Potassium mercuri-iodide, preparation

Iodine is used in various forms in medicine—e.g. tincture of iodine, liquor iodi, iodized cotton, iodized wine, iodized water, oils and syrups iodides of potassium, mercury, iron, arsenic, lead, etc. and as methyl iodide or di-iodide iodoform, CHI3 ethyl iodide, C2H5I iodole, C4I4.NH aristole etc.—largely for external application as an antiseptic. Some iodides are used in photography, and in analytical operations and a considerable amount of iodine is used in the preparation of aniline dyes. 

Preparation of Mercury(II) Iodide. Prepare a 0.02 N solution of mercury(II) nitrate. Boil 2-3 ml of the solution, add an equal volume of a 0.02 N potassium iodide solution, and let the mixture stand to your next lesson. Filter off the precipitate (what is its composition ) through a paper filter, wash it with water, and dry it in a drying cabinet at 70 °C. What happens to the salt when it is kept in the air ... 

Titanium diiodide may be prepared by direct combination of the elements, the reaction mixture being heated to 440°C to remove the tri- and tetraiodides (145). It can also be made by either reaction of soHd potassium iodide with titanium tetrachloride or reduction of Til with silver or mercury. 

The following is an alternative method of preparation. Dissolve lOOg mercury(II) iodide and 70g potassium iodide in 100mL ammonia-free water. Add slowly, and with stirring, to a cooled solution of 160 g sodium hydroxide pellets (or 224 g potassium hydroxide)in 700 mL ammonia-free water, and dilute to 1 L with ammonia-free distilled water. Allow the precipitate to settle, preferably for a few days, before using the pale yellow supernatant liquid. 

P. Lemoult obtained phosphorus trisiodomercuriate, P(HgI)8, by the action of phosphine, diluted with hydrogen or carbon dioxide, on a dil, soln. of potassium iodomercuriate. The product is washed and dried in vacuo. It is slowly decomposed by warm water and rapidly by alkali-lye. Nitric acid and aqua regia decompose it violently. F. Venturoli prepared "yellow phosphorus iodobisiodo-mercuriate, I.P (Hgl)2, by the action of phosphorus on an alcoholic soln. of potassium iodide. The product is decomposed by heat into phosphorus, and mercurous and mercuric iodides. 

The mercury(n) iodide reagent is prepared by dissolving 6.6 g of mercury(n) chloride (POISONOUS) in a solution of 16.3 g of potassium iodide in 16.3 ml of water and adding 12.5 ml of 10 per cent sodium hydroxide solution. 

Mercury diphenyl has been prepared in a number of ways. The most important methods are by the action of sodium on a mixture of bromobcnzene and mercuric chloride 1 from sodium amalgam and phenyl mercuric iodide 2 by the interaction of phenyl mercuric bromide and potassium sulfide2 or phenyl mercuric acetate and sodium stannite 3 from phenyl magnesium bromide and mercuric chloride 4 by the action of phenyl hydrazine on mercury compounds 5 from mercuric chloride and phenyl arsenious oxide 6 and from diphenyl mercuric ammonium acetate and sulfur compounds.7... 

An alternative method for the preparation of the reagent is as follows. Dissolve 23 g mercury(II) iodide and 16 g potassium iodide in ammonia-free water and make up the volume to 100 ml add 100 ml 6m sodium hydroxide. Allow to stand for 24 hours, and decant the solution from any precipitate that may have formed. The solution should be kept in the dark. 

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