Zinc acetate

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Zinc acetate
Zinc acetate crystals
Identifiers
CAS number 557-34-6 YesY5970-45-6
PubChem 11192
ChemSpider 10719 YesY
UNII H2ZEY72PME YesY
ChEMBL CHEMBL1200928 N
RTECS number ZG8750000
ATC code A16AX05
Jmol-3D images Image 1
Properties
Molecular formula ZnC4H6O4 (dihydrate)
Molar mass 219.50 g/mol (dihydrate)
183.48 g/mol (anhydrous)
Appearance White solid (all forms)
Density 1.735 g/cm3 (dihydrate)
Melting point Decomposes at 237 °C (459 °F; 510 K)
(dihydrate loses water at 100 °C)
Boiling point decomposes
Solubility in water 43 g/100 mL (20 °C, dihydrate)
Solubility soluble in alcohol
Structure
Coordination
geometry
octahedral (dihydrate)
Molecular shape tetrahedral
Hazards
R-phrases R22 R36 R50/53
S-phrases S26 S60 S61
Main hazards mildly toxic
Related compounds
Other anions Zinc chloride
Other cations Copper(II) acetate
Related compounds Basic beryllium acetate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Zinc acetate is a salt with the formula Zn(O2CCH3)2, which commonly occurs as the dihydrate Zn(O2CCH3)2(H2O)2. Both the hydrate and the anhydrous forms are colorless solids that are commonly used in chemical synthesis and as dietary supplements. Zinc acetates are prepared by the action of acetic acid on zinc carbonate or zinc metal. When used as a food additive, it has the E number E650.

Basic properties and structures[edit]

In anhydrous zinc acetate the zinc is coordinated to four oxygen atoms to give a tetrahedral environment, these tetrahedral polyhedra are then interconnected by acetate ligands to give a range of polymeric structures.[1][2][3] In contrast, most metal diacetates feature metals in octahedral coordination with bidentate acetate groups.

In zinc acetate dihydrate the zinc is octahedral, wherein both acetate groups are bidentate.[4][5]

Basic zinc acetate[edit]

Heating Zn(CH3CO2)2 in a vacuum results in a loss of acetic anhydride, leaving a residue of basic zinc acetate, with the formula Zn4O(CH3CO2)6. This cluster compound has the tetrahedral structure shown below. This species closely resembles the corresponding beryllium compound, although it is slightly expanded with Zn-O distances ~1.97 vs ~1.63 Å for Be4O(OAc)6.[6]

BasicZnAcetate.png

Applications[edit]

Dietary and medicinal applications[edit]

Zinc acetate has been used in lozenges for treating the common cold. Pooling the results of three high dose zinc acetate trials indicates an average 42% reduction in the duration of colds (see figure).[7]

This forest plot shows the effect of high dose zinc (>75 mg/day) as zinc acetate lozenges on common cold duration in three randomized placebo-controlled trials. Constructed from data in Table 3 of Hemilä 2011: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3136969.The three horizontal lines indicate the three studies, and the diamond shape at the bottom indicates the pooled effect of zinc: decrease in the duration of colds by 42% (95%CI: 35 to 48%).

Zinc acetate is a particularly useful salt in lozenges since acetate does not bind zinc, with the result that essentially all zinc from the lozenges is freely released.[8][9]

Although zinc acetate lozenges appear to be able to shorten the duration of colds, some zinc lozenges may be more effective than others. Among the factors affecting the usefulness of a zinc lozenge are the total dose of zinc provided as well as the presence of substances like citric acid which may bind up much of the zinc that the lozenge is providing.[10]

Zinc acetate can also be used to treat zinc deficiencies. As an oral daily supplement it is used to inhibit the body's absorption of copper as part of the treatment for Wilson's disease. Zinc acetate is also sold as an astringent in the form of an ointment, a topical lotion, or combined with an antibiotic such as erythromycin for the topical treatment of acne. It is commonly sold as a topical anti-itch ointment.

In chewing gum, zinc acetate is a breath freshener[11][12] and plaque inhibitor.[13]

Industrial applications[edit]

Industrial applications include wood preservation, manufacturing other zinc salts, polymers, manufacture of ethylene acetate, as a dye mordant, and analytical reagent. It is used in commercial nuclear power plants as a plating inhibitor on primary water piping.

See Also[edit]

References[edit]

  1. ^ Clegg, W.; Little, I. R.; Straughan, B. P. (15 December 1986). "Monoclinic anhydrous zinc(II) acetate". Acta Crystallographica Section C Crystal Structure Communications 42 (12): 1701–1703. doi:10.1107/S010827018609087X. 
  2. ^ He, Hongshan (15 November 2006). "A new monoclinic polymorph of anhydrous zinc acetate". Acta Crystallographica Section E Structure Reports Online 62 (12): m3291–m3292. doi:10.1107/S1600536806046678. 
  3. ^ Capilla, A. V.; Aranda, R. A. (1979). "Anhydrous Zinc(II) Acetate (CH3-COO)2Zn". Crystal Structure Communications 8: 795–797. 
  4. ^ van Niekerk, J. N.; Schoening, F. R. L.; Talbot, J. H. (10 September 1953). "The crystal structure of zinc acetate dihydrate, Zn(CH3COO)2.2H2O". Acta Crystallographica 6 (8): 720–723. doi:10.1107/S0365110X53002015. 
  5. ^ Ishioka, T.; Murata, A.; Kitagawa, Y.; Nakamura, K. T. (15 August 1997). "Zinc(II) Acetate Dihydrate". Acta Crystallographica Section C Crystal Structure Communications 53 (8): 1029–1031. doi:10.1107/S0108270197004484. 
  6. ^ Koyama, H.; Saito, Y. (1954). "The Crystal Structure of Zinc Oxyacetate, Zn4O(CH3COO)6". Bull. Chem. Soc. Japan 27 (2): 112–114. doi:10.1246/bcsj.27.112. 
  7. ^ Hemilä, Harri (23 June 2011). "Zinc Lozenges May Shorten the Duration of Colds: A Systematic Review". The Open Respiratory Medicine Journal 5 (1): 51–58. doi:10.2174/1874306401105010051. PMC 3136969. PMID 21769305. 
  8. ^ Eby, George A. "Zinc Lozenges: Cold Cure or Candy? Solution Chemistry Determinations". Bioscience Reports 24 (1): 23–39. doi:10.1023/B:BIRE.0000037754.71063.41. 
  9. ^ Eby, George A. (Mar 2010). "Zinc lozenges as cure for the common cold – A review and hypothesis". Medical Hypotheses 74 (3): 482–492. doi:10.1016/j.mehy.2009.10.017. PMID 19906491. 
  10. ^ Eby G (2009) Zinc Lozenges as a Common Cold Treatment
  11. ^ US 7087255 
  12. ^ US 6592849 
  13. ^ Giertsen E, Svatun B, Saxton A (February 1987). "Plaque inhibition by hexetidine and zinc". Scand J Dent Res 95 (1): 49–54. doi:10.1111/j.1600-0722.1987.tb01392.x. PMID 3470899.