Amalgams reactions with

Despite its electrode potential (p. 98), very pure zinc has little or no reaction with dilute acids. If impurities are present, local electrochemical cells are set up (cf the rusting of iron. p. 398) and the zinc reacts readily evolving hydrogen. Amalgamation of zinc with mercury reduces the reactivity by giving uniformity to the surface. Very pure zinc reacts readily with dilute acids if previously coated with copper by adding copper(II) sulphate ... 

Aliphatic hydrocarbons can be prepared by the reduction of the readily accessible ketones with amalgamated zinc and concentrated hydrochloric acid (Clemmensen method of reduction). This procedure is particularly valuable for the prep>aration of hydrocarbons wdth an odd number of carbon atoms where the Wurtz reaction cannot be applied with the higher hydrocarbons some secondary alcohol is produced, which must be removed by repeated distillation from sodium. 

The speed of the reaction depends both on the metal and on the alcohol, increasing as electropositivity iacreases and decreasiag with length and branching of the chain. Thus sodium reacts strongly with ethanol, but slowly with tertiary butyl alcohol. The reaction with alkaU metals is sometimes carried out ia ether, ben2ene, or xylene. Some processes use the metal amalgam or hydride iastead of the free metal. Alkaline earth metals and aluminum are often covered with an oxide film which hinders the reaction. 

The potentiometric micro detection of all aminophenol isomers can be done by titration in two-phase chloroform-water medium (100), or by reaction with iodates or periodates, and the back-titration of excess unreacted compound using a silver amalgam and SCE electrode combination (101). Microamounts of 2-aminophenol can be detected by potentiometric titration with cupric ions using a copper-ion-selective electrode the 3- and... 

Clemmensen reaction is the reduction of carbonyl compounds with amalgamated zinc and concentrated hydrochloric acid... 

Lithium aluminum tn t butoxyhj dride in reduction of 3 acetoxy 5-pregnene 20 one, 46, 58 Lithium amalgam, reaction with 3,4-dichloro 1,2,3,4 tetramethylcy clobutene, 46, 36... 

Fluoroalkanephosphonic acid can be obtained by addition of iodine perfluoroalkane to vinylphosphonic acid dichloride followed by saponification and deiodination by sodium amalgam [141]. Fluoroalkanephosphonic acids can be transformed to fluoroalkanephosphonic acid glycil esters by 2 mol of epi-chlorhydrin in a water-free solution followed by reaction with alkalines or amines [142]. Compounds of this kind with an alkyl chain of 8-20 carbon at-... 

After separation of excess amalgam a solution of MXj is added. Reaction is rapid and the desired product can be separated from the Na halide or NaCN produced. If the separation of the amalgam is incomplete it is possible for Hg to be incorporated into the product (see 8.3.3.4). To avoid this, other methods of preparing carbonyl anions can be used, such as reaction with NaBH4, Na-K and other reducing agents ", or phase-transfer methods. ... 

Cis- and Pms-to-benzenesulfonylethene are also acetylene equivalents. The two sulfonyl groups undergo reductive elimination on reaction with sodium amalgam. 

Benzyne can also be generated from o-dihaloaromatics. Reaction with lithium amalgam or magnesium results in the formation of transient organometallic compounds that decompose with elimination of lithium halide. o-Fluorobromobenzene is the usual starting material in this procedure.126... 

This equation applies to all reversible electrode reactions with soluble ox and red, so it includes cathodic chronopotentiometry of ions of amalgamating metals such as Cd2+, Cu2+, Pb2+ and Zn2+ at stationary Hg electrodes. For a redox couple such as Fe3+/Fe2+ the diffusion coefficients DTeA and Dox will not differ much, so that Etl4 is approximately equal to E° (770 V). 

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... 

Interaction of sodium and mercury to form sodium amalgam is violently exothermic, and moderation of the reaction with an inert liquid, or by adding mercury slowly to the sodium is necessary. Even so, temperatures of 400°C may be attained. 

Lithium amalgam, reaction with 3,4-dichloro-1,2,3,4-tetramethylcy-clobutene, 46, 36... 

Elemental sulfur is present in most soils and sediments (especially anaerobic), and is sufficiently soluble in most common organic solvents that the extract should be treated to remove it prior to analysis by ECD-GC or GC-MS. The most effective methods available are (1) reaction with mercury or a mercury amalgam [466] to form mercury sulfide (2) reaction with copper to form copper sulfide or (3) reaction with sodium sulfite in tetrabutyl ammonium hydroxide (Jensen s reagent) [490]. Removal of sulfur with mercury or copper requires the metal surface to be clean and reactive. For small amounts of sulfur, it is possible to include the metal in a clean-up column. However, if the metal surface becomes covered with sulfide, the reaction will cease and it needs to be cleaned with dilute nitric acid. For larger amounts of sulfur, it is more effective to shake the extract with Jensen s reagent [478]. 

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