Reduction with zinc powder

A further spectrophotometric method [3, 4] for water soluble boron in soil, boron is extracted from soil with boiling water. Borate in the extract is converted to fluoroborate by the action of orthophosphoric acid and sodium fluoride. The concentration of fluoroborate is measured spectrophotometrically as the blue complex formed with methylene blue and which is extracted into 1, 2-dichloroethane. Nitrates and nitrites interfere they are removed by reduction with zinc powder and orthophosphoric acid. 

Diaminodiphenyl derivatives can be obtained from appropriately substituted nitrobenzenes by a rather dated process of alkaline reduction with zinc powder/ sodium hydroxide solution, which affords hydrazobenzene. A more recent method uses a catalytic reduction process with hydrogen and specifically deactivated catalysts of precious metals. Subsequent acid-catalyzed rearrangement with hydrochloric acid yields the hydrochloride of the target diamine ... 

A( ueous solutions of chromium(ll) sulfate have Ijeen prepared from chromium(lll) sulfate by reduction with zinc powder and from potassium dichromate by reduction with amalgamated zinc and sulfuric acid. Solid chromitim(II) sulfate penlahyrlrate can be obtained from the reaction of highly purified chromium metal... 

Reduction with zinc powder and acid. Simple p-quinones are reduced to hydro-quinones in the following manner. Dissolve or suspend 0.5 g of the quinone in dilute hydrochloric acid (1 5) and add a little zinc powder. When the solution is colourless, filter, neutralise with sodium hydrogen carbonate, extract the dihyd-ric phenol with ether, remove the solvent and identify (Section 9.6.6, p. 1248). 

Reduction with zinc powder and sodium hydroxide. Compounds of the anthra-quinone type are reduced to oxanthrols. Treat 0.1 g of the quinone with dilute sodium hydroxide and zinc powder. Upon boiling the mixture a red colour is produced this disappears when the solution is shaken owing to aerial oxidation to the original quinone. 

Isobutyraldehyde is another reagent that has been applied to condensation with amino acids [261 ]. The reaction of methyl ester hydrochlorides of amino acids with isobutyraldehyde and sodium hydrogen sulphite proceeds in a solution of sodium carbonate according to Scheme 5.23. The azomethines produced were chromatographed either as such or as N.-alkyl esters after reduction with zinc powder in methanolic hydrogen chloride. N-Isobutylidene methyl esters of most of amino acids, except His, Arg, Trp,... 

This acid is not capable of existing in a free state, but may be obtained in form of its salts. The relationship between phthalophenone and triphenylmethane is easily determined. By treatment with alkalies it yields triphenylcarbinolcarbonic acid, and this may be converted to triphenylmethanecarbonic acid by reduction with zinc powder. On heating this latter compound, carbon dioxide splits off, forming triphenylmethane. 

Method 9 Destruction of cisplatin by reduction with zinc powder ... 

After a metal ion is selectively leached from an ore, it is precipitated from solution as the free metal or as an insoluble ionic compound. Gold, for example, is obtained from its cyanide complex by reduction with zinc powder ... 

Recently, Okamoto et al. reported that NHC-Fe species derived from FeCl2 or FeCla by in situ reduction with zinc powder in the presence of IMes or IPr were efficient catalysts for the intramolecular cyclotrimerisation of triynes into annulated benzenes (Equation (7.3)). Although no well-defined complex could be isolated from this mixture, its activity was preserved for a few days when kept under inert atmosphere. 

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