Silver acetate

Silver acetate
Names
Other names
Acetic acid, silver (1+) salt
Silver ethanoate
Identifiers
563-63-3 YesY
3D model (Jmol) Interactive image
ChemSpider 10772 YesY
ECHA InfoCard 100.008.414
EC Number 209-254-9
PubChem 11246
RTECS number AJ4100000
UNII 19PPS85F9H YesY
Properties
AgC2H3O2
Molar mass 166.912 g/mol
Appearance white to slightly grayish powder
slightly acidic odor
Density 3.26 g/cm3, solid
Boiling point decomposes at 220 °C
1.02 g/100 mL(20 °C)
Hazards
not listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine 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
0
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Silver acetate is an inorganic compound with the empirical formula CH3CO2Ag (or AgC2H3O2). It is a photosensitive, white, crystalline solid. It is a useful reagent in the laboratory as a source of silver ions lacking an oxidizing anion. It has been used in some antismoking drugs.

Synthesis and structure

Silver acetate can be synthesized by the reaction of acetic acid and silver carbonate at 45–60 °C. After allowing cooling to room temperature, the solid product precipitates.[1]

2 CH3CO2H + Ag2CO3 → 2 AgO2CCH3 + H2O + CO2

It can also be precipitated from concentrated aqueous solutions of silver nitrate by treatment with a solution of sodium acetate.

The structure of silver acetate consists of 8-membered Ag2O4C2 rings formed by a pair of acetate ligands bridging a pair of silver centres.[2]

Reactions

Thermal Decomposition

Solid silver acetate decomposes with heat to make silver particles and various gases, depending on the atmosphere present, and decomposes at slightly lower temperatures with increasing humidity. In air, the reaction mainly goes by the following:

4 CH3CO2Ag + 7 O2 → 4 Ag + 8 CO2 + 6 H2O

Carbonylation

Silver acetate, when combined with carbon monoxide (CO), can induce the carbonylation of primary and secondary amines. Other silver salts can be used but the acetate gives the best yield.

2 R2NH + 2 AgOAc + CO → [R2N]2CO + 2 HOAc + 2 Ag

Hydrogenation

A solution of silver acetate in pyridine absorbs hydrogen, producing metallic silver:[3]

2 CH3CO2Ag + H2 → 2 Ag + 2 CH3CO2H

Direct ortho-arylation

Silver acetate is a useful reagent for direct ortho-arylation (to install two adjacent substituents on an aromatic ring) for of benzylamines and N-methylbenzylamines. The reaction is palladium-catalized and requires a slight excess of silver acetate.[4] This reaction is shorter than previous ortho-arylation methods.

Oxidative dehalogenation

Silver acetate can be used to convert certain organohalogen compounds into alcohols. It may be used, in spite of its high cost, in instances where a mild and selective reagent is desired.

Woodward cis-hydroxylation

Silver acetate in combination with iodine forms the basis of the Woodward cis-hydroxylation. This reaction selectively converts an alkenes into a cis-diols.[5]

Uses

In the health field, silver acetate-containing products have been used in gum, spray, and lozenges to deter smokers from smoking. The silver in these products, when mixed with smoke, creates an unpleasant metallic taste in the smoker's mouth, thus deterring them from smoking. Lozenges containing 2.5 mg of silver acetate showed "modest efficacy" on 500 adult smokers tested over a three-month period. However, over a period of 12 months, prevention failed. In 1974, silver acetate was first introduced in Europe as an over-the-counter smoking-deterrent lozenge (Repaton) and then three years later as a chewing gum (Tabmint).[6]

Safety

The LD50 of silver acetate in mice is 36.7 mg/kg. Low doses of silver acetate in mice produced hyper-excitability, ataxia, central nervous system depression, labored breathing, and even death.[7] The U.S. FDA recommends that silver acetate intake be limited to 756 mg over a short period of time; excessive intake may cause argyria.[6][8]

References

  1. ↑ Logvinenko, V.; Polunina, O.; Mikhailov, Yu; Mikhailov, K.; Bokhonov, B. (2007). "Study of Thermal Decomposition of Silver Acetate". Journal of Thermal Analysis and Calorimetry. 90 (3): 813–816. doi:10.1007/s10973-006-7883-9.
  2. ↑ Leif P. Olson, David R. Whitcomb, Manju Rajeswaran, Thomas N. Blanton, Barbara J. Stwertka "The Simple Yet Elusive Crystal Structure of Silver Acetate and the Role of the Ag−Ag Bond in the Formation of Silver Nanoparticles during the Thermally Induced Reduction of Silver Carboxylates" Chem. Mater., 2006, volume 18, pp 1667–1674. doi:10.1021/cm052657v
  3. ↑ Wright, Leon; Well, Sol; Mills, G.A. (1955). "Homogeneous Catalytic Hydrogenation III. Activation of Hydrogen by Cuprous and Silver Acetates in Pyridine and Dodecylamine". Journal of Physical Chemistry. 59: 1060–1064. doi:10.1021/j150532a016.
  4. ↑ Lazareva, Anna; Daugulis (2006). "Olafs". Direct Palladium-Catalyzed Ortho-Arylation of Benzylamines. 8: 5211–5213. doi:10.1021/o1061919b.
  5. ↑ Woodward, R. B.; Brutcher, F. V. (January 1958). "cis-Hydroxylation of a Synthetic Steroid Intermediate with Iodine, Silver Acetate and Wet Acetic Acid". Journal of the American Chemical Society. 80 (1): 209–211. doi:10.1021/ja01534a053.
  6. 1 2 Hymowitz, Norman; Eckholdt, Haftan (1996). "Effects of a 2.5-mg Silver Acetate Lozenge on Initial and Long-Term Smoking Cessation". Journal of Preventive Medicine. 25 (5): 537–546. doi:10.1006/pmed.1996.0087. PMID 8888321.
  7. ↑ Horner, Heidi C.; Roebuck, B.D.; Smith, Roger P.; English, Jackson P. (1977). "Acute toxicity of some silver salts of sulfonamides in mice and the efficacy of penicillamine in silver poisoning". Drug and Chemical Toxicology. 6: 267–277.
  8. ↑ E. J. Jensen; E. Schmidt; B. Pedersen; R. Dahl (1991). "Effect on smoking cessation of silver acetate, nicotine and ordinary chewing gum, Influence of smoking history". Psychopharmacology. 104 (4): 470–474. doi:10.1007/BF02245651. PMID 1780416.

Further reading

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