593-74-8 Usage
General Description
Mercury dimethyl is a toxic environmental pollutant. It is found in polluted bottom sediments and in the bodies of fishes and birds. In the bodies of fishes and birds it occurs along with monomethyl mercury. The latter, as CH3Hg+ ion, is formed by microorganism-induced biological methylation of elemental mercury or agricultural fungicide mercury compounds that are discharged into the environment.
Mercury dimethyl is used in inorganic synthesis; and as a reference standard for Hg-NMR.
Reaction
Mercury dimethyl, unlike zinc dimethyl, is fairly stable at ordinary temperatures, and is not attacked by air or water.
Mercury dimethyl undergoes single replacement reactions with several metals such as alkali and alkaline earth metals, zinc, aluminum, tin, lead and bismuth forming their corresponding dialkyls.
Such reaction is a synthetic route to prepare many organometallic compounds. Thus, reaction with metallic zinc yields zinc dimethyl:
(CH3)2Hg + Zn → (CH3)2Zn + Hg
Toxicity
Mercury dimethyl is a highly toxic substance by all routes of exposure. Several cases of human poisoning are well documented. (Patnaik, P. 1999. A Comprehensive Guide to the Hazardous Properties of Chemical Substances, 2nd ed. p. 574, New York: John Wiley & Sons.) The compound can accumulate in the brain and blood of humans. Intake of small quantities can cause death.
Description
The first indication of the extreme toxicity of dimethylmercury
(DMM) was documented in 1863 when two laboratory assistants
died of DMM poisoning while synthesizing DMM in the
laboratory of Frankland and Duppa. There are numerous reports
of people dying from alkyl mercury compounds including
a chemist who was preparing several thousand grams ofDMMin
his laboratory in 1974. The extreme toxicity was revisited in
1997, when Karen Wetterhahn, an internationally renowned
researcher of the carcinogenic effects of heavy metals on DNA
repair proteins, died within a few months after a single exposure
of less than a milliliter of DMM on her latex-covered hand.
DMM is extremely toxic and lethal at a dose of approximately
400 mg of mercury (equivalent to a few drops) or about
5mgkg-1 of body weight or as little as 0.1 ml
Chemical Properties
Different sources of media describe the Chemical Properties of 593-74-8 differently. You can refer to the following data:
1. colourless liquid
2. Dimethyl mercury is a volatile colorless liquid
with faint sweet odor.
Uses
Different sources of media describe the Uses of 593-74-8 differently. You can refer to the following data:
1. As inorganic reagent.
2. Dimethylmercury is used as a reagent ininorganic synthesis, and as a reference standardfor mercury nuclear magnetic resonance(Hg NMR). It is an environmental pollutantfound in bottom sediments and also inthe bodies of birds and marine mammalssuch as whales and fishes. It occurs in fishesand birds along with monomethylmercury. Inhumans, its presence is attributed to the consumptionof pilot whale meat, cod fish, andother sea food.
3. DMM has limited use because of its toxicity but can be used to
calibrate research equipment, as in its application as a standard
reference material for 199Hg NMR measurements.
Health Hazard
All alkylmercury compounds are highly toxicby all routes of exposure. There are manyserious cases of human poisoning frommethylmercury (Lu 2003). Outbreaks ofmass poisoning from consumption of contaminatedfish occurred in Japan during the1950s, causing a severe neurological disease,so-called “Minamata disease,” whichresulted in hundreds of deaths. A similaroutbreak of food poisoning from contaminatedwheat caused several hundred deathsin Iraq in 1972. A tragic death from a singleacute transdermal exposure to dimethylmercury(estimated between 0.1 to 0.5 mL) thatpenetrated into the skin through disposablelatex gloves has occurred (Blayney et al.1997; The New York Times, June 11, 1997).The symptoms reported were episodes ofnausea and vomiting occurring three monthsafter the exposure followed by onset ofataxia, slurred speech (dysarthia), and loss ofvision and hearing 2 months after that. Thedeath occurred in about six months after theaccident.Methylmercury can concentrate in certainfetal organs, such as the brain. Thetarget organs are the brain and the centralnervous system. It can cause death, miscarriage,and deformed fetuses. Unlike inorganicmercury compounds, it can penetrate throughthe membrane barrier of the erythrocyte,accumulating at about 10 times greater concentrationthan that in the plasma (WHO1976). Its rate of excretion on the bloodlevel is very slow. It gradually accumulatesin the blood. Such accumulation was found toreach 60% equilibrium at about 90 days, culminatedafter 270 days (Munro and Willes,1978). Skin absorption exhibits the symptomsof mercury poisoning. The toxic thresholdconcentration of mercury in the wholeblood is usually in the range 40 to 50 μg/L,while the normal range should be below10 μg/L.
Fire Hazard
It is a flammable liquid; flash point 38°C
(101°F). The flammability of this compound,
its ease of oxidation and the energy of decomposition is relatively lower than
the alkyls of lighter metals. It is mildly
endothermic. The heat of formation, △H°f
is ＋75.3 kJ/mol (Bretherick 1995). Unlike
most other metal alkyls formed by elements
of lower atomic numbers, dimethylmercury
does not pose any serious fire or explosion
hazard. Although it does not ignite in air,
the compound is easily inflammable. It dissolves
in lower alcohols without any violent
decomposition. Heating with oxidizing substances
can cause explosion. Violent explosion
is reported with diboron tetrachloride at
－63°C (－81°F) under vacuum (Wartik et al.
1971).
Safety Profile
Suspected carcinogen.
Highly toxic. Mutation data reported. Easily
flammable. When heated to decomposition
it emits toxic fumes of Hg.
Potential Exposure
Dimethyl mercury has been
used as seed disinfectants and for fungicides. It has
also been used in organic synthesis.
Environmental Fate
DMM is a colorless liquid that is volatile at room temperature
(vapor pressure 62.3 mmHg) and is slightly soluble in water
(water solubility 8860 mg l-1). There are no reports on the
partition behavior of DMM but it is known to readily evaporate
and is thus rarely found in sediment or soil. No reports were
found on the environmental persistence of DMM. While DMM
vaporizes, no studies were found on long range transport. The
lipophilicity ofDMMresults in its accumulation inadipose tissue,
plasma proteins, and brain. DMM has not been found in fish.
Shipping
UN2025 Mercury compounds, solid, n.o.s.,
Hazard Class: 6.1; Labels: 6.1-Poisonous materials,
Technical Name Required.
Toxicity evaluation
In contrast to the white crystalline solids of the pure forms of
methylmercury (MMM) and phenylmercury, DMM exists as
a colorless liquid at room temperature with high volatility.
These physical qualities enable high concentrations of the
substance to be absorbed by exposure pathways of the skin and
lungs that circumvent first-pass elimination. Effectively, this
prolongs the systemic circulation of DMM, and extends its
residence time in the body.
The additional alkyl group flanking the mercury imparts
DMM with lipophilicity that exceeds its monoalkylated
counterpart, and allows DMM to be sequestered in lipid-rich
depots. The metabolic delay allows the neurotoxicity of DMM
to remain latent for months.
The gradual conversion into MMM results in the release of
DMM from depots such as lipid-rich tissues and plasma
proteins, and permits its movement through barriers such as
the blood–brain and placenta. A cysteine complex of the
monomethylated metabolite penetrates the endothelial cells of
the blood–brain barrier by mimicking methionine and using
the large neutral amino acid transporter.
Thus, the toxicity of DMM is mediated by its dealkylation.
Cleavage of the carbon–mercury bond generates MMM
metabolites, which can form covalent bonds with cellular
ligands with amphiphilic properties. The mercury center reacts
with sulfur and sulfur-containing thiol groups of enzymes
and thereby inhibits them, resulting in cellular dysfunction.
The metal center of DMM acts as a soft acid, and binds tightly
to polarizable donor atoms in soft bases. An additional
mechanism of adverse effect is the disruption of the prooxidant–
antioxidant balance, causing oxidative damage to
biomolecules resulting cellular damage. Within cells, mercury
may interact with a variety of proteins, particularly microsomal
and mitochondrial enzymes. Recent studies demonstrated that
the combined administration of the antioxidants N-acetyl
cysteine, zinc, and selenium mitigated DMM acute and chronic
toxicity by reducing enzymatic and cellular dysfunction.
Check Digit Verification of cas no
The CAS Registry Mumber 593-74-8 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 5,9 and 3 respectively; the second part has 2 digits, 7 and 4 respectively.
Calculate Digit Verification of CAS Registry Number 593-74:
(5*5)+(4*9)+(3*3)+(2*7)+(1*4)=88
88 % 10 = 8
So 593-74-8 is a valid CAS Registry Number.
InChI:InChI=1/2CH3.Hg/h2*1H3;/rC2H6Hg/c1-3-2/h1-2H3
593-74-8Relevant articles and documents
Johns,Hixon
, p. 2226,2232 (1930)
Systematics of the Formation of Π-CO Ligands in Four-Iron Clusters. Synthesis and Structures of *CH2Cl2, Fe4(AuPet3)(CO)12(COCH3), , and
Horwitz, Colin P.,Holt, Elizabeth M.,Brock, Carolyn P.,Shriver, Duward F.
, p. 8136 - 8146 (1985)
The Lewis acid ligands (1+), (1+), and (1+) interact with the metal framework of the tetrahedral iron cluster (2-).In all cases, two products result, one of which consists of the Fe4 tetrahedron with the Lewis acid capping one face.The other more novel product is a Fe4 butterfly array with the Lewis acid ligand on the hinge and a Π-CO between the wingtips.By proper choice of counterion and conditions, either the butterfly or tetrahedral form can be crystallized.X-ray structures were determined for representative compounds of both products in this series.Tetrahedral iron frameworks were observed for (5a) and (6(tetrahedron)).Both *CH2Cl2 (3a) and Fe4(AuPEt3)(CO)12(COCH3) (7) have butterfly iron cores.Butterfly complexes such as 3a display a characteristic and unique low-frequency Π-CO stretch in the 1380-1430-cm-1 region of the IR spectrum.Additionally, NMR spectra of the individual isomers were obtained by dissolving the pure crystalline material at -80 deg C and obtaining the spectrum at this temperature.The NMR spectra obtained in this manner were consistent with both IR spectra of the solid and the structure determined by X-ray crystallography.
Radical Cations of Dialkylmercury Derivatives, Radiation Synthesis and Electron Spin Resonance Detection
Hasegawa, Akinori,Rideout, Jan,Symons, Martyn C.R.
, p. 637 - 640 (1990)
Exposure of very dilute solutions of Hg(CD3)2 in tetrachloromethane to 60Co γ-rays at 77 K gave a species whose e.s.r. spectrum is characteristic of the parent cation.Interpretation of the g-values and 199Hg tensor component B derived from a computer synthesis of the spectrum suggests that the unpaired electron is strongly confined to the linear ? orbital having a node through the mercury atom.This has a large 6p(Hg) character.No extra features were obtained using Hg(13CH3)(CH3), confirming that the spin density on the CH3 groups is small (19F).The spectra for Hg(CH3)2 in this solvent were analysed in terms of the same solvent features together with coupling to a least five and probably seven protons.The small 1H coupling was almost isotropic at +/-4.5 G.In contrast, Hg(C2H5)2 gave no resolved coupling to 19F, but there was a large, well defined, triplet splitting (42 G) assigned to two specific CH3 protons.This suggests that rotation about the C-C bonds is restricted.We were unable to detect free rotation on annealing, although the lines broadened considerably, prior to radical loss.Attempts to detect .CH3 or .CH2CH3 radicals in these systems were unsuccessful, but clear evidence for .CD3 radicals was obtained for Hg(CD3)2 in CFCl3 on annealing.
Protection of Endogenous Thiols against Methylmercury with Benzimidazole-Based Thione by Unusual Ligand-Exchange Reactions
Banerjee, Mainak,Karri, Ramesh,Chalana, Ashish,Das, Ranajit,Rai, Rakesh Kumar,Rawat, Kuber Singh,Pathak, Biswarup,Roy, Gouriprasanna
supporting information, p. 5696 - 5707 (2017/04/28)
Organomercurials, such as methylmercury (MeHg+), are among the most toxic materials to humans. Apart from inhibiting proteins, MeHg+ exerts its cytotoxicity through strong binding with endogenous thiols cysteine (CysH) and glutathione (GSH) to form MeHgCys and MeHgSG complexes. Herein, it is reported that the N,N-disubstituted benzimidazole-based thione 1 containing a N?CH2CH2OH substituent converts MeHgCys and MeHgSG complexes to less toxic water-soluble HgS nanoparticles (NPs) and releases the corresponding free thiols CysH and GSH from MeHgCys and MeHgSG, respectively, in solution by unusual ligand-exchange reactions in phosphate buffer at 37 °C. However, the corresponding N-substituted benzimidazole-based thione 7 and N,N-disubstituted imidazole-based thione 3, in spite of containing a N?CH2CH2OH substituent, failed to convert MeHgX (X=Cys, and SG) to HgS NPs under identical reaction conditions, which suggests that not only the N?CH2CH2OH moiety but the benzimidazole ring and N,N-disubstitution in 1, which leads to the generation of a partial positive charge at the C2 atom of the benzimidazole ring in 1:1 MeHg-conjugated complex of 1, are crucial to convert MeHgX to HgS NPs under physiologically relevant conditions.
Aryl(dimethyl)gallium compounds and methyl(diphenyl)gallium: Synthesis, structure, and redistribution reactions
Jutzi, Peter,Izundu, Joseph,Neumann, Beate,Mix, Andreas,Stammler, Hans-Georg
, p. 4565 - 4571 (2009/02/07)
Treatment of diphenylmercury with an excess of trimethylgallium at higher temperatures resulted in the formation of dimethyl(phenyl)gallium (1). Similarly, reaction of 1-chloromercurio(4-methylbenzene) and 1-chloromercurio(4-tert-butylbenzene) with an excess of trimethylgallium gave dimethyl(4methylphenyl)gallium (2) and dimethyl(4-tert-butylphenyl)gallium (3), respectively. Treatment of diphenylmercury with an equivalent amount of trimethylgallium resulted in the formation of methyl(diphenyl)gallium (4). The X-ray crystallographic studies of compounds 1, 2, 3, and 4 revealed the presence of trigonal planar coordinate gallium atoms in monomeric molecules, which associate to polymeric strands by additional intermolecular gallium π-aryl contacts, thus leading to an overall trigonal bipyramidal coordination geometry at gallium. Compounds 1-4 are stable in the solid state and in solution. Substituent redistribution reactions take place at higher temperatures and at room temperature in the presence of THF. Compound 1 could also be prepared by the reaction of triphenylgallium with an excess of trimethylgallium at higher temperatures.
