Arsenate displacement

With pressures up to 150 atm. the quantity of arsenic displaced by hydrogen from solutions of arsenic trichloride in hydrochloric acid is proportional to the pressure. Between 15 and 250 atm., and with solutions not exceeding normal concentration, the reaction is one of the... 

Optional experiment. When all the air has been displaced, collect a test-tube of the gas over water (by appropriate inclination of the end of the delivery tube beneath the mouth of a test-tube filled with water and supported in a beaker of water). Observe the colour and odour of the gas. Ignite the test-tube of gas, and note the luminosity of the flame and the amount of carbon deposited. Pure acetylene is almost odourless the characteristic odour observed is due to traces of hydrides of phosphorus, arsenic and sulphur. 

Acetylated aniline 21 was reacted under Skraup/Doebner-von Miller conditions in the presence of an arsenic salt to yield quinoline 22 with concurrent displacement of fluorine. ... 

Treat the arsenate solution (say, 20.0 mL of ca 0.025M) in a glass-stoppered conical flask with concentrated hydrochloric acid to give a solution in 4M hydrochloric acid. Displace the air by introducing two 0.4 g portions of pure sodium hydrogencarbonate into the flask. Add 1.0 g of pure potassium iodide, replace the stopper, mix the solution, and allow to stand for at least 5 minutes. Titrate the solution, whilst stirring vigorously, with standard 0.1M sodium thiosulphate. 

Gold ores can be concentrated by froth flotation, the resulting concentrate being roasted at 600-800°C to oxidize off sulphur and arsenic as their oxides. The product is extracted with cyanide under oxidizing conditions (using either peroxide or air itself) before displacement with powdered zinc. More reactive metals (silver etc.) can be removed by chlorination of molten gold. 

Asl3 and Bils. Heyworth and Braekken4) in their studies of the hexagonal crystals Asls and Bils assigned to them structures in which each arsenic or bismuth atom is surrounded by six equidistant iodine atoms, the interatomic distances reported being As—I = 2.97 A and Bi—I = 3.09 A. As in the case of eulytite, we believe that the trivalent atoms are displaced towards three and away from three of these six atoms, until the smallest interatomic distances become As — 7 = 2.54 A and Bi — I = 2.84 A5). 

On the surface of metal electrodes, one also hnds almost always some kind or other of adsorbed oxygen or phase oxide layer produced by interaction with the surrounding air (air-oxidized electrodes). The adsorption of foreign matter on an electrode surface as a rule leads to a lower catalytic activity. In some cases this effect may be very pronounced. For instance, the adsorption of mercury ions, arsenic compounds, or carbon monoxide on platinum electrodes leads to a strong decrease (and sometimes total suppression) of their catalytic activity toward many reactions. These substances then are spoken of as catalyst poisons. The reasons for retardation of a reaction by such poisons most often reside in an adsorptive displacement of the reaction components from the electrode surface by adsorption of the foreign species. 

Dimercaprol (British Anti-Lewisite or BAL) is a colorless, viscous oily compound with an offensive odor used in treating arsenic, mercury, and gold poisoning. It displaces the arsenic bound to enzymes. The enzymes are reactivated and can resume their normal biological activity. When given by injection, BAL can lead to alarming reactions that seem to pass in a few hours. 

Liquid MD penetrates skin on contact. Prolonged skin exposure to its arsenic component will lead to systemic damage through bone calcium displacement and subsequent bone marrow destruction. In its traditional form, MD quickly disperses in open terrain but presents a more prolonged hazard in tightly closed buildings, where it concentrates in basements and substructures due to its vapor density.1... 

Pyridyl-phosphorus and -arsenic compounds have also been made by nucleophilic displacement reactions with, for example, 3-pyridinediazonium salts (74HC(14-2)489). Organomercury derivatives can be converted into bromides and iodides by standard methods, e.g. Scheme 147 (59JPR(8)156). 

The corresponding palladium compound (157) must be formulated as [Pd(TA)Br]+Br. The cation is essentially square-planar, but the bromine atom is displaced 10° out of the arsenic-palladium plane. Such a distortion is very unusual for palladium, and may be due to a steric effect of the alkyl chains in the arsine ligand. This might similarly account for the distortion of the nickel complex from a square pyramidal shape. 

Water Displacing Oil Water Glass Waxes Camauba Waxes Paraffin Weisspiessglanz White Arsenic White Oil White Vitriol Witcizer 300 Witcizer 312 Wood Alcohol Wood Charcoal Wood Ether Wood Naphtha Wood Spirit Wood Turpentine Meta-Xylene P-Xylene O-Xylene M-Xylene... 

The toxic forms of arsenic are mainly (Section III,A) compounds of the type R—AsX2, where X is a ligand that is easily displaced by thiols. Many such compounds are volatile, and this increases their hazard. As mentioned in Section VII,A,2, one such compound, Cl2As— CH2—AsC12, is a convenient intermediate in the synthesis of the diphosphate analogue H203As—CH2—As03H2. Obviously, its distillation and that of any similar compound should be performed in a fume... 

In the latter, the valency angles must be about 100°, so the layers cannot be flat. Their shape is obtained if, in Figure 38, the atoms shown with the clear circles are displaced somewhat below the plane of the paper and the shaded ones similarly, above it. If the layers formed in this way are then arranged on top of one another, the crystal structure of the elements arsenic, antimony and bismuth are obtained in their normal forms in which they have metallic properties. There also exists a modification of phosphorus with a similar structure. In addition, there are other forms of arsenic and antimony, the properties of which correspond to those of yellow phosphorus these forms contain molecules p As4 and Sb4. 

Arsenic does not combine directly with molecular hydrogen,9 and the element may be purified by sublimation in that gas. Hydrides, however, may be obtained by indirect methods (see pp. 79-84). Arsenic may be displaced by the gas from solutions of its salts at high temperatures and pressures. Thus arsenic separates in large well-defined crystals when a solution of sodium arsenate is subjected to the action of hydrogen at 25 atm. pressure 10 the action commences at 300° C., 15 per cent, of the arsenic being precipitated at this temperature, but it increases rapidly with rising temperature and at 350° C. 77 per cent, of the arsenic is liberated. Arsine is not produced in the reaction. 

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