Arsenic acid pentoxide

The arsenic acid solution is prepared by dissolving 123 g. of arsenic pentoxide in 104 ml. of water 100 ml. of the cold solution are used in the experiment. 

Arsenic Peroxides. Arsenic peroxides have not been isolated however, elemental arsenic, and a great variety of arsenic compounds, have been found to be effective catalysts ia the epoxidation of olefins by aqueous hydrogen peroxide. Transient peroxoarsenic compounds are beheved to be iavolved ia these systems. Compounds that act as effective epoxidation catalysts iaclude arsenic trioxide, arsenic pentoxide, arsenious acid, arsenic acid, arsenic trichloride, arsenic oxychloride, triphenyl arsiae, phenylarsonic acid, and the arsenates of sodium, ammonium, and bismuth (56). To avoid having to dispose of the toxic residues of these reactions, the arsenic can be immobi1i2ed on a polystyrene resia (57). 

These precursors are prepared by reaction of fuming nitric acid in excess acetic anhydride at low temperatures with 2-furancarboxaldehyde [98-01-1] (furfural) or its diacetate (16) followed by treatment of an intermediate 2-acetoxy-2,5-dihydrofuran [63848-92-0] with pyridine (17). This process has been improved by the use of concentrated nitric acid (18,19), as well as catalytic amounts of phosphoms pentoxide, trichloride, and oxychloride (20), and sulfuric acid (21). Orthophosphoric acid, -toluenesulfonic acid, arsenic acid, boric acid, and stibonic acid, among others are useful additives for the nitration of furfural with acetyl nitrate. Hydrolysis of 5-nitro-2-furancarboxyaldehyde diacetate [92-55-7] with aqueous mineral acids provides the aldehyde which is suitable for use without additional purification. 

Arsenic Acids and the Arsenates. Commercial arsenic acid, corresponds to the composition, one mole of arsenic pentoxide to four moles of water, and probably is the arsenic acid hemihydrate [7774-41-6] H AsO O.5H2O. It is obtained by treatment of arsenic trioxide with concentrated nitric acid. Solutions of this substance or of arsenic pentoxide in water behave as triprotic acids with successive dissociation constants = 5.6 x 10 , ... 

Arsenic acid (arsenic pentoxide hydrate, arsenic V oxide hydrate, orthoarsenic acid) [12044 50-7] M 229.8 + XH2O, pKj 2.26, pK 6.76, pKj 11.29 (H3ASO4). Cryst from cone solns of... 

Amino-3-fluorophenol Arsenic acid and its salts Arsenic pentoxide Arsenic trioxide Asbestos (all types)... 

Allyl alcohol Aluminum phosphide 4-Aminopyridine Arsenic acid Arsenic pentoxide Arsenic trioxide Calcium cyanide Carbon disulfide p-Chloroaniline... 

Arsenic acid is prepared by treating arsenic trioxide with concentrated nitric acid or by combination of arsenic pentoxide with water. The latter reaction is very slow. It is also formed when meta- or pyroarsenic acid is treated with cold water. 

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. 

The aqueous solution of arsenic pentoxide is arsenic acid which probably corresponds to the hemihydrate formula H3ASO4 O.5H2O. See Orthoarsenic acid. It behaves as a triprotic acid forming various arsenate derivatives of metals. 

ARSENIC ACID Arsenic Pentoxide, Ortlioarsenic Acid Poisonous, Class B, I(L) II(S) 4 0 2 ... 

Antimony Arsenite.—When powdered antimony is digested with a concentrated aqueous solution of arsenic acid, and the solution then diluted with water, a precipitate forms, which was described by Berzelius 6 as antimony arsenite. He obtained a similar product by heating a mixture of arsenic and antimony pentoxide it remained as a transparent vitreous mass. The exact composition of these products does not appear to have been investigated. 

The reaction of arsenic acid solutions with hydrogen sulphide has been the subject of much investigation and it is found that arsenic pentasulphide or arsenic trisulphide may be precipitated as the main product, according to conditions.12 Thus, in an aqueous solution of the pentoxide at the ordinary temperature and in the presence of 8 to 14 per cent, of hydrochloric acid, the precipitate is the pentasulphide as the concentration of hydrochloric acid is increased, the trisulphide and sulphur are also precipitated in increasing proportion, and at 32 to 33... 

A light form of magnesium arsenate may be obtained by heating a slurry of magnesium hydroxide with the theoretical quantity of arsenic acid and 15 per cent, of the equivalent amount of sodium hydroxide in an autoclave at 180° C. until the filtrate contains less than 0-2 per cent, of arsenic pentoxide.3... 

The free acid of the first series has been obtained in yellow plates by boiling vanadium pentoxide with a solution of arsenic acid. Its... 

Zinc Arsenates.—Zinc Orthoarsenate, Zng(As04)2, has been obtained in the anhydrous form by heating zinc carbonate with aqueous arsenic acid to 200° C.6 or by fusing a mixture of zinc chloride and arsenic pentoxide.7 The latter process yields prismatic crystals of density 4-913 at 15° C. The trihydrate, Zn3(As04)2.3H20, is precipitated... 

For the Mexican boll weevil a specially prepared calcium arsenate containing up to 20 per cent, of arsenic pentoxide is effective. This is prepared by heating together white arsenic and precipitated chalk in the presence of excess air at 650° C. The cotton plant is not injured by this preparation.10 In Peru about 30,000 acres of cotton fields are dusted annually from aeroplanes with calcium arsenate. Acid arsenates of calcium appear to be more toxic to boll weevils and to locusts than the basic arsenates. This is probably because the latter must be partially hydrolysed to compounds giving more soluble arsenic before toxic results are produced.11 The extensive application of such sprays to cotton plants is frequently followed by heavy infestations of the cotton aphis. This appears to be due in the first place to the positive photo-tropism of the winged females to white substances such as the arsenate, chalk or flour. Increase of the aphis population is then aided by the destruction by the spray of the hymenopterous parasites of the aphis.12... 

Arsenic Pentoxide—Hydrates of Arsenic Pentoxide—Manufacture of Arsenic Acid—Properties of Arsenic Acid Solutions—The Arsenates—Perarsenates. 

SYNS ANHYDRIDE ARSENTQUE (FRENCH) ARSENIC ACID ARSENIC ACID ANHYDRIDE ARSENIC ANHYDRIDE ARSENIC OXIDE ARSENIC(V) OXIDE DLARSENIC PENTOXIDE RCRA WASTE NUMBER poll ZOTOX... 

Arsenic pentoxide, AsgO, is not obtained by burning arsenic, but can be made by boiling arsenic trioxide with concentrated nitric acid. With water it forms arsenic acid. HgAsO, which is closely similar to... 

Ores of arsenic orpiment, realgar, arsenolite, arsenopyrite. Compounds of arsenic arsine, arsenic trioxide, arsenious acid, cupric hydrogen arsenite, arsenic pentoxide, arsenic acid, sodium arsenate. The Marsh test for arsenic. U.ses of arsenic and its compounds lead shot, insecticides, weed killers, chemotherapy. 

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