Silver sulphate

The process of isolation finally adopted by the former authors consists in precipitating as reineckates the water-soluble bases contained in a methyl alcoholic extract of the curare. The mixed reineckates are further purified, by solution in acetone and precipitation with water as often as may be necessary. The product so cleaned represents the bulk of the biological activity of the crude drug the mother liquors may contain curine (p. 374), which indicates a menisperm as one of the components of such curares. The mixed reineckates are then fractionated chromato-graphically over alumina and the components isolated as chlorides by the use of silver sulphate and barium chloride in succession. This process has been modified in detail by Schmid and Karrer, who have also found that with their curare, the more soluble reineckate fraction includes less potent quaternary alkaloids. 

Another procedure utilises standard oxalic acid solution. When a sulphuric acid solution of a persulphate is treated with excess of standard oxalic acid solution in the presence of a little silver sulphate as catalyst, the following reaction occurs ... 

Weigh out accurately 0.3-0.4 g potassium persulphate into a 500 mL conical flask, add 50 mL of 0.05 M-oxalic acid, followed by 0.2 g of silver sulphate dissolved in 20 mL of 10 per cent sulphuric acid. Heat the mixture in a water bath until no more carbon dioxide is evolved (15-20 minutes), dilute the solution to about 100 mL with water at about 40 °C, and titrate the excess of oxalic acid with standard 0.02 M potassium permanganate. 

Notes. (1) This solution is prepared by dissolving 5g of silver sulphate in 500 mL of concentrated sulphuric acid. 

Silver bromide Silver chloride Silver perchlorate Silver cyanide Silver fluoride Silver iodide Silver permar>gate Silver nitrate Silver carbonate Silver oxide Silver sulphate Silver sulphide Silver phosphate... 

Many platinum analogs, and analogs based on other metal centres, have been prepared and evaluated. Carboplatin (7.89, cA-diammine(l,l cyclobutanedicarboxalato)platinum) has markedly reduced gastrointestinal and renal toxicity in comparison with cisplatin. It is prepared by the treatment of cA-Pt(NH3)2l2 with silver sulphate, followed by the barium salt of 1,1-cyclobutanedicarboxylic acid. 

Many other ammines of silver salts have been prepared thus, silver sulphate forms with ammonia diammino-silver sulphate, [Ag2(NH3)2]S04, and tetrammino-silver sulphate, [Ag(NI-I3)2]2S04. a... 

Nitro-pentammino-chromic Sulphate, [Cr(NH3)6N02]S04, is formed by rubbing the chloride with water and the calculated quantity of silver sulphate, filtering off silver chloride and precipitating the salt from the filtrate with alcohol. 

The sulphato-derivative, [Pd(NH3)2S04], crystallises in orange-yellow octahedra, is soluble in cold water, and is precipitated from aqueous solution by hydrochloric acid. It is obtained by treating the hydroxo-compound with sulphuric acid, or by the double decomposition of the chloride with silver sulphate.2... 

The sulphate, [Pt(NH3)4]S04, may be prepared by treating the chloride with silver sulphate, or by the addition of sulphuric acid to a solution of the chloride. In the latter case an acid salt is first formed which crystallises in nacreous leaflets. This decomposes on boiling with water in presence of ammonia, yielding the neutral sulphate. It is sparingly soluble in water but soluble in sulphuric acid. Chlorine and bromine oxidise it, as in the case of the chloride. 

Chloro-triammino-platinous Sulphate, [Pt(NH3)3Cl]S04, is obtained by treating the chloroplatinite with silver sulphate. It crystallises in colourless needles which are sparingly soluble in cold water but soluble in boiling water. 

The sulphato-derivative, [Pt(NH3)2S04].H20, is formed by treating the chloro- or iodo-derivative with silver sulphate. It is yellowish white in colour and soluble in hot water. 

Silver sulphate [10294-26-5J M 311.8. Crystd by dissolving in hot cone H2SO4 containing a trace of HNO3, cooling and diluting with water. The ppte was filtered off, washed and dried at 120°. 

By reducing silver sulphate in a current of hydrogen Stas also determined the ratio ... 

Especially interesting from the evidence which it supplies as to the possibility of a bimolecular structure for sulphur trioxide is the formation of this substance when sulphuryl chloride and silver sulphate are heated together.8 This reaction would be expected to follow the course... 

The importance of the determination of sulphuric acid and sulphates lies very largely in the fact that sulphur in various forms of combination, and also free sulphur, is frequently determined quantitatively by primary conversion into sulphuric acid or sulphate, followed by actual estimation in the latter form. For example, a convenient volumetric process applicable to the Carius method for determining sulphur in organic compounds is to neutralise the solution of sulphuric acid after removal of the excess of nitric acid by evaporation, and then add silver nitrate, by which the sulphate is converted into silver sulphate. This is separated from the excess of silver nitrate by means of its insolubility in alcohol, and is then estimated by dissolving in dilute nitric acid and titrating the silver with standard thiocyanate solution.3... 

Oxidation processes involving the subsequent titration of an excess of ferrous sulphate,2 oxalic acid (in the presence of silver sulphate as catalyst), titanous chloride,4 or of the quantity of iodine liberated from potassium iodide,5 are also available but are less satisfactory. In the last-named method a large excess of potassium iodide is necessary to obtain complete reaction in a short time. The reaction may be accelerated by the addition of potassium chloride6 or ammonium chloride with 20 per cent, by weight of the latter salt present a large excess of the iodide is not necessary and the liberated iodine may be titrated after fifteen minutes.7... 

Trimethylplatinic sulphate, [(CH3)3Pt]2S04.2H20, occurs when equivalent quantities of the iodide and silver sulphate in moist acetone or benzene are boiled together for several hours. The compound consists of colourless rectangular plates. 

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