Hydrochloric acid with zinc

Another property shared by aqueous solutions of acids is that they react with many metals. All metals that are above hydrogen in the activity series react with acids to produce hydrogen gas. The reaction is caused by the hydronium ion present in the solution. The presence of the hydronium ion explains why all acids behave in this way. An example is the reaction of hydrochloric acid with zinc, which is shown in Figure 3 and is represented by the following net ionic equation. 

Reduction of the orange-red solution of thebaine in concentrated hydrochloric acid with zinc affords a yellow phenolic base about which little is yet known beyond the facts that it is dimolecular and contains no carbonyl group. Its ultra-violet absorption spectrum contains a band at about 3,800 A, apparently indicating the presence of a highly conjugated system of double bonds such as... 

The mixed amines are dissolved in hydrochloric acid and zinc chloride solution added. The quinoline chlorozincate, (C H7N)2,HtZnCl, crystallises out, being almost insoluble in water, while the aniline chlorozincate remains in solution. The quinoline chlorozincate is then filtered off and decomposed by alkalis, and the liberated quinoline extracted with ether or steam-distilled. 

Lucas reageut is prepared by dissolving 68 g. (0-5 mole) of anhydrous zinc chloride (fused sticks, powder, etc.) in 62 6 g. (0 6 mole) of concentrated hydrochloric acid with cooling to avoid loss of hydrogen chloride. 

Mesalamine. Rowasa, Asacol, and Pentasa are trade names for mesalamine [89-57-6] (5-ASA, 5-amino-2-hydroxybenzoic acid). It is a white to pinkish crystalline substance that is slightly soluble in cold water and alcohol, more soluble in hot water, and soluble in hydrochloric acid. It may be prepared by the reduction of y -nitrobenzoic acid with zinc dust and HCl. 

Anhydrous zinc chloride can be made from the reaction of the metal with chlorine or hydrogen chloride. It is usually made commercially by the reaction of aqueous hydrochloric acid with scrap zinc materials or roasted ore, ie, cmde zinc oxide. The solution is purified in various ways depending upon the impurities present. For example, iron and manganese precipitate after partial neutralization with zinc oxide or other alkah and oxidation with chlorine or sodium hypochlorite. Heavy metals are removed with zinc powder. The solution is concentrated by boiling, and hydrochloric acid is added to prevent the formation of basic chlorides. Zinc chloride is usually sold as a 47.4 wt % (sp gr 1.53) solution, but is also produced in soHd form by further evaporation until, upon cooling, an almost anhydrous salt crystallizes. The soHd is sometimes sold in fused form. 

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). 

Hydrogen is prepared in small amounts in the laboratory by reducing hydrogen ions from a strong acid (such as hydrochloric acid) with a metal that has a negative standard potential, such as zinc ... 

Purely aromatic ketones generally do not give satisfactory results pinacols and resinous products often predominate. The reduction of ketonic compounds of high molecular weight and very slight solubility is facilitated by the addition of a solvent, such as ethanol, acetic acid or dioxan, which is miscible with aqueous hydrochloric acid. With some carbonyl compounds, notably keto acids, poor yields are obtained even in the presence of ethanol, etc., and the difficulty has been ascribed to the formation of insoluble polymolecular reduction products, which coat the surface of the zinc. The adffition of a hydrocarbon solvent, such as toluene, is beneficial because it keeps most of the material out of contact with the zinc and the reduction occurs in the aqueous layer at such high dilution that polymolecular reactions are largdy inhibited (see Section IV,143). 

The hydroxyl groups of aldonolactones react with a variety of aldehydes and ketones to give the corresponding acetal derivatives. Treatment of the salts of aldonic acids with benzaldehyde and hydrochloric acid or zinc chloride as catalysts give benzylidene derivatives of aldonic acids or aldonolactones (3). 

A recently described approach involving zinc dust for eliminating acid allows acylation by 9-fluorenylmethoxycarbonyl chloride without dimer formation. The amino acid is dissolved in acetonitrile with the aid of hydrochloric acid, and zinc dust is added to destroy the acid and deprotonate the zwitter-ion, reducing the protons to gaseous hydrogen (Figure 3.16). Acylation is effected in the presence of zinc dust, which reduces the proton that is liberated by the reaction as soon it is formed. See Section 7.7 for another possible impurity in Fmoc amino acids.34,36-39... 

Various heterogeneous chemical reactions suggest themselves also as methods for securing fractionation of the two isotopes. Thus treatment of a large quantity of hydrochloric acid with iron or zinc should lead to a concentration of the H isotope in the undecomposed residual acid. 

A mixture of a solution of 0.300 g of an alkyl methanesulfonate or p-toluenesulfonate in 3-6 ml of 1,2-dimethoxyethane, 0.300 g of sodium iodide, 0.300 g of zinc dust, and 0.3 ml of water is stirred and refluxed for 4-5 hours. After dilution with ether the mixture is filtered the solution is washed with water, with 5% aqueous hydrochloric acid, with 5% aqueous solution of potassium hydrogen carbonate, with 5% aqueous solution of sodium thiosulfate and with water. After drying with anhydrous sodium sulfate the solution is evaporated and the residue worked up, giving 26-84% yield of alkane. 

In the first paper about oxadiazoles, published in 1884, Tiemann [114) mentioned that benzonitrile is formed when diphenyl oxadiazole is heated with hydrochloric acid and zinc dust. Until recently, no further information concerning the reduction of the oxadiazole ring was available. 

Pour 5 ml of a 1 W hydrochloric acid solution into a test tube and throw a small piece of zinc into it. When the evolution of hydrogen becomes quite vigorous, add 1-2 g of sodium acetate. Explain the change in the rate of hydrogen evolution. Write the molecular and net ionic equations of the chemical reaction of hydrochloric acid with sodium acetate. Does the activity of acetic acid decrease when dry sodium acetate is added to its solution ... 

Halogeno-l,2,4-thiadiazoles are destroyed fairly rapidly by zinc and hydrochloric acid, with evolution of hydrogen sulfide.88,91... 

First, we sincerely thank the authors who burned the midnight oil toiling over their research and book chapters. Writing book chapters is seldom an easy task, however much one is in love with the discipline, and one often has the mental feeling of the action of hydrochloric acid on zinc until the job is completed. We thank, too, those reviewers whose job is generally a thankless one at best. 

Chlorine. — Dilute 5 gm. of hydrochloric acid with 50 cc. of water and add zinc iodide-starch solution. The liquid must not develop a blue color within ten minutes. 

DROP ZINC STRIPS INTO A TEST TUBE. POUR IN A COUPLE OF ml HYDROCHLORIC ACID. THE ZINC DISPLACES THE HYDROGEN OF THE ACID TO FORM A SALT (ZnCI,) WITH THE CHLORINE. 

When the reactions of pyrroles and indoles with aldehydes are catalyzed by hydriodic acid, the initially formed carbinols or azafulvenes are reduced to yield the corresponding alkylpyrroles and alkylindoles (68CJC3291,70CJC139). The reductive alkylation of the pyrrole ring, using a range of aliphatic and aromatic aldehydes and ketones, may also be accomplished with phosphonium iodide, with hydrochloric acid and zinc amalgam, or with tin(II) bromide in hydrobromic acid. 

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