Mossy zinc

A 500-ml three-necked flask fitted with a mechanical stirrer and a nitrogen inlet and outlet is charged with 30 g (approx. 0.055 mole) of hydrated chromium (III) sulfate, 200 ml of distilled water, 7.5 g (0.12 g-atom) of mossy zinc, and 0.4 ml (5.4 g, 0.03 g-atom) of mercury. The flask is flushed with nitrogen for 30 minutes and a nitrogen atmosphere is maintained. The mixture is then heated to about 80° with stirring for 30 minutes to initiate reaction. Then the mixture is stirred at room temperature for an additional 30 hours, by which time the green mixture has been converted to a clear blue solution. Solutions prepared as above are about 0.55 M in chromium (II) and are indefinitely stable if protected from oxygen. 

The zinc-mercury amalgam used for reduction here and elsewhere can be prepared as follows. Add mossy zinc (powdered will probably do) to 1 % aqueous HgCl2, stir awhile, pour off the water and use the Zn-Hg residue for reduction. 

In a i-l. three-necked flask fitted with a stirrer (Note i) and a reflux condenser is placed 200 g. of amalgamated mossy zinc (Note 2). A mixture of 200 cc. of water and 200 cc. of concentrated hydrochloric acid is added and then a solution of 60 g. of o-heptanoyl phenol (Note 3) in 100 cc. of alcohol. The mixture is agitated vigorously and refluxed until reduction is complete (Note 4). 

Either Baker and Adamson or Mallinckrodt reagent grades of mossy zinc have been used interchangeably. 

Mossy zinc is activated by converting to zinc amalgam by brief immersion in amalgam solution. (Use 40 g mossy zinc immersed in 4 g mercuric chloride, 4 ml concentrated HCl acid, and 40 ml of water.) This type of amalgam can be used with powdered zinc also. 

Another Zinc Reduction. Prepare or activate the zinc as follows 400 g of mossy zinc is treated with 800 ml of 5% aqueous solution of mercuric chloride for 1 hour. Decant the solution off and use the zinc right away. Add. 834 mole of compound to be reduced to the zinc amalgam, followed by as much HCl acid (.834 mole) diluted in as much water as is required to cover all the zinc. Reflux for 6 hours while adding small portions of dilute HCL acid. Cool, separate the upper, wash free of acid (a few portions of dilute sodium hydroxide), dry and distill to get about a 79% yield of product. 

Zinc has been, and still is, after sodium the most abundantly used metal reductant. It is available mainly in form of zinc dust and in a granular form referred to as mossy zinc. 

In a one-liter flask fitted with a reflux condenser, 400 g (5,3 mol, 3.2 equivalent) of mossy zinc is treated with 800 ml of a 5% aqueous solution of mercuric chloride for 1 hour. The solution is decanted then 100 g (0.835 mol) of acetophenone is added followed by as much hydrochloric acid diluted with the same volume of water as is needed to cover all the zinc. The mixture is refluxed for 6 hours during which time additional dilute hydrochloric acid is added in small portions. After cooling the upper layer is separated, washed free of acid, dried and distilled to give 70g (79%) of ethylbenzene, b.p. 135-136°. 

Thioindoxyls are readily oxidized to thioindigo dyes.584 They may be reduced to benzo[6]thiophenes (Table XI) with zinc (Clemmensen reduction) or tin and acid (method a) (use of mossy zinc is preferred for the reduction of halothioindoxyls and also minimizes reduction of the thiophene ring),315 sodium borohydride (method b),222,424,432 or... 

A total of 150 g mossy zinc was amalgamated by treatment with a solution of 15 g mercuric chloride in 1 L H20. After swirling for 0.5 h, the H20 phase was... 

To 150 g mossy zinc there was added a solution of 3 g mercuric chloride in 60 mL H20, and this was swirled periodically for 2 h. The H20 was drained off, and the amalgamated zinc added to a 1 L three-neck round-bottomed flask, treated with 80 mL concentrated HC1, and heated on the steam bath. A solution of 20.8 g of 2,5-dimethoxybutyrophenone in 45 mL EtOH containing 10 mL concentrated HC1 was added in increments over a 4 h period. During this period an additional 140 mL of concentrated HC1 was added periodically to the ketone solution. 

Ammonium carbonate, (NH4)2C03 Potassium iodide, KI Potassium iodate, KI03 Calcium turnings, Ca Iron filings, Fe Mossy zinc, Zn Lead shot, Pb... 

The amalgamated zinc is prepared by adding ioo g. of mossy zinc to a solution of io g. of mercuric chloride in 200 cc. of water and shaking for one-half hour. The liquid is then poured off and the metal washed by decantation. 

A small sample of mossy zinc was placed into a reaction vessel, as shown in Figure 8.2. Hydrochloric acid was added, and the hydrogen gas that was generated was bubbled through water into a gas collection tube filled with water. When the reaction reached completion, the gas collection tube was nearly full. The gas was allowed to sit for several minutes. The collection tube was then adjusted so that the level of water in the tube was equal to the level of the water outside the tube. The volume of gas was determined to be 47 mL, and the temperature of the water was 22°C. The barometric pressure in the laboratory was 745 mm Hg. The vapor pressure of water at 22°C is 19.4 mm Hg. 

Several pieces of mossy zinc are added to hydrochloric acid in a filter flask fitted with a piece of rubber tubing. The rubber tubing is submerged under water so that the gas can be bubbled through the water and collected in a gas-collection tube. After a certain amount of hydrogen gas had been collected, the pressure in the gas-collection tube is 300 mm Hg and the temperature is 20.0°C. If the vapor pressure of water at this temperature is 18 mm Hg, what is the pressure of the hydrogen gas ... 

O To generate hydrogen gas, a student adds 5.77 g of mossy zinc to 80.1 mL of 4.00 mol/L hydrochloric acid in an Erlenmeyer flask. When the reaction is over, what is the concentration of aqueous zinc chloride... 

Amalgams. In effecling Clemmenscn-Marlin rcdiiclion of (l-benzoylpropionic acid to Y-phenylbutyric acid. Martin shook a mixture of 120 g, of mossy zinc, 12 g. of mercuric chloride, 20(1 ml. of WHter, and 5-6 ml. of concU. hydrochloric... 

Available forms Slab, rolled (strip, sheet, rod, tubing), wire, mossy zinc, zinc dust powder (99% pure), single crystals, zinc anodes. 

A mixture of mossy zinc (6 g) and 5% HgCl2 solution (12 mL) was kept at room temperature for 1 h with occasional shaking, and the aqueous layer was then decanted. The amalgamated zinc was covered with concentrated hydrochloric acid (30 mL) and water (20 mL), and the ketone (0.8 g, 2.2 mmol) and toluene (7 mL) were added. The mixture was heated under reflux for 2.5 h, cooled, and worked up to give 0.69 g of a crude mixture. The mixture was completely hydrolyzed by refluxing for 2 h with a solution of 0.5 g of potassium hydroxide in methanol (10 mL). The methanol was removed, and the residue was diluted with water. The clear alkaline solution was acidified and worked up to furnish 0.575 g of the crude phenol. The phenol was recrystallized from ether/petroleum ether to afford 0.51 g (76%) of the phenol. 

Preparation [1, 150]. In an improved procedure3 300 g. of hydrous chromium sulfate is mixed with 2 1. of water, 75 g. of mossy zinc, and 4 ml. of mercury and stirred in a stream of nitrogen and warmed for about 30 hrs. until the originally green solution is converted into a clear, deep sky blue. Filtration is thus eliminated. 

Some platinum is still present as hexachloroplatinate(IV) in the light yellow filtrate. It is recovered by strongly acidifying this solution with hydrochloric acid (pH about 1), adding excess mossy zinc, and allowing the mixture to stand until reduction appears complete (about one hour), with occasional stirring if necessary to remove precipitated platinum from the zinc and expose fresh metal surface. Additional acid is added, if necessary, to dissolve any excess zinc, and the platinum is collected on a Buchner funnel and washed and dried as was the previously recovered platinum. Since the metal produced by reduction with zinc is not as pure as that produced by ignition of ammonium hexachloroplati-nate(IV), the products should be kept separate. 

A) Oxidation states of transition elements. In four large test tubes place about 20 ml of dilute solutions of titanic chloride, ammonium metavanadate, potassium dichromate, and ammonium molybdate. Add to each about 10 ml of concentrated hydrochloric acid and several grams of granulated or mossy zinc. Set under the draft. Note all the color changes and interpret them by means of ionic equations. 

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