Mercury II chloride

Mercury(II) chloride, HgC, corrosive sublimate, m.p. 280 C, b.p. 302"C. Essentially covalent material (Hg plus CL Hg plus aqua regia). Forms complex halide ions, e.g. (HgCU) (HgCL)" in excess HCl and forms complexes. Very poisonous. 

In presence of hydrochloric acid, tin(II) in aqueous solution (1) is precipitated by hydrogen sulphide as brown SnS, and (2) will reduce mercury(II) chloride first to mercury(I) chloride (white precipitate) and then to metallic mercury. 

Tin(IV) in aqueous acid gives a yellow precipitate with hydrogen sulphide, and no reaction with mercury(II) chloride. 

Addition of mercury(II) chloride solution to a solution of an iodide gives a scarlet precipitate of mercury(II) iodide, soluble in excess of iodide ... 

Mercury compounds (for example mercury(II) chloride) are used in medicine because of their antiseptic character. The artificial red mercury(Il) sulphide is the artist s vermilion . Mercury(II) sulphate is a catalyst in the manufacture of ethanal from ethyne ... 

The aqueous solution has a low conductivity, indicating that mercury(II) chloride dissolves essentially as molecules Cl—Hg—Cl and these linear molecules are found in the solid and vapour. A solution of mercury(II) chloride is readily reduced, for example by tin(ll) chloride, to give first white insoluble mercury(I) chloride and then a black metallic deposit of mercury, The complexes formed from mercury(II) chloride are considered below. 

Mercuration. Mercury(II) salts react with alkyl-, alkenyl-, and arylboranes to yield organomercurials, which are usehil synthetic intermediates (263). For example, dialkyhnercury and alkyhnercury acetates can be prepared from primary trialkylboranes by treatment with mercury(II) chloride in the presence of sodium hydroxide or with mercury(II) acetate in tetrahydrofuran (3,264). Mercuration of 3 -alkylboranes is sluggish and requires prolonged heating. Alkenyl groups are transferred from boron to mercury with retention of configuration (243,265). 

Mercury(II) acetate tends to mercurate all the free nuclear positions in pyrrole, furan and thiophene to give derivatives of type (74). The acetoxymercuration of thiophene has been estimated to proceed ca. 10 times faster than that of benzene. Mercuration of rings with deactivating substituents such as ethoxycarbonyl and nitro is still possible with this reagent, as shown by the formation of compounds (75) and (76). Mercury(II) chloride is a milder mercurating agent, as illustrated by the chloromercuration of thiophene to give either the 2- or 2,5-disubstituted product (Scheme 25). 

Dimethylpyrazole (L) reacts with mercury(II) chloride to give complexes of the structure L2(HgCl2)3. In connection with metallotropy (Section 4.04.1.5.1) the behaviour of compounds (295) has been described. These phenylmercury derivatives were synthesized by the action of phenylmercury hydroxide on the appropriate pyrazole (71MI40400). 

Dithiols, like diols, have been protected as 5,5 -methylene, 5,5 -isopropylidene, and 5,5 -benzylidene derivatives, formed by reaction of the dithiol with formaldehyde, acetone, or benzaldehyde, respectively. The methylene and benzylidene derivatives are cleaved by reduction with sodium/ammonia. The isopropylidene and benzylidene derivatives are cleaved by mercury(II) chloride with sodium/ ammonia the isopropylidene derivative is converted to a monothio ether, HSCHR-CHRSCHMe2- ... 

Chemical Designations - Synonyms Albus Aminomercuric chloride Ammoniated mercury Mercuric chloride, ammoniated Mercury ammonium chloride Mercury (II) chloride ammonobasic Chemical Formula HgNHjCl. 

Chemical Designations - Synonyms. Calochlor Corrosive mercury chloride Corrosive sublimate Mercury bichloride Mercury (II) chloride Mercury perchloride Chemical Formula-. HgClj Observable Characteristics(as shipped)-. Solid Color. White colorless Odor. None. Physical and Chemical Properties - Physical State at 15 X and 1 atm. Solid Molecular Weight-. 271.50 Boiling Point at I atm. 576, 302, 575 Freezing Point 531, 277, 550 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 5.4 at 20 °C (solid) Vapor (Gas) Specific Gravity Not pertinent Ratio of Specific Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat of Combustion Heat of Decomposition Not pertinent. 

Mercury(II) nitrate monohydrate Mercury(II) chloride Nitric acid 0.1 mol/1 Titrisol Nitric acid (65%)... 

Merkur, m. mercury, -blende, /. Min.) cinnabar. -chlorid, n. mercury chloride, specif, mercuric chloride, mercury(II) chloride, -chloriir, n. mercurous chloride, mercury(I) chloride, -gelb, n. mercury yellow, turpeth mineral. 

Procedure. Weigh out accurately about 2.5 g of finely powdered mercury(II) chloride, and dissolve it in 100 mL of water in a graduated flask. Shake well. Transfer 25.0 mL of the solution to a conical flask, add 25 mL water, 2mL 1M hydrochloric acid, and excess of 50 per cent phosphorous(III) acid solution. Stir thoroughly and allow to stand for 12 hours or more. Filter the precipitated mercury(I) chloride through a quantitative filter paper and wash the precipitate moderately with cold water. Transfer the precipitate with the filter paper quantitatively to a 250 mL reagent bottle, add 30 mL concentrated hydrochloric acid, 20 mL water, and 5 mL carbon tetrachloride or chloroform. Titrate the mixture with standard 0.025M potassium iodate in the usual manner (Section 11.127). 

After the addition of the mercury(II) chloride solution, the whole is allowed to stand for five minutes, then diluted to about 400 mL and titrated with standard... 

Solution (i) dissolve 5.4g finely powdered mercury(II) chloride in lOOmL of distilled water slight warming may be necessary. 

If nitric acid solutions of mercury(II) nitrate are used, the latter must be converted into mercury(II) chloride by the addition of at least an equivalent amount of chloride ion. 

This anion is determined similarly to phosphite (Section 11.70), i.e. indirectly as mercury(I) chloride, Hg2Cl2. In this case the reaction with mercury(II) chloride solution is ... 

Determination of phosphite as mercury(I) chloride Discussion. The acid solution of phosphite reduces mercury(II) chloride solution to mercury(I) chloride which is weighed. The reaction is ... 

---