With zinc

Prepared by treating 1,3-dibromopropane with zinc. It is a powerful gaseous anaesthetic, non-irritant and non-toxic to the liver and kidneys, but it is a respiratory depressant. 

CH2CI2. A colourless liquid with a chloroform-like odour b.p. 4I°C. Prepared by heating chloroform with zinc, alcohol and hydrochloric acid manufactured by the direct chlorination of methane. Decomposed by water at 200°C to give methanoic and hydrochloric acids. Largely used as a solvent for polar and non-polar substances, particularly for paint removal (30%), dissolving cellulose acetate and degreasing (10%). It is more stable than carbon tetrachloride or chloroform especially towards moisture or alkali. It is somewhat toxic. U.S. production 1981 280000 tonnes. 

It is prepared commercially by treating benzene diazonium chloride with sodium sulphite and then reducing the mixture with zinc dust and ethanoic acid. It can also be prepared by reduction of benzene diazonium chloride with SnCl. ... 

Treatment with PCI5 gives phthalyl chloride reduction with zinc and ethanoic acid or NaOH gives phthalide. Fusion with urea gives phthalimide. 

Gases which are high in FIjS are subject to a de-sulphurisation process in which H2S is converted into elemental sulphur or a metal sulphide. There are a number of processes based on absorption in contactors, adsorption (to a surface) in molecular sieves or chemical reaction (e.g. with zinc oxide). 

For example,copper has relatively good corrosion resistance under non-oxidizing conditions. It can be alloyed with zinc to yield a stronger material (brass), but with lowered corrosion resistance. Flowever, by alloying copper with a passivating metal such as nickel, both mechanical and corrosion properties are improved. Another important alloy is steel, which is an alloy between iron (>50%) and other alloying elements such as carbon. 

If a solid sulphite is heated with zinc dust (or carbon) the sulphite is reduced to sulphide ... 

It catalyses the decomposition of potassium chlorate(V). Mixed with zinc oxide, it is used as a catalyst in the manufacture of methanol. It is used as a pigment, being very resistant to weathering. 

Because of its resistance to corrosion, zinc may be used to coat iron. This may be done by dipping the iron into molten zinc or by spraying zinc on the iron articles, for example iron sheets. This is known as galvanising. Smaller iron articles may be coated by heating with zinc dust, a process known as sherardising, or suspensions of zinc may be used in paints. 

Cadmium is usually found in zinc ores and is extracted from them along with zinc (p. 416) it may be separated from the zinc by distillation (cadmium is more volatile than zinc. Table 14.2) or by electrolytic deposition. 

The Reformatsky Reaction consists of the interaction of an ester of an a-halogeno-acid with an aldehyde, a ketone or another ester in the presence of zinc. For example, if a mixture of ethyl bromoacetate and benzaldehyde is heated with zinc, the latter undoubtedly first combines with the ethyl bromoacetate to form a Grignard-like reagent (reaction A), which then adds on to the benzaldehyde Just as a Grignard reagent would do (reaction B). The complex so formed, on acidification gives ethyl p-phenyl-p-hydroxy-propionate (reaction C). Note that reaction A could not satisfactorily be carried out using... 

The Fischer Indolisation Reaction occurs when the phenylhydrazone of a suitable aldehyde or ketone undergoes cyclisation with loss of ammonia, under the influence of various reagents, such as zinc chloride, ethnnolic hydrogen chloride, or acetic acid. For example, the phenylhydrazone of acetophenone (p. 257) when heated with zinc chloride gives 2 phenylindole. ... 

Further reduction in alkaline solution (say, with zinc powder) leads to azobenzene and hydrazobenzene ... 

Reduction of nitrobenzene in methyl or ethyl alcoholic sodium hydroxide solution with zinc powder leads to azobenzene or hydrazobenzene according to the proportion of zinc powder employed ... 

Experimental details are given for o-phenylenedlamlne, which is conveniently prepared by the reduction of o-nitroaniline in alcoholic sodium hydroxide solution with zinc powder ... 

Reduction of ketones, with zinc powder and alcoholic sodium hydroxide leads to secondary alcohols, for example ... 

One method of preparing sulphlnic acids has already been described (diazo reaction. Section IV,65). Reduction of a sulphonyl chloride with zinc powder and water affords the zinc salt of the sulphinic acid, converted by sodium carbonate to the sodium salt (in which form it is conveniently isolated), and by hydrochloric acid into the somewhat unstable sulphinic acid, for example ... 

Thiophenols (or aryl mercaptans) are obtained by more vigorous reduction of sulphonyl chlorides (or of sulphinic acids), for example with zinc and dilute sulphuric acid, and are isolated by steam distillation ... 

When pyridine is treated with zinc dust and acetic anhydride, a type of reductive coupling occurs and the product is diacetyltetrahydrodipyridyl (I) this undergoes a curious change on heating yielding pyridine and a new diacetyl compound, 1 4 diacetyl 1 4-dihydropyridine (II). The latter is reduced by zinc and acetic acid to 4-ethylpyridine (III). 

Reactor-grade zirconium is essentially free of hafnium. Zircaloy(R) is an important alloy developed specifically for nuclear applications. Zirconium is exceptionally resistant to corrosion by many common acids and alkalis, by sea water, and by other agents. Alloyed with zinc, zirconium becomes magnetic at temperatures below 35oK. 

Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained however, it is also found in iron, lead, and copper ores. 

Jote 2. We have also carried out this synthesis in ethanol as a solvent but the results were not reproducible. Although a series of experiments with zinc powder from one flask gave reasonable results (50-78% yields), a new flask with the same batch number gave low yields of impure products. The main impurity was probably the non-conjugated diene, H2C=CH-CH2-CH=CH-CH3, possibly resulting from reduction of the 1,2,4-triene by the zinc. The... 

C—C double bonds may be protected against electrophiles by epoxidation and subsequent removal of the oxygen atom by treatment with zinc and sodium iodide in acetic acid (J.A. Edwards, 1972 W. Kndll, 1975). Halogenation has often been used for protection, too. The C—C double bond is here also easily regenerated with zinc (see p. 138, D.H.R. Barton, 1976). 

Trichloro- and 2,2,2-tribromoethoxycarbonyl (Tceoc and Tbeoc) protecting groups are introduced with the commercially available 2,2,2-trihaloethyl chloroformates. These derivatives are stable towards CrOj and acids, but can smoothly be cleaved by reduction with zinc in acetic acid at 20 °C to yield 1,1-dihaloethene and CO. Several examples in lipid (F.R. Pfeiffer, 1968, 1970) and nucleotide syntheses (A.F. Cook, 1968) have been described. 

---