Chloride-free preparations

An attempt to demonstrate the direct outer-sphere reduction of HOC1 was recently published, in which the reductant was selected to be [Ru(NH3)5isn]2+ because of its well-known behavior as an outer-sphere reductant and its relatively low standard potential (10). In this reagent the ligand isn is isonicotinamide. Further efforts to promote reaction via HOC1 entailed the use of chloride-free preparations of HOC1. 

Neutralize the chloride-free prepared sample from above or a 100-mL fresh sample if already chloride free to about pH 7 with dilute NaOH. Transfer to a casserole and evaporate to dryness. Mix the residue with 2.0 mL phenoldi-sulfonic acid reagent, using a glass rod to help dissolve the solids heat on a hot-water bath if necessary to aid dissolution. Dilute with 20 mL distilled water and then add 6 to 7 mL ammonia until maximum color is developed. If a floc-culent hydroxide forms, dissolve it by adding the EDTA reagent dropwise with stirring. (Alternatively, the sample may be filtered.) Transfer the clear solution to a 50-mL volumetric flask and dilute to volmne with distilled water. 

Dextrin Polyethylene glycol 400 Use 5 mL of 2% aqueous solution of chloride-free dextrin per 25 mL of 0. IM halide solution. Prepare a 50% (v/v) aqueous solution of the surfactant. Use 5 drops per 100 mL end-point volume. 

Reduced pressure distillation of a mixture of chlorine octahydrate and HgO provides a distillate with about 25% HOCl (55,129). Chloride-free aqueous solutions of up to 76% HOCl can be obtained by dissolving Hquid CI2O, prepared by reaction of CI2 and HgO, in the appropriate amount of water (3). Alternatively, the gaseous CI2O can be absorbed in cold water to give lower concentrations of HOCl In addition, a CI2O solution in CCl can be extracted with H2O to give CU and Cl2-free HOCl solutions of up to 5 M (51). 

Either the Mohr titration or the adsorption indicator method may be used for the determination of chlorides in neutral solution by titration with standard 0.1M silver nitrate. If the solution is acid, neutralisation may be effected with chloride-free calcium carbonate, sodium tetraborate, or sodium hydrogencarbonate. Mineral acid may also be removed by neutralising most ofthe acid with ammonia solution and then adding an excess of ammonium acetate. Titration of the neutral solution, prepared with calcium carbonate, by the adsorption indicator method is rendered easier by the addition of 5 mL of 2 per cent dextrin solution this offsets the coagulating effect of the calcium ion. If the solution is basic, it may be neutralised with chloride-free nitric acid, using phenolphthalein as indicator. 

Reagents. Supporting electrolyte. For chloride and bromide, use 0.5 M perchloric acid. For iodide, use 0.1M perchloric acid plus 0.4M potassium nitrate. It is recommended that a stock solution of about five times the above concentrations be prepared (2.5M perchloric acid for chloride and bromide 0.5M perchloric acid + 2.0A f potassium nitrate for iodide), and dilution to be effected in the cell according to the volume of test solution used. The reagents must be chloride-free. 

Alkanesulfonyl chlorides are prepared in good yields by the photoreaction of sulfur dioxide and chlorine with saturated hydrocarbons.89 157 158 This sulfochlorination, known as the Reed reaction,159 presumably proceeds by a free-radical mechanism 158 160... 

Benzyl chloride is prepared by free-radical chlorination of toluene. 

Fig. 6.12. Acid-free preparation of carboxylic chloride from carboxylic acids and a chloro-enamine.

Methods of Preparation using Chloride-Free Gold Precursors... 

If sulfonation is done with a large excess of chlorosulfonic acid without a solvent, the sulfochloride is formed, as a rule, instead of the free sulfonic acid. For example, large quantities of the mixture of o- and p-toluenesulfoi l chlorides are prepared in this way ... 

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