Lead(II) acetate

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Lead(II) acetate is a white crystalline chemical compound with a slightly sweet taste. Its chemical formula is usually expressed as Template:Chem2 or Template:Chem2, where Ac represents the acetyl group. Like many other lead compounds, it causes lead poisoning. Lead acetate is soluble in water and glycerin. With water it forms the trihydrate, Template:Chem2, 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 formerly served as the principal active ingredient in progressive types of hair colouring dyes.[1] Lead(II) acetate is also used as a mordant in textile printing and dyeing, and as a drier in paints and varnishes. It was historically used as a sweetener and preservative in wines and in other foods and for cosmetics.

Production

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

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Lead(II) acetate can also be made by dissolving lead(II) oxide in acetic acid:[2]

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

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Structure

The crystal structure of anhydrous lead(II) acetate has been described as a 2D coordination polymer. In comparison, lead(II) acetate trihydrate's structure is a 1D coordination polymer.[3] In the trihydrate, the Pb2+ ion's coordination sphere consists of nine oxygen atoms belonging to three water molecules, two bidentate acetate groups and two bridging acetate groups. The coordination geometry at Pb is a monocapped square antiprism.[4][5] The trihydrate thermally decomposes to a hemihydrate, Pb(OAc)2·<templatestyles src="Fraction/styles.css" />1⁄2H2O, and to basic acetates such as Pb4O(OAc)6 and Pb2O(OAc)2.[3]

Comparison of anhydrous and trihydrate crystal structures
Anhydrous[3]
Pb(OAc)2 		Trihydrate[4][5]
Pb(OAc)2·3H2O
Lead
coordination
sphere 		File:Lead(II)-acetate-xtal-Pb-coordination-3D-bs-17.png File:Lead(II)-acetate-trihydrate-xtal-Pb-coordination-3D-noH-bs-17.png
Strongly bonded
aggregation 		File:Lead(II)-acetate-xtal-one-layer-3D-bs-17.png
2D sheet 		File:Lead(II)-acetate-trihydrate-xtal-chain-3D-noH-bs-17.png
1D chain
Weakly bonded
aggregation 		File:Lead(II)-acetate-xtal-layers-3D-bs-17.png
sheets stacked with
hydrophobic surfaces in contact 		File:Lead(II)-acetate-trihydrate-xtal-packing-HB-3D-noH-bs-17.png
chains linked by hydrogen bonds

Uses

Lead acetate is used as a precursor to other lead compounds such as the various carbonate.

Niche and laboratory 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 a byproduct of the process used in the cleaning and maintenance of stainless steel firearm suppressors (silencers) and compensators when using a 1:1 ratio of hydrogen peroxide and white vinegar (acetic acid). The solution is agitated by the bubbling action of the hydrogen peroxide, with the main reaction being the oxidation of lead by hydrogen peroxide and subsequent dissolution of lead oxide 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.

Historical uses

Sweetener

Like other lead(II) salts, lead(II) acetate has a sweet taste, which led to its historical use as a sugar substitute in both wines and foods.[6] The ancient Romans, who had few sweeteners besides honey, would boil must (unfiltered 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 because of its recognized toxicity. Legislation prohibiting its use as a wine sweetener circa 1750 proved ineffective until decades later, when chemical methods of detecting its presence had been developed.[8]

The earliest confirmed poisoning by lead acetate was that of Pope Clement II, who 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 sugar of lead.[9] It is not clear whether he was assassinated.

In 1787 painter and biographer Albert Christoph Dies swallowed, by accident, approximately Template:Convert of lead acetate. His recovery from this poison was slow and incomplete. He lived with illnesses until his death in 1822.[10][11]

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).[12][13]

In 1887, 38 hunting horses belonging to Captain William Hollwey Steeds were poisoned in their stables at Clonsilla House, Dublin, Ireland. At least ten of the horses died. Captain Steeds, an "extensive commission agent," had previously supplied the horses for the Bray and Greystones Coach. It transpired that they had been fed a bran mash that had been sweetened with a toxic lead acetate.[14]

Cosmetics

Lead(II) acetate and white lead have been used in cosmetics throughout history.[15]

It was once used for men's hair colouring products[16] like Grecian Formula. The manufacturer did not remove lead acetate from its product until 2018. Lead acetate has been replaced by bismuth citrate as the progressive colorant. Its use in cosmetics has been banned in Canada by Health Canada since 2005 (effective at the end of 2006) based on tests showing possible carcinogenicity and reproductive toxicity,[17] and it is also banned in the European Union.[17]

Medical uses

Lead(II) acetate solution was a commonly used folk remedy for sore nipples.[18] In modern medicine, for a time, it was used as an astringent, in the form of Goulard's extract, and it has also been used to treat poison ivy.[19]

In the 1850s, Mary Seacole applied lead(II) acetate, among other remedies, against an epidemic of cholera in Panama.[20][21]

Other historic uses

It was also used in making of slow match during the Middle Ages. It was made by mixing vinegar with litharge, a natural form of lead(II) oxide.

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.[22]

Lead(II) acetate ("salt of Saturn") was used to synthesise acetone which was then known as "spirit of Saturn" for being made with the salt of Saturn and thought to be a lead compound in the 17th century.[23]

See also

References

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External links

Template:Sister project

Template:Lead compounds Template:Acetates

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  6. ↑ "The Disturbingly Long History of Lead Toxicity in Winemaking." Anna Archibald, 30 July 2020. Retrieved: 22 December, 2020.
  7. ↑ Script error: No such module "citation/CS1".
  8. ↑ Script error: No such module "citation/CS1".
  9. ↑ Specht, W. and Fischer, K. (1959). Script error: No such module "Lang". [Evidence of poisoning in the remains of a 900-year-old corpse] (in German). Script error: No such module "Lang". 124: 61–84.
  10. ↑ File:Wikisource-logo.svg One or more of the preceding sentences incorporates text from a publication now in the public domain: Script error: No such module "template wrapper".
  11. ↑ Script error: No such module "citation/CS1". English translation in: Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ Weekly Irish Times, Saturday 15 October 1887; Enniskillen Chronicle and Erne Packet, 24 October 1887, p. 3
  15. ↑ Gunn, Fenja. (1973) The Artificial Face: A History of Cosmetics. — as cited in Leisure Activities of an 18th Century Lady websites.umich.edu
  16. ↑ 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).
  17. ↑ a b Script error: No such module "citation/CS1".
  18. ↑ The American Frugal Housewife, by Lydia M. Child gutenberg.org
  19. ↑ Laboratory manual in biology. Sharpe. 1911, American Book Company. p. 351
  20. ↑ Mary Seacole (1990), Wonderful Adventures of Mrs. Seacole in Many Lands, Chapter IV, Oxford University Press reprint, Template:ISBN; (2005 Penguin 20th Century Classics reprint, ed. Sarah Salih) Template:ISBN
  21. ↑ Jane Robinson (2004), Mary Seacole: The Charismatic Black Nurse who became a heroine of the Crimea, p.53. Constable Template:ISBN
  22. ↑ 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.
  23. ↑ Mel Gorman, History of acetone (1600–1850), 1962
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