Mercury(II) Fulminate - Wikipedia

Mercury(II) fulminate

O − − N + ≡ C − Hg − C ≡ N + − O − {\displaystyle {\ce {{}^{-}O-{\overset {+}{N}}#C-Hg-C#{\overset {+}{N}}-O^{-}}}}
Names
IUPAC name Mercury(II) fulminate
Systematic IUPAC name Dioxycyanomercury
Other names Fulminated Mercury Bis(fulminato-kappaC)mercury Knallquecksilber (German) bis[(oxidoazanylidyne)methyl]mercury
Identifiers
CAS Number	628-86-4 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:39152 Y
ChemSpider	9197626 Y
ECHA InfoCard	100.010.053
PubChem CID	11022444
UNII	O8H2ZFF76L Y
CompTox Dashboard (EPA)	DTXSID40893599
InChI InChI=1S/2CNO.Hg/c2*1-2-3; YKey: MHWLNQBTOIYJJP-UHFFFAOYSA-N Y InChI=1/2CNO.Hg/c2*1-2-3;/rC2HgN2O2/c6-4-1-3-2-5-7Key: MHWLNQBTOIYJJP-HZIBCBEIAJ
SMILES [O-][N+]#C[Hg]C#[N+][O-]
Properties
Chemical formula	Hg(CNO)2
Molar mass	284.626 g·mol−1
Appearance	Grey, pale brown, or white crystalline solid
Density	4.42 g/cm3
Melting point	160 °C (320 °F; 433 K)
Boiling point	356.6 °C (673.9 °F; 629.8 K)
Solubility in water	slightly soluble
Solubility in ethanol	soluble
Solubility in ammonia	soluble
Explosive data[1]
Shock sensitivity	High 5 cm (2 kg weight, 20 mg, Bureau of Mines apparatus) 4 in (1 lb weight, 30 mg, Picatinny Arsenal apparatus)
Friction sensitivity	High (explodes with fiber & steel shoe tests)
RE factor	37% to 50% (Trauzl lead block)
Hazards[2]
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H200, H301, H311, H331, H373, H410
Precautionary statements	P201, P202, P260, P261, P262, P264, P270, P271, P273, P280, P281, P301+P316, P302+P352, P304+P340, P316, P319, P321, P330, P361+P364, P372, P373, P380, P391, P401, P403+P233, P405, P501
NFPA 704 (fire diamond)	4 1 4
Autoignitiontemperature	170 °C (338 °F; 443 K)
Threshold limit value (TLV)	0.02 mg/m3, 0.01 mg/m3 (TWA), 0.03 mg/m3 (skin, 15 minute) (STEL)
NIOSH (US health exposure limits):[3]
PEL (Permissible)	0.01 mg/m3 (TWA, 8h) 0.04 mg/m3 (ceiling)
REL (Recommended)	0.01 mg/m3 (TWA, skin) 0.03 mg/m3 (STEL, skin)
IDLH (Immediate danger)	2 mg/m3 (as Hg)
Related compounds
Other anions	Mercury(II) cyanide Mercury(II) thiocyanate
Other cations	Potassium fulminate Silver fulminate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Chemical compound

Mercury(II) fulminate is a primary explosive with the chemical formula Hg(CNO)2. When recrystallized from water it exists as the hemihydrate 2 Hg(CNO)2·H2O. The anyhydrous form is obtained by recrystallization from ethanol.[1]: F217  It is highly sensitive to friction, heat and shock and is mainly used as a trigger for other explosives in percussion caps and detonators. Mercury(II) cyanate, though its chemical formula is identical, has a different atomic arrangement, making the cyanate and fulminate anionic isomers.

First used as a priming composition in small copper caps beginning in the 1820s, mercury fulminate quickly replaced flints as a means to ignite black powder charges in muzzle-loading firearms. Later, during the late 19th century and most of the 20th century, mercury fulminate became widely used in primers for self-contained rifle and pistol ammunition; it was the only practical detonator for firing projectiles until the early 20th century.[4]

Mercury fulminate has the distinct advantage over potassium chlorate of being non-corrosive, but it is known to attack aluminum and magnesium strongly, and brass, bronze, copper, and zinc slowly when dry; when wet it immediately reacts with aluminum and magnesium and strongly attacks brass, bronze, copper and zinc.[1] Today, mercury fulminate has been replaced in primers by more efficient chemical substances. These are non-corrosive, less toxic, and more stable over time; they include lead azide, lead styphnate, and tetrazene derivatives. In addition, none of these compounds requires mercury for manufacture, supplies of which can be unreliable in wartime.[5]

Preparation

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Mercury(II) fulminate is prepared by dissolving mercury in nitric acid and adding ethanol to the solution. Edward Charles Howard is credited with first preparing it in 1800.[6][4] However, Johann Kunckel had discovered the compound more than a century before in the 17th century.[7] The crystal structure of this compound was determined only in 2007.[8]

Silver fulminate can be prepared in a similar way, but this salt is even more unstable than mercury fulminate; it can explode even under water and is impossible to accumulate in large amounts because it detonates under its own weight.[9]

Another preparation method is through reaction of the sodium salt of nitromethane with an aqueous solution of mercury(II) chloride (HgCl2) at 0 °C (32 °F) to form a white precipitate of mercuric nitromethanate. This is digested with warm, dilute hydrochloric acid (HCl) to produce mercury(II) fulminate.[1]: F219 

Intermediates

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The oxidation and nitration of ethanol with nitric acid proceeds through a multitude of intermediate compounds before reaching mercury fulminate; acetaldehyde (CH3CHO), nitrosoacetaldehyde (CH2(NO)−CHO), isonitrosoacetaldehyde (CH(=NOH)−CHO), isonitrosoacetic acid (CH(=NOH)−COOH), nitroisonitrosoacetic acid (C(NO2)(=NOH)−COOH), formonitrolic acid (O2H−CH=NOH), and fulminic acid (C=NOH) are first formed. The last reacts with mercury to produce the fulminate.[1]: F219 

Decomposition

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The thermal decomposition of mercury(II) fulminate can begin at temperatures as low as 100 °C (212 °F), though it proceeds at a much higher rate with increasing temperature.[10]

It may be decomposed with relative safety by reaction with ten times its weight of 20% sodium thiosulfate solution. This may evolve some toxic cyanogen gas.[1]

A possible reaction for the decomposition of mercury(II) fulminate yields carbon dioxide gas, nitrogen gas, and a combination of relatively stable mercury salts.[citation needed]

4 Hg(CNO)2 → 2 CO2 + N2 + HgO + 3 Hg(OCN)CN Hg(CNO)2 → 2 CO + N2 + Hg Hg(CNO)2 → Hg(O−C≡N)2 or Hg(N=C=O)2 2 Hg(CNO)2 → 2 CO2 + N2 + Hg + Hg(CN)2

See also

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• Fulminic acid
• Potassium fulminate

References

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1. ^ a b c d e f Fedoroff, Basil T.; Sheffield, Oliver E. (1 January 1974). "F". Encyclopedia of Explosives and Related Items (PDF). Vol. 6. Dover, NJ: Picatinny Arsenal. pp. F220-221. ADA011845, PATR2700. Retrieved 5 November 2025.
2. ^ Mercury(II) fulminate from PubChem
3. ^ "NIOSH Pocket Guide to Chemical Hazards".
4. ^ a b Wisniak, Jaime (2012). "Edward Charles Howard. Explosives, meteorites, and sugar". Educación Química. 23 (2). Universidad Nacional Autonoma de Mexico: 230–239. doi:10.1016/s0187-893x(17)30114-3. ISSN 0187-893X.
5. ^ Weingart, George W. (1947). Pyrotechnics (2nd ed.). p. 10. Retrieved 5 November 2025. Calomel [Hg2Cl2] is made in this country and sold in normal times at about 65 cents a pound, but due to the scarcity of mercury and the great demand for it in the manufacture of detonating caps the price has recently advanced to several dollars per pound.
6. ^ Edward Howard (1800). "On a New Fulminating Mercury". Philosophical Transactions of the Royal Society of London. 90 (1): 204–238. doi:10.1098/rstl.1800.0012. S2CID 138658702.
7. ^ "300 years after discovery, structure of mercury fulminate finally determined". Phys.org. August 24, 2007. Retrieved 19 February 2025.
8. ^ W. Beck; J. Evers; M. Göbel; G. Oehlinger; T. M. Klapötke (2007). "The Crystal and Molecular Structure of Mercury Fulminate (Knallquecksilber)". Zeitschrift für anorganische und allgemeine Chemie. 633 (9): 1417–1422. doi:10.1002/zaac.200700176.
9. ^ "The Sciences - Fulminating Substances". Scientific American. 11 June 1853.
10. ^ Garner, W. E.; Hailes, H. R. (1933). "Thermal decomposition and detonation of mercury fulminate". Proceedings of the Royal Society of London. 139 (1–3): 1–40. Bibcode:1933CP....334..128S. doi:10.1098/rspa.1933.0040.

External links

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• Media related to Mercury(II) fulminate at Wikimedia Commons

v t e Mercury compounds
Mercury(I)	HgH Hg2H2 Hg2Br2 Hg2Cl2 Hg2F2 Hg2I2 Hg2(NO3)2 Hg2O Hg2SO4 Hg2S (hypothetical)
Mercury(II)	HgH2 HgNH2Cl HgSe HgS HgTe Hg(O2CCH3)2 HgBr2 HgCl2 Hg(CN)2 HgF2 Hg(OH)2 HgI2 Hg(NO3)2 HgO Hg(ClO4)2 HgSO4 Hg(SCN)2 Hg(CNO)2 Hg3N2 Hg(Si(CH3)3)2 K2HgI4 Organomercury compounds Hg(CH3)2 Hg(C2H5)2 Hg(C6H5)2 HgC6H5CH3CO2 HgC6H5OB(OH)2 HgC6H5NO3 HgC6H5CCl3 HgClC6H4CO2H HgOHCH2CHOCH3CH2(NHCO) C36H70HgO4 HgOHCH2CHOCH3CH2NHCOC6H4OCH2CO2H Na2HgOHC6HOBrC6H2OBrOCHC6H4CO2 HgOC6H2CH3NO2 NaHgC2H5SC6H4CO2
Mercury(IV)	HgF4 (hypothetical)
Amalgams	Na(Hg) Al(Hg) K(Hg) Au(Hg) Tl(Hg) Sn(Hg)
Mercury cations	Hg2+ Hg2+2 Hg2+3 Hg2+4 Hg4+3 HgCH+3 HgC2H+5 HgC6H+5