occasional batch of zinc dust failed to effect the desired reduction, possibly because of excessive oxide deposition on the surface of the zinc. It is suggested, therefore, that the surface of the zinc dust be cleaned with dilute hydrochloric acid just before amalgamation. 

An aluminium-mercury couple acts in the same way as zinc dust. This aluminium amalgam, prepared by the action of mercuric chloride on aluminium (preferably granulated), is also suitable for reducing substances dissolved in ether or alcohol the water which is required is slowly added drop by drop. (The method is that of H. Wislicenus.) The extent of the reduction varies according to the nitro-compound concerned, but corresponds approximately to the effect of zinc dust in a neutral medium. Consequently reduction usually does not proceed beyond the hydroxylamine stage. 

Toluenesulfinic acid and its salts have been prepared by three general methods (1) The reduction of the sulfonyl chloride. The reagents which have been used for this arc sodium amalgam,1 zinc dust in alcohol or water,2 sodium sulfite,3 sodium sulfide,4 potassium hydrosulfide 5 (the thio acid being first formed) and sodium arsenite.6 (2) From toluene by the Friedel and Crafts reaction, using either sulfur dioxide and hydrogen chloride 7 or sulfuryl chloride.8 (3) From -toluidine by diazotization and... 

Reduction of oximino esters, i.e. oximes of keto esters, is very useful for the preparation of amino esters. Reductions are very selective since the oximes are easily reduced by catalytic hydrogenation over 10% palladium on carbon in ethanol (yield 78-82%) I094, by aluminum amalgam in ether (yields 52-87%) [750, 70P5], or by zinc dust in acetic acid (yield 77-78%). None of these reagents attacks the ester group. The last mentioned reaction gives an N-acetyl derivative [1096. ... 

Cleavage of a-aminoketones and their quaternary ammonium salts by sodium amalgam or zinc dust and acid has been used in synthetic procedures. This process was a key step in determining the stereochemistry of the Stevens rearrangement for... 

According to E. Laurent,58 a soln. of sodium nitrate is decomposed in sunlight with the evolution of oxygen, while in darkness it is stable. Zinc dust reduces a soln. of potassium nitrate to the nitrite and hydroxide with the evolution of some oxygen above 60°, only a little nitrite but much nitrogen and ammonia are given off.59 The copper-zinc couple also reduces soln. of the nitrate, first to nitrite, and then to ammonia. Potassium amalgam, stannous chloride, etc., also reduce the nitrates in a similar way. 

Xanthydrol was first prepared by reducing xanthone by means of zinc dust in the presence of boiling alcoholic sodium hydroxide 1 it was later shown by Fosse that it could be conveniently prepared by the action of a low percentage sodium amalgam upon xanthone in alcohol. The method is based upon the directions of Fosse.2... 

The C-F bonds in l,l-difluoro-l,2-diphenylcthane (5) are resistant to several reducing agents the substrate is recovered unchanged after exposure to 2% sodium amalgam in ethanol or to zinc dust in refluxing ethanol and refluxing acetic acid. It is only partially converted into a mixture of 1,2-diphenylethane and ( )-l,2-diphenylethene with lithium aluminum hydride in refluxing dibutyl ether. On the other hand, catalytic reduction over palladium catalyst is completely successful.74... 

Although phenylhydroxylamine may be prepared by catalytic reduction,1 by the oxidation of aniline,2 and by electrolytic reduction of nitrobenzene,3 the most feasible method is still based upon the original zinc reduction method of Bamberger 4 and of Wohl.5 Various solvents and catalysts have been used in this reduction, and copper-coated and amalgamated zinc, as well as aluminium amalgam,6 have been substituted for zinc dust. The method herein recommended is essentially one previously described 7 but it has been found 8 that cooling is not an essential, as claimed in the patents. The preparation of the oxalate is also a more recent contribution.9... 

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