Mercury(II) chloride

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Mercury(II) chloride
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Names
IUPAC names
Mercury(II) chloride
Mercury dichloride
Other names
Mercury bichloride
Corrosive sublimate
Abavit
Mercuric chloride
Sulema (Russia)
TL-898
Agrosan
Hydrargyri dichloridum (homeopathy)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.028.454 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-299-8
KEGG
PubChem CID
RTECS number
  • OV9100000
UNII
UN number 1624
  • InChI=1S/2ClH.Hg/h2*1H;/q;;+2/p-2 X mark.svgN
  • Cl[Hg]Cl
Properties
HgCl2
Molar mass 271.52 g/mol
Appearancecolorless or white solid
Odor odorless
Density 5.43 g/cm3
Melting point 276 °C (529 °F; 549 K)
Boiling point 304 °C (579 °F; 577 K)
3.6 g/100 mL (0 °C)
7.4 g/100 mL (20 °C)
48 g/100 mL (100 °C)
Solubility 4 g/100 mL (ether)
soluble in alcohol, acetone, ethyl acetate
slightly soluble in benzene, CS2, pyridine
Acidity (pKa)3.2 (0.2M solution)
82.0·10−6 cm3/mol
1.859
Structure
orthogonal
linear
linear
zero
Thermochemistry
Std molar
entropy
(S298)
144 J·mol−1·K−1 [1]
−230 kJ·mol−1 [1]
-178.7 kJ/mol
Pharmacology
D08AK03 ( WHO )
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Highly toxic, corrosive.
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H300+H310+H330, H301, H314, H341, H361f, H372, H410
P201, P202, P260, P264, P270, P273, P280, P281, P301+P310, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P314, P321, P330, P363, P391, P405, P501
NFPA 704 (fire diamond)
4
0
1
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
32 mg/kg (rats, orally)
Safety data sheet (SDS) ICSC 0979
Related compounds
Other anions
Mercury(II) fluoride
Mercury(II) bromide
Mercury(II) iodide
Other cations
Zinc chloride
Cadmium chloride
Mercury(I) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, [2] is the inorganic chemical compound of mercury and chlorine with the formula HgCl2. It is white crystalline solid and is a laboratory reagent and a molecular compound that is very toxic to humans. Once used as a treatment for syphilis, it is no longer used for medicinal purposes because of mercury toxicity and the availability of superior treatments.

Contents

Synthesis

Mercuric chloride is obtained by the action of chlorine on mercury or on mercury(I) chloride. It can also be produced by the addition of hydrochloric acid to a hot, concentrated solution of mercury(I) compounds such as the nitrate: [2]

Hg2(NO3)2 + 4 HCl → 2 HgCl2 + 2 H2O + 2 NO2

Heating a mixture of solid mercury(II) sulfate and sodium chloride also affords volatile HgCl2, which can be separated by sublimation. [2] Process for synthesis of Mercuric chloride first appeared in Abu Bakr al-Razi's De aluminibus et salibus. [3]

Properties

Mercuric chloride exists not as a salt composed of discrete ions, but rather is composed of linear triatomic molecules, hence its tendency to sublime. In the crystal, each mercury atom is bonded to two chloride ligands with HgCl distance of 2.38 Å; six more chlorides are more distant at 3.38 Å. [4]

Its solubility increases from 6% at 20 °C (68 °F) to 36% in 100 °C (212 °F). In the presence of chloride ions, it dissolves to give the tetrahedral coordination complex [HgCl4]2−.

Applications

The main application of mercuric chloride is as a catalyst for the conversion of acetylene to vinyl chloride, the precursor to polyvinyl chloride:

C2H2 + HCl → CH2=CHCl

For this application, the mercuric chloride is supported on carbon in concentrations of about 5 weight percent. This technology has been eclipsed by the thermal cracking of 1,2-dichloroethane. Other significant applications of mercuric chloride include its use as a depolarizer in batteries and as a reagent in organic synthesis and analytical chemistry (see below). [5] It is being used in plant tissue culture for surface sterilisation of explants such as leaf or stem nodes.

As a chemical reagent

Mercuric chloride is occasionally used to form an amalgam with metals, such as aluminium. [6] Upon treatment with an aqueous solution of mercuric chloride, aluminium strips quickly become covered by a thin layer of the amalgam. Normally, aluminium is protected by a thin layer of oxide, thus making it inert. Aluminium can experience a variety of reactions after amalgamation. For example, upon removal of the oxide layer, the exposed aluminium will immediately react with water generating Al(OH)3 and hydrogen gas. Halocarbons react with amalgamated aluminium in the Barbier reaction. These alkylaluminium compounds are nucleophilic and can be used in a similar fashion to the Grignard reagent. Amalgamated aluminium is also used as a reducing agent in organic synthesis. Zinc is also commonly amalgamated using mercuric chloride.

Mercuric chloride is used to remove dithiane groups attached to a carbonyl in an umpolung reaction. This reaction exploits the high affinity of Hg2+ for anionic sulfur ligands.

Mercuric chloride may be used as a stabilising agent for chemicals and analytical samples. Care must be taken to ensure that detected mercuric chloride does not eclipse the signals of other components in the sample, such as is possible in gas chromatography. [7]

Historical use in photography

Mercury(II) chloride was used as a photographic intensifier to produce positive pictures in the collodion process of the 1800s. When applied to a negative, the mercury(II) chloride whitens and thickens the image, thereby increasing the opacity of the shadows and creating the illusion of a positive image. [8]

Historical use in preservation

For the preservation of anthropological and biological specimens during the late 19th and early 20th centuries, objects were dipped in or were painted with a "mercuric solution". This was done to prevent the specimens' destruction by moths, mites and mold. Objects in drawers were protected by scattering crystalline mercuric chloride over them. [9] It finds minor use in tanning, and wood was preserved by kyanizing (soaking in mercuric chloride). [10] Mercuric chloride was one of the three chemicals used for railroad tie wood treatment between 1830 and 1856 in Europe and the United States. Limited railroad ties were treated in the United States until there were concerns over lumber shortages in the 1890s. [11] The process was generally abandoned because mercuric chloride was water-soluble and not effective for the long term, as well as being highly poisonous. Furthermore, alternative treatment processes, such as copper sulfate, zinc chloride, and ultimately creosote; were found to be less toxic. Limited kyanizing was used for some railroad ties in the 1890s and early 1900s. [12]

Historic use in medicine

Mercuric chloride was a common over-the-counter disinfectant in the early twentieth century, recommended for everything from fighting measles germs [13] to protecting fur coats [14] and exterminating red ants. [15] A New York physician, Carlin Philips, wrote in 1913 that "it is one of our most popular and effective household antiseptics", but so corrosive and poisonous that it should only be available by prescription. [16] A group of physicians in Chicago made the same demand later the same month. The product frequently caused accidental poisonings and was used as a suicide method. [17]

It was used to disinfect wounds by Arab physicians in the Middle Ages. [18] It continued to be used by Arab physicians into the twentieth century, until modern medicine deemed it unsafe for use.

Syphilis was frequently treated with mercuric chloride before the advent of antibiotics. It was inhaled, ingested, injected, and applied topically. Both mercuric-chloride treatment for syphilis and poisoning during the course of treatment were so common that the latter's symptoms were often confused with those of syphilis. This use of "salts of white mercury" is referred to in the English-language folk song "The Unfortunate Rake". [19]

Yaws was treated with mercuric chloride (labeled as Corrosive Sublimate) before the advent of antibiotics. It was applied topically to alleviate ulcerative symptoms. Evidence of this is found in Jack London's book The Cruise of the Snark in the chapter entitled "The Amateur M.D."

Historic use in crime and accidental poisonings

Toxicity

Mercury dichloride is highly toxic compound, [28] both acutely and as a cumulative poison. Its toxicity is due not just to its mercury content but also to its corrosive properties, which can cause serious internal damage, including ulcers to the stomach, mouth, and throat, and corrosive damage to the intestines. Mercuric chloride also tends to accumulate in the kidneys, causing severe corrosive damage which can lead to acute kidney failure. However, mercuric chloride, like all inorganic mercury salts, does not cross the blood–brain barrier as readily as organic mercury, although it is known to be a cumulative poison.

Common side effects of acute mercuric chloride poisoning include burning sensations in the mouth and throat, stomach pain, abdominal discomfort, lethargy, vomiting of blood, corrosive bronchitis, severe irritation to the gastrointestinal tract, and kidney failure. Chronic exposure can lead to symptoms more common with mercury poisoning, such as insomnia, delayed reflexes, excessive salivation, bleeding gums, fatigue, tremors, and dental problems.

Acute exposure to large amounts of mercuric chloride can cause death in as little as 24 hours, usually due to acute kidney failure or damage to the gastrointestinal tract. In other cases, victims of acute exposure have taken up to two weeks to die. [29]

Related Research Articles

Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and abbreviations such as "perc" (or "PERC"), and "PCE", is a chlorocarbon with the formula Cl2C=CCl2. It is a colorless liquid widely used for dry cleaning of fabrics, hence it is sometimes called "dry-cleaning fluid". It also has its uses as an effective automotive brake cleaner. It has a sweet odor, similar to the smell of chloroform, detectable by most people at a concentration of 1 part per million (1 ppm). Worldwide production was about 1 million metric tons (980,000 long tons; 1,100,000 short tons) in 1985.

Vinyl chloride is an organochloride with the formula H2C=CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). About 13 million tonnes are produced annually. VCM is among the top twenty largest petrochemicals (petroleum-derived chemicals) in world production. The United States currently remains the largest VCM manufacturing region because of its low-production-cost position in chlorine and ethylene raw materials. China is also a large manufacturer and one of the largest consumers of VCM. Vinyl chloride is a gas with a sweet odor. It is highly toxic, flammable, and carcinogenic. It can be formed in the environment when soil organisms break down chlorinated solvents. Vinyl chloride that is released by industries or formed by the breakdown of other chlorinated chemicals can enter the air and drinking water supplies. Vinyl chloride is a common contaminant found near landfills. In the past VCM was used as a refrigerant.

<span class="mw-page-title-main">Mercury poisoning</span> Poisoning caused by mercury chemicals

Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashes, anxiety, memory problems, trouble speaking, trouble hearing, or trouble seeing. High-level exposure to methylmercury is known as Minamata disease. Methylmercury exposure in children may result in acrodynia in which the skin becomes pink and peels. Long-term complications may include kidney problems and decreased intelligence. The effects of long-term low-dose exposure to methylmercury are unclear.

<span class="mw-page-title-main">Diphosgene</span> Chemical compound

Diphosgene is an organic chemical compound with the formula ClCO2CCl3. This colorless liquid is a valuable reagent in the synthesis of organic compounds. Diphosgene is related to phosgene and has comparable toxicity, but is more conveniently handled because it is a liquid, whereas phosgene is a gas.

<span class="mw-page-title-main">Dimethylmercury</span> Organomercury chemical compound

Dimethylmercury ((CH3)2Hg), also known as Mercury dimethanide, is an extremely toxic organomercury compound. A highly volatile, reactive, flammable, and colorless liquid, dimethylmercury is one of the strongest known neurotoxins, with a quantity of less than 0.1 mL capable of inducing severe mercury poisoning resulting in death, and is easily absorbed through the skin. Dimethylmercury is capable of permeating many materials, including plastic and rubber compounds. It has a slightly sweet odor.

<span class="mw-page-title-main">Parathion</span> Chemical compound

Parathion, also called parathion-ethyl or diethyl parathion and locally known as "Folidol", is an organophosphate insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, including humans, so its use has been banned or restricted in most countries. The basic structure is shared by parathion methyl.

<span class="mw-page-title-main">Mercurial diuretic</span>

Mercurial diuretics are a form of renal diuretic containing mercury.

<span class="mw-page-title-main">Mercury(I) chloride</span> Chemical compound

Mercury(I) chloride is the chemical compound with the formula Hg2Cl2. Also known as the mineral calomel (a rare mineral) or mercurous chloride, this dense white or yellowish-white, odorless solid is the principal example of a mercury(I) compound. It is a component of reference electrodes in electrochemistry.

<span class="mw-page-title-main">Copper(I) chloride</span> Chemical compound

Copper(I) chloride, commonly called cuprous chloride, is the lower chloride of copper, with the formula CuCl. The substance is a white solid sparingly soluble in water, but very soluble in concentrated hydrochloric acid. Impure samples appear green due to the presence of copper(II) chloride (CuCl2).

<span class="mw-page-title-main">Calomel</span> Mineral form of the mercury(I) chloride

Calomel is a mercury chloride mineral with formula Hg2Cl2 (see mercury(I) chloride). The name derives from Greek kalos (beautiful) and melas (black) because it turns black on reaction with ammonia. This was known to alchemists.

Ethylmercury (sometimes ethyl mercury) is a cation composed of an organic CH3CH2- species (an ethyl group) bound to a mercury(II) centre, making it a type of organometallic cation, and giving it a chemical formula C2H5Hg+. The main source of ethylmercury is thimerosal.

Phosgene oxime, or CX, is an organic compound with the formula Cl2CNOH. It is a potent chemical weapon, specifically a nettle agent. The compound itself is a colorless solid, but impure samples are often yellowish liquids. It has a strong, disagreeable and irritating odor. It is used as a reagent in organic chemistry.

<span class="mw-page-title-main">Sulfuryl chloride</span> Chemical compound

Sulfuryl chloride is an inorganic compound with the formula SO2Cl2. At room temperature, it is a colorless liquid with a pungent odor. Sulfuryl chloride is not found in nature, as can be inferred from its rapid hydrolysis.

<span class="mw-page-title-main">Organomercury chemistry</span> Group of chemical compounds containing mercury

Organomercury chemistry refers to the study of organometallic compounds that contain mercury. Typically the Hg–C bond is stable toward air and moisture but sensitive to light. Important organomercury compounds are the methylmercury(II) cation, CH3Hg+; ethylmercury(II) cation, C2H5Hg+; dimethylmercury, (CH3)2Hg, diethylmercury and merbromin ("Mercurochrome"). Thiomersal is used as a preservative for vaccines and intravenous drugs.

<span class="mw-page-title-main">Mercuric amidochloride</span> Chemical compound

Mercuric amidochloride is an inorganic compound with the formula Hg(NH2)Cl.

Metal toxicity or metal poisoning is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds. Certain metals have no biological role, i.e. are not essential minerals, or are toxic when in a certain form. In the case of lead, any measurable amount may have negative health effects. It is often thought that only heavy metals can be toxic, but lighter metals such as beryllium and lithium may also be in certain circumstances. Not all heavy metals are particularly toxic, and some are essential, such as iron. The definition may also include trace elements when abnormally high doses may be toxic. An option for treatment of metal poisoning may be chelation therapy, a technique involving the administration of chelation agents to remove metals from the body.

<span class="mw-page-title-main">Mercury (element)</span> Chemical element, symbol Hg and atomic number 80

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum from the Greek words hydor (water) and argyros (silver). A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature.

<span class="mw-page-title-main">Amalgam (chemistry)</span> Alloy of mercury with another metal

An amalgam is an alloy of mercury with another metal. It may be a liquid, a soft paste or a solid, depending upon the proportion of mercury. These alloys are formed through metallic bonding, with the electrostatic attractive force of the conduction electrons working to bind all the positively charged metal ions together into a crystal lattice structure. Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore. Dentistry has used alloys of mercury with metals such as silver, copper, indium, tin and zinc.

<span class="mw-page-title-main">Perchloromethyl mercaptan</span> Chemical compound

Perchloromethyl mercaptan is the organosulfur compound with the formula CCl3SCl. It is mainly used as an intermediate for the synthesis of dyes and fungicides (captan, folpet). It is a colorless oil, although commercial samples are yellowish. It is insoluble in water but soluble in organic solvents. It has a foul, unbearable, acrid odor. Perchloromethyl mercaptan is the original name. The systematic name is trichloromethanesulfenyl chloride, because the compound is a sulfenyl chloride, not a mercaptan.

References

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  2. 1 2 3 Chisholm, Hugh, ed. (1911). "Corrosive Sublimate"  . Encyclopædia Britannica . Vol. 7 (11th ed.). Cambridge University Press. p. 197.
  3. McAuliffe, Charles Andrew (2016-03-21). The Chemistry of Mercury. Springer. ISBN   978-1-349-02489-6.
  4. Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN   0-19-855370-6.
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  6. Deng, James; Wang, Yu-Pu; Danheiser, Rick L. (2015). "Synthesis of 4,4-Dimethoxybut-1-yne". Organic Syntheses. 92: 13–25. doi: 10.15227/orgsyn.092.0013 .
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