Zinc acetate

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Zinc acetate
IUPAC name

Zinc acetate

Other names

Acetic acid, Zinc salt
Acetic acid, Zinc(II) salt
Dicarbomethoxyzinc
Zinc diacetate

Identifiers
CAS number 557-34-6 YesY, 5970-45-6
PubChem 11192
ChemSpider 10719 YesY
UNII H2ZEY72PME YesY
ChEMBL CHEMBL1200928 N
RTECS number ZG8750000
ATC code A16AX05
Jmol-3D images {{#if:[Zn+2].[O-]C(=O)C.[O-]C(=O)C|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 237 °C
(dihydrate loses water at 100 °C)
Boiling point decomp.
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
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Zinc acetate is the chemical compound with the formula Zn(O2CCH3)2, which commonly occurs as a 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

The acetate group is capable of binding to metal ions in a variety of ways through its two oxygen atoms and several connectivities are observed for the various hydrates of zinc acetate. Anhydrous zinc acetate adopts a polymeric structure consisting of zinc coordinated to four oxygen atoms in a tetrahedral environment, each tetrahedron being connected to neighbors by the acetate groups.[1] The acetate ligands are not bidentate. 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.[2]

Basic zinc acetate

Heating Zn(CH3CO2)2 in a vacuum results in 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.[3]

Applications

Dietary and medicinal applications

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 (Figure).[4]

Zinc acetate is particularly useful salt in lozenges since acetate does not bind zinc, so that essentially all zinc from the lozenges is freely released.[5][6]

Although zinc acetate lozenges shorten the duration of colds, most zinc lozenges on the US market, unfortunately, either have too a low dose of zinc or contain ingredients that tightly bind zinc ions, such as citric acid.[7] Therefore, the great benefit seen in the high dose zinc acetate trials may not be easy to actualize.

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. Furthermore Zinc acetate is commonly sold as a topical anti-itch ointment.

In chewing gum, zinc acetate is a breath freshener[8][9] and plaque inhibitor.[10]

Industrial applications

Industrial applications include wood preserving, 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.

Zinc acetate is a precursor via a sol-gel route to the transparent semiconductor zinc oxide.

References

  1. ↑ Capilla, A. V.; Aranda, R. A. (1979). "Anhydrous Zinc(II) Acetate (CH3-COO)2Zn". Crystal Structure Communications 8: 795–797. 
  2. ↑ J. N. van Niekerk, F. R. L. Schoening and J. H. Talbot (1953). "The crystal structure of zinc acetate dihydrate, Zn(CH3COO)2·2H2O". Acta Cryst. 6 (8): 720–723. doi:10.1107/S0365110X53002015. 
  3. ↑ 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. 
  4. ↑ Hemilä H (2011) Zinc lozenges may shorten the duration of colds: a systematic review. Open Respir Med J 5:51-8 Refs with links: http://www.mv.helsinki.fi/home/hemila/Zn/TORMJ.htm
  5. ↑ Eby GA (2004) Zinc lozenges: cold cure or candy? Solution chemistry determinations. Biosci Rep 24:23-39
  6. ↑ Eby GA (2010) Zinc lozenges as cure for the common cold. Med Hypotheses 74:482-92
  7. ↑ Eby G (2009) Zinc Lozenges as a Common Cold Treatment
  8. ↑ US 7087255 
  9. ↑ US 6592849 
  10. ↑ Giertsen E, Svatun B, Saxton A (February 1987). "Plaque inhibition by hexetidine and zinc". Scand J Dent Res 95 (1): 49–54. PMID 3470899. 
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