Aluminium Amalgams

By-products are formed in both preparations thus in the former, anthracene, and o- and p-dibenzylbenzenes are present in the fraction of high boiling point. Diphenylmethane is more conveniently obtained by the interaction of benzyl chloride and benzene in the presence of aluminium amalgam ... 

The aluminium amalgam is prepared as described in Section 11,50,72. After washing with water, it slioidd lir.st be washed with methyl alcohol and Anally with a little dry benzene. 

Other halogen carriers may be used, e.g., 1-2 g. of iron filings, or 1 g. of aluminium amalgam. The bromine must then be added slowly from a dropping funnel to the benzene warmed on a water bath the apparatu.s shown in Fig. II, 13, 9 is suitable and a trap for the hydrogen bromide must, however, be inserted into the top of the condenser. After all the bromine has been introduced, the mixture is heated on a water bath until no red vapours are visible above the liquid. The Subsequent procedure is as above. 

It is possible to reduce thiazole carbonyl derivatives with aluminium isopropoxide (56, 57). For example, 4-methyl-5-acetylthiazole gives 4-methyl-5-(a-hydroxyethyl)thiazole. With aluminium amalgam one obtains a duplication like to the pinacol reaction, and the yield is genaally poor... 

Condensation of pyndine with ketones in the presence of aluminium amalgam. 

Aluminium amalgam. Mainly used for removing traces of water from alcohols via refluxing followed by distillation. 

Other syntheses of tropic acid have been accomplished by Spiegel, Miiller, Wislicenus and Bilhiiber, Chambon and Natarajan and Swamina. ( > Of these, the most interesting is the reduction of ethyl formylphenylacetate (VIII) CHO. CHPh. COOC Hj in moist ethereal solution by aluminium amalgam to ethyl tropate, from which the acid (IX) HO. CHj. CHPh. COOH, is obtainable by hydrolysis with baryta. 

The (ZZ-ephedrine was resolved into its components by the use of d-and Z-mandelic acids. In 1921 Neuberg and Hirsch showed that benz-aldehyde was reduced by yeast, fermenting in suerose or glueose solution to benzyl aleohol and a phenylpropanolone, which proved to be Z-Ph. CHOH. CO. CH3. This ean be simultaneously, or consecutively, eondensed with methylamine and then eonverted to Z-ephedrine by reduction, e.g., with aluminium amalgam in moist ether, or by hydrogen in presenee of platinic oxide as catalyst (Knoll, Hildebrant and Klavehn ). 

The Knoevenagel method (Chapter T 20)was used to control the condensation of (36) to (35) and aluminium amalgam to remove the double bond from (35). 

Desulfurization of jS-ketosulfoxides with Zn/AcOH or aluminium amalgam - can lead to the corresponding ketones. Other related reactions may be those shown in Scheme... 

In the reaction of a-sulfonyl carbanion with lactones, the corresponding hydroxy-co-ketosulfones were obtained " . Thus, various o-hydroxyketones were shown by Umani-Ronchi and coworkers to be formed from the corresponding lactones. For example, the reaction of a, a-dilithioalkyl phenyl sulfones with lactones in THF at low temperatures afforded co-hydroxy-jS-ketosulfones which, upon desulfonylation with aluminium amalgam, gave the corresponding hydroxyketones . This process was applied for the syntheses of cis-jasmone and dihydrojasmone by treating y-valerolactone with ds-3-hexen-l-yl phenyl sulfone and n-hexyl phenyl sulfone. ... 

Pioneering work on the desulphonylation of jS-ketosulphones was carried out by Corey and Chaykovsky - . This reaction was part of a sequence which could be used in the synthesis of ketones, as shown in equation (53). The main thrust of this work was in the use of sulphoxides, but Corey did stress the merits of both sulphones and sulphonamides for different applications of this type of reaction. The method soon found application by Stetter and Hesse for the synthesis of 3-methyl-2,4-dioxa-adamantane , and by House and Larson in an ingenious synthesis of intermediates directed towards the gibberellin skeleton, and also for more standard applications . Other applications of the method have also been madealthough it does suffer from certain limitations in that further alkylation of an a-alkyl- -ketosulphone is a very sluggish, inefficient process. Kurth and O Brien have proposed an alternative, one-pot sequence of reactions (equation 54), carried out at — 78 to — 50°, with yields better than 50%. The major difference between the two routes is that the one-pot process uses the desulphonylation step to generate the enolate anion, whereas in the Corey-House procedure, the desulphonylation with aluminium amalgam is a separate, non-productive step. 

Naphtho[l,8-de][l,2,3]triazine 114 can be alkylated with a variety of alkyl halides and lithium diisopropylamide (LDA) to give alkylated derivatives 115. Reduction of 115 with aluminium amalgam cleaves the naphthotriazine moiety to afford substituted a-aminoacids 116 in good overall yields <00TL6665>. 

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. 

Individually indexed alloys or intermetallic compounds are Aluminium amalgam, 0051 Aluminium-copper-zinc alloy, 0050 Aluminium-lanthanum-nickel alloy, 0080 Aluminium-lithium alloy, 0052 Aluminium-magnesium alloy, 0053 Aluminium-nickel alloys, 0055 Aluminium-titanium alloys, 0056 Copper-zinc alloys, 4268 Ferromanganese, 4389 Ferrotitanium, 4391 Lanthanum-nickel alloy, 4678 Lead-tin alloys, 4883 Lead-zirconium alloys, 4884 Lithium-magnesium alloy, 4681 Lithium-tin alloys, 4682 Plutonium bismuthide, 0231 Potassium antimonide, 4673 Potassium-sodium alloy, 4646 Silicon-zirconium alloys, 4910... 

The formation of dimers by reduction of a,p-unsaturated ketones in aqueous media is well documented in the early literature of electrochemistry. Reductants include sodium or aluminium amalgams [58], dissolving zinc and a lead cathode in both acid and alkaline conditions [59,60]. Mixtures of dimers and dihydro derivatives were isolated. As the concept of the hydrodimerization of activated alkenes... 

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