Silver chloride purification

Silver chloride is a common source and intermediate product in many extractive metallurgical processes, for example it occurs in the anode slimes from copper refineries, the residues of leaching processes for base metals, as a product of the chlorination of impure gold—silver bullion, and in photographic waste. A novel process for the leaching and purification of silver chloride, which was devised by Parker et a/.,26 is based on the observation that silver chloride is very soluble in some dipolar aprotic solvents containing chloride ion but is much less soluble when water is present. The very different behaviour of the equilibrium... 

Silicon, higher chlorides of, 42 Silicon tetrabromide, 38, 40 Silicon tetrachloride, 44 Silicopropane, octachloro, 44 Silicotungstic acid, 129 analysis, 131 ether complex, 131 Silver, metallic, 4 Silver chloride, reduction of, 3 Silver cyanamide, 98 Silver residues, purification of, 2 Sodium amalgam, 10 Sodium amide, 74 Sodium azide, purification of, 79 Sodium azidodithiocarbonate, 82 Sodium butoxide, 88 Sodium hypochlorite (solution), 90 Sodium iodate, 168 Sodium metaperiodate, 170 Sodium paraperiodate, chlorine method, 169 persulfate method, 170 Strontium amalgam, 11 Sulfur hexafluoride, 121 Sulfuryl chloride, 114... 

An account of the elaborate research of Richards and Stahler 2 on potassium chloride appeared in 1907. The salt employed was prepared by the action of hydrogen chloride on potassium nitrate purified by repeated recrystallization with special precautions. After several crystallizations, the chloride was fused in a current of nitrogen. The silver was obtained by reducing the nitrate with ammonium formate. After electrolytic purification, it was fused in a lime-boat in a current of hydrogen, and finally in vacuo. In the analyses the silver required to precipitate the chlorine from a known weight of potassium chloride was determined, and also the weight of silver chloride produced ... 

Lead chloride precipitation Is hot quantitative for lead under normal conditions but can be useful for radiochemical purification of a lead fraction. It can also be used to remove the bulk of a large quantity of lead prior to more complete separations. Although sparingly soluble In cold water, lead, chloride (PbClg) Is readily soluble In hot water or In dilute, hot nitric add. This has been used as a separation from silver by precipitation of silver chloride from hot nitric add solutions (H3). Tlra (T1) reports that the condition for maximum yield of PbClg with hydrochloric add at 20 C occurs at pH 0.5... 

B. Bis(2,4,6-trimethylpyridine)iodine(l) hexafluorophosphate. A 1-L, threenecked, round-bottomed flask equipped with a mechanical stirrer, condenser topped with a drying tube containing calcium chloride, and a stopper is charged with 500 mL of dry methylene chloride (Note 6), 82.5 g of bis(trimethylpyridine)silver(l) hexafluorophosphate (0.166 mol), and 41.9 g of iodine (0.165 mol). The mixture is stirred until all the iodine is consumed (1 hr - 2 hr) (Note 7). The resulting yellow solid (silver iodide) is suction filtered, and washed with 100 mL of dry methylene chloride. The filtrate is concentrated on a rotary evaporator at a maximum bath temperature of 30°C to give 68-76 g (80-88%) of yellowish solid bis(2,4,6-trimethylpyridine)iodine(l) hexafluorophosphate (mp 132-133°C) (Notes 8, 9, and 10). This product is suitable for reactions without further purification. 

The resulting yellowish solid (silver bromide) is suction filtered and washed with 100 mL of dried methylene chloride. The filtrate is concentrated on a rotary evaporator at a maximum bath temperature of 30°C to give 65-74 g (83-95%) of bis(2,4,6-trimethylpyridine)bromine(l) hexafluorophosphate (mp 127-128 C) as a white solid (Notes 9,12, and 13). This product is suitable for reactions without further purification. 

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