Arsenious oxide

Required Arsenious oxide, 27 g. aniline, 20 ml. (20 g.) anhydrous sodium carbonate, 55 g. crystalline copper sulphate,... 

Add in turn 55 g. of anhydrous sodium carbonate, 27 g. of powdered arsenious oxide and i g. of hydrated copper sulphate to 175 ml. of water in a 2 litre beaker, and heat the stirred mixture until an almost clear solution is obtained then immerse the stirred solution in ice-water, and cool it to 5°. 

In a 1-litre three-necked flask, mounted on a steam bath and provided respectively with a separatory funnel, mechanical stirrer and double surface condenser, place 165 g. of bromoform (96 per cent.). Add 10 ml. of a solution of sodium arsenite made by dissolving 77 g. of A.R. arsenious oxide and 148 g. of A.R. sodium hydroxide in 475 ml. of water. Warm the mixture gently to start the reaction, and introduce the remainder of the sodium arsenite solution during 30-45 minutes at such a rate that the mixture refluxes gently. Subsequently heat the flask on the steam bath for 3-4 hours. Steam distil the reaction mixture (Fig. 11, 41, 1) and separate the lower layer of methylene bromide (79 g.). Extract the aqueous layer with about 100 ml. of ether a further 3 g. of methylene bromide is obtained. Dry with 3-4 g. of anhydrous calcium chloride, and distil from a Claisen flask with fractionating side arm. The methylene bromide boils constantly at 96-97° and is almost colourless. 

In a 1-litre three-necked flask, fitted with a mechanical stirrer, reflux condenser and a thermometer, place 200 g. of iodoform and half of a sodium arsenite solution, prepared from 54-5 g. of A.R. arsenious oxide, 107 g. of A.R. sodium hydroxide and 520 ml. of water. Start the stirrer and heat the flask until the thermometer reads 60-65° maintain the mixture at this temperature during the whole reaction (1). Run in the remainder of the sodium arsenite solution during the course of 15 minutes, and keep the reaction mixture at 60-65° for 1 hour in order to complete the reaction. AUow to cool to about 40-45° (2) and filter with suction from the small amount of solid impurities. Separate the lower layer from the filtrate, dry it with anhydrous calcium chloride, and distil the crude methylene iodide (131 g. this crude product is satisfactory for most purposes) under diminished pressure. Practically all passes over as a light straw-coloured (sometimes brown) liquid at 80°/25 mm. it melts at 6°. Some of the colour may be removed by shaking with silver powder. The small dark residue in the flask solidifies on cooling. 

Concurrently with the preparation of the phenyldiazonium chloride solution, prepare a cold suspension of sodium arsenite. Place 250 ml. of water in a 3-htre round-bottomed flask equipped with a mechanical stirrer. Heat the water to boding, add 125 g. of anhydrous sodium carbonate, and, as soon as the carbonate has dissolved, introduce 62 5 g. of pure arsenious oxide and 3 g. of crystallised copper sulphate with stirring. When all the solids have dissolved, cool the solution with stirring under a stream of tap water until the temperature has fallen to 15°. 

Alternatively, prepare the sodium meta-arsenite solution by dissolving 39 6 g. A.R. arsenious oxide and 32 g. of A.R. sodium hydroxide in 600 ml. of water. 

Arsenious oxide, trivalent antimony (73), sulfurous acid (74), hydrogen sulfide (75), stannous ion, and thiocianate (76) have been recommended for the titration of iodine. However, none of these appears to have a greater sensitivity for the deterrnination of minute quantities of iodine than thiosulfate. Organic compounds such as formaldehyde (77), chloral hydrate (78), aldoses (79), acetone (70,80), and hydroquinone have also been suggested for this purpose. 

The demand for metallic arsenic is limited and thus arsenic is usually marketed in the form of the trioxide, referred to as white arsenic, arsenious oxide, arsenious acid anhydride, and also by the generally accepted misnomer arsenic. 

Arsenic III oxide (arsenic trioxide, arsenious oxide) [1327-53-3] M 197.8, three forms m 200°(amorphous glass), m 275°(sealed tube, octahedral, common form, sublimes > 125° without fusion but melts under pressure), m 312°, pKj 9.27, pK 13.54, pK 13.99 (for H3ASO3). Crystd in octahedral form from H2O or from dil HCl (1 2), washed, dried and sublimed (193°/760mm). Analytical reagent grade material is suitable for use as an analytical standard after it has been dried by heating at 105° for l-2h or has been left in a desiccator for several hours over cone H2SO4. POISONOUS (particulary the vapour, handle in a ventilated fume cupboard). 

Heat a very small quantity of potassium acetate with an equal bulk of arsenious oxide. The disagreeable and poisonous vapour of cacodyl oxide is evolved. 

Vetrocoke process aqueous potassium carbonate-arsenious oxide as Benfield, also As203 is poison—about 50% of activity is lost when As = 0.5%... 

Arsenic Trtoxide (Arsenous Acid, Arsenous Acid Anhydride, Arsenious Oxide, Arsenic Sesqui-oxide, White Arsenic). As203, mw 197.82 ... 

The reaction between arsenious oxide and concentrated nitric acid yields a mixture of nitric oxide and nitrogen dioxide. It also contains some nitrogen tetroxidc and perhaps trioxide, the amount in equilibrium depending upon the temperature of the gas. The compressed air forced in via flask A insures an excess of oxygen, and thus complete oxidation. Only a slow stream is necessary, two to three bubbles per second. 

Before finally assembling the apparatus, the various units are charged as follows A is one-third filled with water to serve as a bubble counter. Generator B is about one-quarter filled with dry arsenious oxide, pea size or powdered. Drying towers G and H are filled with anhydrous calcium chloride. (It is well to place a wad of glass wool in front of the entrance and exit tubes.) In each of the two absorption bottles J and K is placed 200 g. of ethyl malonate. Dish L is filled with an ice-salt freezing mixture. 

Lidov A process for chlorinating cyclopentadiene to octachloropentadiene, which is then thermally dechlorinated to hexachlorocyclopentadiene (HCCP), used as an intermediate in the manufacture of insecticides and flame retardants. The initial chlorination is catalyzed by phosphoms pentachloride or arsenious oxide. Invented by R. E. Lidov in The Netherlands and commercialized by the Shell Chemical Company. 

Pseudonitrosites can sometime be isolated and converted into furoxans by heating in alcohol or water. In some cases the reaction is carried out with a mixture of nitrogen oxides for example, 4-nitro-3-phenylfuroxan is obtained by the action on cinnamaldehyde of nitrogen oxides generated by a mixture of nitric and arsenious oxides [9],... 

When nitrous gases (from arsenious oxide and nitric acid, d. 1 -35) are passed into a well-cooled suspension of aniline nitrate in water, and alcohol and ether are then added gradually, crystalline phenyldiazonium nitrate is obtained. At most only 2 g. of aniline are used, and of the diazonium salt only as much as covers well the tip of a knife-blade is dried on porous plate, after collecting at the pump and washing with alcohol-ether (1 1). 

Prepared by dissolving 23-5 g. of powdered arsenious oxide in 240 c.o. of previously titrated 2 jV-sodium hydroxide solution and diluting to 800 o.o. 

Organochlorine or -bromine compounds are burned in the presence of aqueous solutions of arsenious oxide (AS2O3) or hydrazine hydrochloride (N2H4.2HCI). These solutions are effective in reducing the elemental chlorine or bromine formed to the chloride or bromide ions according to the reactions (X = Cl, Br) [61,62,64-66] ... 

With Arsenic —Hydrogen does not directly combine with arsenic, but if an arsenic compound is in solution in a liquid in which hydrogen is being generated, i.e. hydrogen in the nascent state, chemical union takes place. Thus, if arsenious oxide is dissolved in dilute hydrochloric acid and a piece of metallic zinc is added, the hydrogen produced by the action of the add on the zinc will combine with the arsenic, in accordance with the following equation —... 

History. For centuries man has recognized that rodent pests destroy his habitat, consume his food, and cause the spread of virulent diseases. Throughout the same centuries man has sought to eliminate these pests with a variety of poisons such as strychnine, arsenious oxide, and red squill - a steroidal glycoside extracted from the bulb of a lily-like plant, Urginea maritima. 

In the same way a mixture of arsenious oxide and potassium fluoride, yields potassium hexafluoroarsenate, a product which can be explained only by postulating the acid BrFgAsFg as an intermediate. 

Arsenic pentoxide is prepared by dehydration of crystalline arsenic acid at 200°C or above. The former is made by treating arsenic metal or arsenious oxide with nitric acid. Also, the pentoxide can be prepared by the reaction of arsenic trioxide with oxygen under pressure. 

In some cases, e.g. the oxidation of hydrocarbons by potassium permanganate (Meyer and Saam, Ber. xxx. 1935, 1897), the hydrolysis of emulsions of esters in water CGoldschmidt, Zeit. Phys. Ghem. xxxi. 235, 1899), and the dissmution of arsenious oxide (Drucker, Zeit. Phys. Ghem. xxxvi. 693, 1901), the actual chemical reaction between solvent and solute appears to be slower than the process of diffusion, and thus the rate of chemical action is independent of the diffusion coefficient. 

In 1649 Johann Schroeder published a pharmacopoeia in which he gave two methods of obtaining metallic arsenic (1) by decomposing orpiment, arsenious sulfide, with lime and (2) by reducing arsenious oxide with charcoal. 

On his way home from the Netherlands he studied mining and metallurgy in the Harz, and in 1727 he was placed in charged of the chemical laboratory at the Bureau of Mines in Stockholm, which was then in poor financial condition. After the laboratory was sold, Brandt and his students Henrik Teofil Scheffer and Axel Fredrik Cronstedt carried on their epoch-making researches at the Royal Mint, and in 1730 Brandt became assay master of the Mint. Three years later he published a systematic investigation of arsenic and its compounds in which he showed that arsenic is a semi-metal and that white arsenic [arsenious oxide] is its calx (35). 

Arsenic acid obtained by oxidizing arsenious oxide with nitric acid is satisfactory a syrupy acid of 80-85 Per cent purity can be obtained on the market. 

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