Zinc foil

Zink-fahlerz, n. tennantite. -farbe, /. zinc paint, -feile,/., -feilspkne, m.pl. zinc fihngs. -folie, /. zinc foil, -formiat, n. zinc formate. 

Warm zinc powder incandesces in fluorine, and zinc foil ignites in cold chlorine if traces of moisture are present. 

Zinc foil reacts explosively when heated with anhydrous manganese dichloride. 

Preparation of the Zinc Amalgam. —Granulated zinc in thin pieces or, still better, zinc foil 0-15 to 0-25 mm. thick and cut into small strips, is left for one hour with frequent shaking in contact with an equal weight of 5 per cent aqueous mercuric chloride solution. The solution is then poured off and the metal washed once with fresh water. 

Leclanche (carbon—zinc) 1.5 zinc foil Mn02 (natural) aq ZnOL—NH4OI... 

Zinc is a whitish metal with a bluish hue. As an electropositive metal, it readily gives up its two outer electrons located in the N shell as it combines with nonmetal elements. Zinc foil will ignite in moist air, and zinc shavings and powder react violently with acids. Zinc s melting point is 419.58°C, its boiling point is 907°C, and its density is 7.14 g/cm. ... 

During the preparation of allylic zinc reagents, the formation of Wurtz-coupling products may be observed, especially if the intermediate allylic radical is well stabilized. However, the direct insertion of zinc foil to allyl bromide in THF at 5 C is one of the best methods for preparing an allylic anion equivalent. Allylic zinc reagents are more convenient to prepare and to handle than their magnesium and lithium counterparts... 

The nature of the zinc (dust, foil, or shots) is important for the success of the formation of an organozinc halide by oxidative addition. Usually, the use of zinc dust (-325 mesh) from Aldrich or Riedel de Haen gives the best results. In some cases, such as for the preparation of allylic zinc halide reagents,22,28 iodomethylzinc iodide,65 or benzylic zinc halides,66 the use of zinc foil (0.1 mm or 0.25 mm thick, Aldrich or Merck) may be advantageous or even essential. 

Alternatively, place a drop of the test solution (or a few milligrams of the test solid) in the reaction bulb of Fig. 11.56, add 2 thin pieces zinc foil and 2-3 drops dilute sulphuric acid. Place a small circle of quantitative filter paper (or drop-reaction paper) moistened with acetate-benzidine acetate reagent across the funnel. The paper is coloured blue by the hydrocyanic acid carried over with the hydrogen. 

OSHA PEL CL 5 mg(Mn)/m3 ACGIH TLV TWA 0.03 mg(Mn)/m3 SAFETY PROFILE Poison by intraperitoneal, subcutaneous, intramuscular, intravenous, and parenteral routes. Moderately toxic by ingestion. Experimental teratogenic and reproductive effects. Questionable carcinogen with experimental carcinogenic data. Mutation data reported. Explosive reaction when heated with zinc foil. Reacts violently with potassium or sodium. When heated to decomposition it emits toxic fumes of CT. See also MANGANESE COMPOUNDS and CHLORIDES. 

The best experimental conditions for the reaction have been discussed. An optimum temperature of 90-105° is easily maintained by the use of a refluxing mixture of benzene and toluene as solvent. Granulated zinc which has been washed with hydrochloric acid can be substituted for the sandpaper-cleaned zinc foil that is sometimes recommended. Magnesium has been used successfully for several condensa tions. ... 

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

Leclanche s cells have been around for more than 100 years. They are also known as zinc/carbon cells or dry cells. They use a chemically produced manganese dioxide cathode (positive electrode), a zinc (foil or sheet) anode (negative electrode), and an aqueous electrolyte. Typical electrolyte mixtures include ammonium chloride and zinc chloride dissolved in water. The electrodes are separated by a cereal paste wet with electrolyte or a starch or polymer-coated absorbent kraft paper. The reactions... 

For the synthesis of ethyl 2,4-dimethyl-3-hydroxyoctanoate from 2-methylhexanal and ethyl a-bromopropionate, Rinehart and Perkins used frt.shly sandpapered zinc foil which had been cut into narrow strips and rolled loosely. With a ratio of zinc ibromoester aldehyde of 3 3 1, the yield of hydroxy ester was 87% when the ratio was reduced to 2 3 1 the yield was owered to 68%. 

Rinehart also used sandpapered zinc foil for the reaction of n-capronitrile with iec-butyl a-bromopropionate to produce rec-butyl a-n-caproylpropionate, but added a catalytic amount of cupric bromide. The ratio of zinc bromo ester nitrile was... 

Dr. Rinehart replied to our query as follows I doubt that the cupric bromide had a great deal to do with the yield, and could be dispensed with sandpapering the zinc, however, it is a useful procedure for obtaining active zinc foil. ... 

Properties Shining white metal with bluish-gray luster (called spelter). Not found native. D 7.14, mp 419C, bp 907C, malleable at 100-150C, strongly electropositive, zinc foil will ignite in the presence of moisture. Soluble in acids and alkalies insoluble in water. 

Monoorganozinc halides (RZnX) can be synthesized by oxidative addition of organic halides to zinc metal. The oxidative addition rate is strongly affected by the reaction conditions (solvent, concentration) [16] and by activation of the zinc [15,17]. Zinc powder or zinc foil, which is activated by treatment with 1,2-dibromoethane and then with trimethylsilyl chloride, will oxidatively add alkyl iodides [18]. The reaction of alkyl bromides, on the other hand, requires more active zinc, which may be prepared by the reduction of zinc chloride with either lithium naphthalenide [19] or lithium metal under ultrasonic.irradiation [20, 21]. 

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