Zinc acetate amalgam

Intramolecular cycloaddition of jV-(cycloalkenyl)nitrones has also been extensively investigated. Thus, stepwise oxidation of the amine (35) and cyclization of the ensuing nitrone provided isoxazolidine (36) in 64% overall yield as the only observed regioisomer (Scheme 8).16 Isoxazolidine (36) was then desul-fonated with buffered sodium amalgam and further reduced with zinc-acetic acid to provide the corresponding y-amino alcohol subsequent dehydration provided (-)-hobartine. 

Cyclic Peroxides. CycHc diperoxides (4) and triperoxides (5) are soHds and the low molecular weight compounds are shock-sensitive and explosive (151). The melting points of some characteristic compounds of this type are given in Table 5. They can be reduced to carbonyl compounds and alcohols with zinc and alkaH, zinc and acetic acid, aluminum amalgam, Grignard reagents, and warm acidified iodides (44,122). They are more difficult to analyze by titration with acidified iodides than the acycHc peroxides and have been sucessfuUy analyzed by gas chromatography (112). 

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. ... 

Benzopinacol has been prepared by the action of phenylmag-nesium bromide on benzil 1 or methyl benzilate. Usually it has been obtained by reduction of benzophenone, the reducing agents being zinc and sulfuric acid or acetic acid, aluminum amalgam, and magnesium and magnesium iodide. The present... 

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. ... 

Note 2. The use of amalgamated zinc and alcohol has been recommended instead of zinc and acetic acid. Higher yields and better reproducibility are claimed. ... 

Reaction of p-fluorobenzyl chloride with the anion of diethylmethylmalonate ester followed by saponification and decarboxylation leads to acid 9. Polyphosphoric acid cyclization leads to indanone 10. A Reformatsky reaction with zinc amalgam and bromo-acetic ester leads to carbinol 11 which is then... 

Amalgamated zinc residues isolated from Clemmensen reduction of an alkyl aryl ketone in glacial acetic acid were pyrophoric, and had to be immediately dumped into water after filtration to prevent ignition. 

N-Methylethylamine has been prepared by heating ethyl-amine with methyl iodide in alcohol at 100° 3 by the hydrolysis of N-methyl-N-ethylarenesulfonamides,4-5 -nitroso-N-methyl-N-ethylaniline,6 or methylethylbenzhydrylidene ammonium iodide 7 by catalytic hydrogenation of ethyl isocyanate or ethyl isocyanide 8 and by the reduction of ethyl isocyanate by lithium aluminum hydride,9 of N-methylacetisoaldoxime by sodium amalgam and acetic acid,10 or of a nitromethane/ethylmagnesium bromide adduct by zinc and hydrochloric acid.11... 

The neutralization values were influenced by reduction with strong reducing agents, lithium aluminum hydride, sodium borohydride, and amalgamated zinc plus hydrochloric acid (35, 46). For the most part, the consumption of NajCOj and of NaOEt decreased in equivalent amounts. This is further confirmation of the assumption that lactones of the fluorescein type or of the lactol type are present. The reaction with sodium ethoxide was shown to be no true neutralization, that is, exchange of H+for Na+, at all, but an addition reaction w ith the formation of the sodium salt of a semi-acetal or ketal ... 

Reduction of a,/3-unsaturated to saturated ketones was further achieved by electrolysis in a neutral medium using copper or lead cathodes (yields 55-75%) [766], with lithium in propylamine (yields 40-65%) [876], with potassium-graphite clathrate CgK (yields 57-85%) [807], and with zinc in acetic acid (yield 87%) [688]. Reduction with amalgamated zinc in hydrochloric acid (Clemmensen reduction) usually reduces both functions [877]. 

Acyloins were converted to mixtures of stereoisomeric vicinal diols by catalytic hydrogenation over copper chromite [972]. More frequently they were reduced to ketones by zinc (yield 77%) [913, 914], by zinc amalgam (yields 50-60%) [975], by tin (yields 86-92%) [173], or by hydriodic acid by refluxing with 47% hydriodic acid in glacial acetic acid (yields 70-90%) [916], or by treatment with red phosphorus and iodine in carbon disulfide at room temperature (yields 80-90%) [917] Procedure 41, p. 215). Since acyloins are readily accessible by reductive condensation of esters (p. 152) the above reductions provide a very good route to ketones and the best route to macro-cyclic ketones [973]. 

Refluxing with zinc in ethanol reduced a-bromocinnamic acid to cinnamic acid in 80% yield [997]. Allylic chlorines in y,y,y-trichlorocrotonic acid were partly or completely hydrogenolyzed by zinc and sodium amalgam [5/9]. Hydrogenolysis of allylic bromine in oc, -unsaturated esters with zinc in acetic acid gave predominantly, y-unsaturated esters in 65-97% yields [998]. 

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. ... 

Vinyl acetate is one of many compounds where classical organic chemistry has been replaced by a catalytic process. It is also an example of older acetylene chemistry becoming outdated by newer processes involving other basic organic building blocks. Up to 1975 the preferred manufacture of this important monomer was based on the addition of acetic acid to the triple bond of acetylene using zinc amalgam as the catalyst, a universal reaction of alkynes. 

Bicyclo[4.2.0]octanes wiLh carbonyl groups adjacent to each bridgehead carbon cleave the central bond on reduction with lithium in liquid ammonia,158,159 with sodium/potassium alloy in the presence of chlorotrimethylsilane,160 with zinc in acetic acid,37 or with zinc amalgam in hydrochloric acid.15 7... 

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