Lead(II) acetate

Lead(II) acetate
Names
IUPAC name
Lead(II) ethanoate
Systematic IUPAC name
Lead(II) ethanoate
Other names
Plumbous acetate, Salt of Saturn, Sugar of Lead, Lead diacetate
Identifiers
301-04-2 YesY
6080-56-4 (trihydrate) N
51404-69-4 (Basic) N
3D model (Jmol) Interactive image
ChEMBL ChEMBL1909062 N
ECHA InfoCard 100.115.474
EC Number 206-104-4
MeSH lead+acetate
PubChem 9317
RTECS number OF8050000
Properties
Pb(C2H3O2)2
Molar mass 325.29 g/mol (anhydrous)
379.33g/mol (trihydrate)
Appearance White powder or colourless, efflorescent crystals
Odor Slightly acetic
Density 3.25 g/cm3 (20 °C, anhydrous)
2.55 g/cm3 (trihydrate)
1.69 g/cm3 (decahydrate)[1]
Melting point 280 °C (536 °F; 553 K) (anhydrous)
75 °C (167 °F; 348 K)
(trihydrate) decomposes[2] at ≥ 200 °C
22 °C (72 °F; 295 K)
(decahydrate)[1]
Boiling point Decomposes
Anhydrous:
19.8 g/100 mL (0 °C)
44.31 g/100 mL (20 °C)
69.5 g/100 mL (30 °C)[3]
218.3 g/100 mL (50 °C)[1]
Solubility Anhydrous and trihydrate are soluble in alcohol, glycerol[3]
Solubility in methanol Anhydrous:[3]
102.75 g/100 g (66.1 °C)
Trihydrate:[4]
74.75 g/100 g (15 °C)
214.95 g/100 g (66.1 °C)
Solubility in glycerol Anhydrous:[3]
20 g/100 g (15 °C)
Trihydrate:[4]
143 g/100 g (20 °C)
1.567 (trihydrate)[1]
Structure
Monoclinic (anhydrous, trihydrate)
Rhombic (decahydrate)
Thermochemistry
−960.9 kJ/mol (anhydrous)[3]
−1848.6 kJ/mol (trihydrate)[4]
Hazards
Main hazards Neurotoxic, probable human carcinogen
GHS pictograms [2]
GHS signal word Danger
H360, H373, H410[2]
P201, P273, P308+313, P501[2]
T N
R-phrases R33, R48/22, R50/53, R61, R62
S-phrases S45, S53, S60, S61
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
1
3
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
400 mg/kg (mice, oral)[1]
300 mg/kg (dog, oral)[5]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references
"Lead sugar" redirects here.

Lead(II) acetate (Pb(CH3COO)2), also known as lead acetate, lead diacetate, plumbous acetate, sugar of lead, lead sugar, salt of Saturn, and Goulard's powder, is a white crystalline chemical compound with a sweetish taste. It is made by treating lead(II) oxide with acetic acid. Like other lead compounds, it is toxic. Lead acetate is soluble in water and glycerin. With water it forms the trihydrate, Pb(CH3COO)2·3H2O, a colourless or white efflorescent monoclinic crystalline substance.

The substance is used as a reagent to make other lead compounds and as a fixative for some dyes. In low concentrations, it is the principal active ingredient in progressive types of hair colouring dyes.[6] Lead(II) acetate is also used as a mordant in textile printing and dyeing, as a drier in paints and varnishes, and in preparing other lead compounds. It was historically used as a sweetener and for cosmetics.

Production

Lead acetate can be made by boiling elemental lead in acetic acid and hydrogen peroxide. This method of using acetic acid and hydrogen peroxide will also work with lead carbonate or lead oxide.

Pb(s) + H2O2 + 2 H+(aq) → Pb2+(aq) + 2 H2O(l)
Pb2+ + 2 CH3COO−(aq) → Pb(CH3COO)2

Lead acetate can also be made via a single displacement reaction between copper acetate and lead metal:

Cu(CH3COO)2 + Pb → Cu + Pb(CH3COO)2

Uses

Sweetener

Like other lead(II) salts, lead(II) acetate has a sweet taste, which has led to its use as a sugar substitute throughout history. The ancient Romans, who had few sweeteners besides honey, would boil must (grape juice) in lead pots to produce a reduced sugar syrup called defrutum, concentrated again into sapa. This syrup was used to sweeten wine and to sweeten and preserve fruit. It is possible that lead(II) acetate or other lead compounds leaching into the syrup might have caused lead poisoning in those who consumed it.[7] Lead acetate is no longer used in the production of sweeteners in most of the world because of its recognized toxicity. Modern chemistry can easily detect it, which has all but stopped the illegal use that continued decades after legal use as a sweetener was banned.[8]

Resultant deaths

Pope Clement II died in October 1047. A toxicological examination of his remains conducted in the mid-20th century confirmed centuries-old rumors that he had been poisoned with lead sugar.[9] It is not clear if he was assassinated.

In 1787 painter Albert Christoph Dies swallowed, by accident, approximately 0.75 ounces (21 g) of lead acetate. His recovery from this poison was slow and incomplete. He lived with illnesses until his death in 1822.

Although the use of lead(II) acetate as a sweetener was already illegal at that time, composer Ludwig van Beethoven may have died of lead poisoning caused by wines adulterated with lead acetate (see also Beethoven's liver).[10][11]

Mary Seacole applied lead(II) acetate, among other remedies, against an epidemic of cholera in Panama.[12][13]

Cosmetics

Lead(II) acetate, as well as white lead, has been used in cosmetics throughout history.[14]

It is still used in men's hair colouring products[15] like Grecian Formula. The Food and Drug Administration considers this use safe because human testing showed lead did not enter the bloodstream and was not shown to be absorbed.[16]

Lead acetate was banned in cosmetics by Health Canada in 2005 (effective at the end of 2006) based on tests showing possible carcinogenicity and reproductive toxicity.[17] It is also banned in the European Union[17] and has been on the California Proposition 65 warning list as a carcinogen since 1988.[18]

Medical uses

Lead(II) acetate solution was a commonly used folk remedy for sore nipples.[19] In modern medicine, for a time, it was used as an astringent, in the form of Goulard's Extract.

Lead(II) acetate has also been used to treat poison ivy.[20]

Industrial uses

Lead(II) acetate paper is used to detect the poisonous gas hydrogen sulfide. The gas reacts with lead(II) acetate on the moistened test paper to form a grey precipitate of lead(II) sulfide.

An aqueous solution of lead(II) acetate is the byproduct of the 50/50 mixture of hydrogen peroxide and white vinegar used in the cleaning and maintenance of stainless steel firearm suppressors (silencers) and compensators. The solution is agitated by the bubbling action of the hydrogen peroxide, and the main reaction is the dissolution of lead deposits within the suppressor by the acetic acid, which forms lead acetate. Because of its high toxicity, this chemical solution must be appropriately disposed by a chemical processing facility or hazardous materials centre. Alternatively, the solution may be reacted with sulfuric acid to precipitate nearly insoluble lead(II) sulfate. The solid may then be removed by mechanical filtration and is safer to dispose of than aqueous lead acetate.

It was also used in making of slow matches during the Middle Ages. It was made by mixing natural form of lead(II) oxide called litharge and vinegar.

Sugar of lead was a recommended agent added to linseed oil during heating to produce "boiled" linseed oil, the lead and heat acting to cause the oil to cure faster than raw linseed oil.[21]

Precautions

Lead(II) acetate, as with any other lead salts, causes lead poisoning.

See also

References

  1. 1 2 3 4 5 Pradyot, Patnaik (2003). Handbook of Inorganic Chemicals. The McGraw-Hill Companies, Inc. ISBN 0-07-049439-8.
  2. 1 2 3 4 Sigma-Aldrich Co., Lead(II) acetate trihydrate. Retrieved on 2014-06-08.
  3. 1 2 3 4 5 http://chemister.ru/Database/properties-en.php?dbid=1&id=1990
  4. 1 2 3 http://chemister.ru/Database/properties-en.php?dbid=1&id=1762
  5. ↑ "Lead compounds (as Pb)". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
  6. ↑ http://www.fda.gov/Cosmetics/ProductsIngredients/Products/ucm143075.htm
  7. ↑ Lead Poisoning and Rome
  8. ↑ Stoeppler, M. (1992), Hazardous Metals in the Environment, Techniques and Instrumentation in Analytical Chemistry, 12, Elsevier, p. 60, ISBN 9780080875606, From the results achieved so far it is obvious that the purity law for lead in wines in the last two centuries was frequently ignored.
  9. ↑ Specht W and Fischer K (1959). Vergiftungsnachweis an den Resten einer 900 Jahre alten Leiche. Arch. Kriminol., 124: 61-84. [Translation:Intoxication evidence in the remains of a 900-year-old corpse]
  10. ↑ Pharmazeutische Zeitung zu Beethovens wahrscheinlicher Bleivergiftung
  11. ↑ Beethoven litt unter Bleivergiftung
  12. ↑ Mary Seacole: Wonderful Adventures of Mrs. Seacole in Many Lands, Chapter IV, (1990 Oxford University Press reprint) ISBN 0-19-506672-3; (2005 Penguin 20th Century Classics reprint, ed. Sarah Salih) ISBN 0-14-043902-1
  13. ↑ Jane Robinson: Mary Seacole: The Charismatic Black Nurse who became a heroine of the Crimea, p.53. Constable 2004 (p/b. ISBN 1-84119-677-0)
  14. ↑ Gunn, Fenja. (1973). The Artificial Face: A History of Cosmetics. — as cited in Leisure Activities of an 18th Century Lady
  15. ↑ Lead Based Hair Products: Too Hazardous for Household Use - Results, Howard W. Mielke, PhD, Myiesha D. Taylor, Chris R. Gonzales, M. Kelley Smith, Pamela V. Daniels, and Ayanna V.Buckner. Journal of American Pharmaceutical Association (NS37, Jan/Feb 1997:85-89).
  16. ↑ http://www.fda.gov/Cosmetics/ProductsIngredients/Products/ucm143075.htm
  17. 1 2 Can West News Service: Grecian Formula in a grey zone after ban
  18. ↑ http://www.oehha.ca.gov/prop65/prop65_list/files/P65single060614.pdf
  19. ↑ The Project Gutenberg eBook of The American Frugal Housewife, by Lydia M. Child
  20. ↑ Laboratory manual in biology. Sharpe. 1911, American Book Company. p. 351
  21. ↑ Andés, Louis Edgar, and Arthur Morris. Oil colours and printers' inks a practical handbook treating of linseed oil, boiled oil, paints, artists' colours, lampblack and printers' inks, black and coloured. London: Scott, Greenwood ;, 1903. 41. Print.

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