Mercury iodide, solubility-product

The solubility product constant of mercury(I) iodide is 1.2 X 10 at 25°C. Estimate the concentration of Hg2 and 1 in equilibrium with solid Hg2l2. 

In 1856, Nessler recommended an alkaline solution of mercury(ll) iodide and potassium iodide as a reagent for the determination of ammonia [24]. Nessler s reagent reacts with ammonia in an alkaline medium, to give a brown-orange, sparingly soluble product, according to the following equation ... 

Since the mercury ditolyl has practically the same solubility in xylene as the tolylmercuric iodide and chloride, the latter will be present in the recrystallized product if the reaction has not gone to completion. A trace of unchanged product may readily be detected by the metallic sodium test for inorganic halides. 

Reaction of l,l -di(chloromercuri) ferrocene with sodium iodide or sodium thiosulfate might be expected to lead to higher homologs of XXIX in which ferrocene units are bridged by atoms of mercury. Reactions of this type have produced apparently polymeric materials with structures such as XXX, although the very limited solubility of the products has thus far precluded reliable molecular weight measurements (80). 

Soluble starch, available from chemical supply houses, is readily dispersed in water. The iodine-starch complex has limited water solubility, and it is therefore important not to add the starch indicator until near the end point when the iodine concentration is low. Because starch is subject to attack by microorganisms, the solution usually is prepared as needed. Among the products of hydrolysis is dextrose, which can cause large errors because of its reducing action. Various substances have been recommended as preservatives, including mercury(II) iodide and thymol. With formamide a clear solution containing 5% starch is obtained that is stable indefinitely. 

A suspension of 2 75 grams of 8-acetylamino-4-hydroxyphenylarsinic acid in 30 c.c. of ice-cold water is quickly dissolved by the addition of 11 c.c. of 2iV sodium hydroxide, then treated with an ice-cooled solution of 3-2 grams of mercuric acetate in 2 c.c. of acetic acid and 20 c.c. of water. After keeping in the dark for six to seven days, the yellowish-brown precipitate is washed with water and dried. Any unchanged arsinic acid is removed from the product by shaking witli methyl alcohol the yield is quantitative. The compound is not decomposed below 300° C. it is soluble in sodium carbonate, caustic alkali, and ammonia solutions. Saponification of the acid cannot be accomplished without decomposition. The position of the mercury has been proved by shaking the compound with iodine in potassium iodide, when 5-iodo-S-acetylamino-4i-hydroa yphenylarsinic acid results. 

Trimethylarsine, (CH3)3 As (78), has been synthesized from CH3MgI and Asl3. The product 78 is stable when kept in benzene solution. 78 forms with mercury(II) chloride a complex Me3 As-HgCl2 (79) soluble in water. 78 can be liberated from 79 by reduction of the Hg(II) with zinc powder or by addition of an excess of potassium iodide. 

Mercury di-n-octyl. —Octyl iodide is treated with dilute sodium amalgam in the presence of ethyl acetate, and after completion of the reaction the mass is extracted with ether. Evaporation of the solvent gives an oily liquid of density 1 342 at 17° C., which decomposes at about 200° C. into di-octyl and metallic mercury. When the starting materials are pure it is stated that no by-products occur. Mercury di-n-octyl is insoluble in water, but readily soluble in alcohol, ether, or benzene. Treatment with alcoholic iodine or mercuric chloride yields the corresponding di-n-oetyl mercuric halides. 

The monomercurated compound is obtained from the more soluble fractions by extraction with ether, dissolving the residue in potassium hydroxide solution and adding hydrochloric acid. Monochloro-mercuri-6-nitro-3-hydroxybenzaidehyde is thus precipitated. It decomposes at 198° C. (corr.). The dimerciirated product is converted by 5 per cent, bromine in alcohol into 2 4-dibromo-6-nitro-3-hydroxy-benzaldehyde, and with iodine in potassium iodide solution into 2 4-di-iodo-6-nitro-3-hydroxybenzaldehyde. The monomercuri compound in a similar manner yields monoiodo-6-nitro-3-hydroxybenzaldehyde. 

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