Amalgams mercury

The methylthio group is removed by treatment with zinc powder in HCl (276) to give the 2-unsubstituted thiazole. The action of aluminum-mercury amalgam in methanol on various thioethers is reported to yield the expected thiazole (108) when Rj is an alkyl group and the corresponding A-4-thiazoline-2-thione (109) when Rj PhCH - (Scheme 55) (169). 

The most commonly used method for reducing an aryl ketone to an alkylbenzene employs a zinc-mercury amalgam m concentrated hydrochloric acid and is called the Clemmensen reduction Zinc is the reducing agent... 

Silver-mercury amalgams [SILVER AND SILVER ALLOYS] (Vol 22)... 

Mercury amalgamates readily with gold and silver, and systems have been developed using these metals distributed on various carriers to remove mercury vapor from an akstream. When the system is saturated, the mercury can be removed easily and recovered by heating the unit and condensing the mercury. Other metals, such as copper and 2inc, can also be used. 

Dry-battery mercury anodes are pressed compacts of zinc—mercury amalgam. They were first developed and produced during World War II for walkie-talkie communica tion systems. Practically all hearing aids employ this type of battery in the 1990s. 

Strontium [7440-24-6] Sr, is in Group 2 (IIA) of the Periodic Table, between calcium and barium. These three elements are called alkaline-earth metals because the chemical properties of the oxides fall between the hydroxides of alkaU metals, ie, sodium and potassium, and the oxides of earth metals, ie, magnesium, aluminum, and iron. Strontium was identified in the 1790s (1). The metal was first produced in 1808 in the form of a mercury amalgam. A few grams of the metal was produced in 1860—1861 by electrolysis of strontium chloride [10476-85-4]. 

The word calcium is derived from calx, the Latin word for lime. The Romans used large quantities of calcium oxide or lime as mortar in constmction (see Lime and limestone). Because calcium compounds are very stable, elemental calcium was not produced until 1808 when a mercury amalgam resulted from electrolysis of calcium chloride in the presence of a mercury cathode. However, attempts to isolate the pure metal by distilling the mercury were only marginally successful. 

Recently it has been shown that the oxides of the platinum metals can have a higher corrosion resistance than the metals themselves , and have sufficient conductivity to be used as coatings for anodes, e.g. with titanium cores. Anodes with a coating of ruthenium dioxide are being developed for use in mercury cells for the electrolysis of brine to produce chlorine , since they are resistant to attack if in contact with the sodium-mercury amalgam. 

Another important primary battery is the mercury cell. It usually comes in very small sizes and is used in hearing aids, watches, cameras, and some calculators. The anode of this cell is a zinc-mercury amalgam the reacting species is zinc. The cathode is a plate made up of mercury(II) oxide, HgO. The electrolyte is a paste containing HgO and sodium or potassium hydroxide. The electrode reactions are... 

Alloys are metallic materials prepared by mixing two or more molten metals. They are used for many purposes, such as construction, and are central to the transportation and electronics industries. Some common alloys are listed in Table 5.5. In homogeneous alloys, atoms of the different elements are distributed uniformly. Examples include brass, bronze, and the coinage alloys. Heterogeneous alloys, such as tin-lead solder and the mercury amalgam sometimes used to fill teeth, consist of a mixture of crystalline phases with different compositions. 

Menten, M., 570 menthol, 782 mercury, Fl6, 669 mercury amalgam, 202 mercury cell, 525 mercury poisoning, 669 mesophase, 203 meta-, 742... 

Because of concerns about possible leaching of mercury from fillings, new resin materiab have replaced mercury amalgams as... 

Evaporation of mercury from mercury amalgam leaves pyrophoric chromium [1]. Increasing the temperature at which hexacarbonylchromium is thermally decomposed increases the surface area and pyrophoricity of the chromium powder produced [2],... 

Materials that are appropriate with respect to 2, 3 and 4 are gold, platinum, gold-mercury amalgam, silver and carbon. 

Gold-mercury amalgam appears to need a relatively high negative potential for reduction of oxygen and is therefore frequently used in reductive HPLC-EC. 

A similar experiment is performed with detector potential at —1.0 volt and a gold-mercury amalgam... 

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. 

The active part of the working electrode normally consists of a small disk or sphere of platinum (depending on whether one wishes to work under conditions of planar or radial diffusion). Alternatively, one can use gold, mercury (as a gold-mercury amalgam), or carbon. 

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]. 

Owing to the rocking of the box, the sodium mercury amalgam will pass into the centre compartment, where... 

Gallium makes a safe substitute for mercury amalgams in dental filhngs when it is combined with tin or silver. 

Martin, D. M., DeRouen, T. A. and Leroux, B. G. (1997). Is mercury amalgam safe for dental fillings Washington Public Health, 15(Fall), 30-32. MMWR. (1996a). Mercury exposure among residents of a building formerly used for industrial purposes - New Jersey, 1995. Morbidity Mortality Weekly Report, 45(20), 422-424- Online. Available HTTP (accessed 5 July 2003). 

---