Silver carbonate explained

Silver carbonate is the chemical compound with the formula Ag₂CO₃. This salt is yellow but typical samples are grayish due to the presence of elemental silver. It is poorly soluble in water, like most transition metal carbonates.

Preparation and reactions

Silver carbonate can be prepared by combining aqueous solutions of sodium carbonate with a deficiency of silver nitrate.

2 AgNO3(aq) + Na2CO3(aq) -> Ag2CO3(s) + 2 NaNO3(aq)Freshly prepared silver carbonate is colourless, but the solid quickly turns yellow.

Silver carbonate reacts with ammonia to give the diamminesilver(I) ([Ag(NH₃)₂]⁺) complex ion. Like other diamminesilver(I) solutions, including Tollen's reagent, there is a possibility that explosive Silver nitride may precipitate out of the solution. Silver nitride was previously known as fulminating silver but due to confusions with silver fulminate it has been discontinued by the IUPAC.^[1]

With hydrofluoric acid, it gives silver fluoride.

The thermal conversion of silver carbonate to silver metal proceeds via formation of silver oxide:^[2]

Ag2CO3 -> Ag2O + CO2

2 Ag2O ->4 Ag + O2

Uses

The principal use of silver carbonate is for the production of silver powder for use in microelectronics. It is reduced with formaldehyde, producing silver free of alkali metals:^[3]

Ag2CO3 + CH2O -> 2 Ag + 2 CO2 + H2

Organic synthesis

Silver carbonate is used as a reagent in organic synthesis.^[4] In the Fétizon oxidation, silver carbonate on Celite^[5] serves as an oxidising agent to form:

• aldehydes from primary alcohols,
• ketones from secondary alcohols,
• keto-alcohols from diols,
• and ketones from hydroxymethyl compounds.

In the Koenigs-Knorr reaction it is used to convert alkyl bromides to the methyl ethers. It is also employed to convert alkyl bromides into alcohols. As a base, it has been used in the Wittig reaction.^[6] and in C-H bond activation.^[7]

Notes and References

1. Book: Brumby . Andreas . Braumann . Peter . Zimmermann . Klaus . Brodeck . Francis . Vandevelde . Thierry . Goia . Dan . Renner . Hermann . Schlamp . Gunter . Zimmermann . Klaus . Weise . Wolfgang . Tews . Peter . Dermann . Klaus . Knodler . Alfons . Schroder . Karl-Heinz . Kempf . Bernd . Luschow . Hans . Peter . Cartrin . Schiele . Rainer . Ullmann's Encyclopedia of Industrial Chemistry . 2008 . 9783527306732 . 49 . 10.1002/14356007.a24_107.pub2 . 2020-12-24.
2. Koga, Nobuyoshi. Shuto Yamada. Tomoyasu Kimura. Thermal Decomposition of Silver Carbonate: Phenomenology and Physicogeometrical Kinetics. The Journal of Physical Chemistry C. 117. 2013. 326–336. 10.1021/jp309655s.
3. Andreas Brumby et al. "Silver, Silver Compounds, and Silver Alloys" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2008.
4. Book: 10.1002/047084289X.rn01865 . Silver(I) Carbonate . Encyclopedia of Reagents for Organic Synthesis . 2001 . Ladd . Carolyn L. . 1–10 . 978-0-470-84289-8 .
5. Book: 10.1002/047084289X.rs014.pub2 . Silver(I) Carbonate on Celite . Encyclopedia of Reagents for Organic Synthesis . 2017 . Fétizon . Marcel . Li . Yiming . Jiang . Xuefeng . 1–19 . 978-0-470-84289-8 .
6. Jedinak, Lukas et al. “Use of Silver Carbonate in the Wittig Reaction.” The Journal of Organic Chemistry 78.23 (2013): 12224–12228 https://doi.org/10.1021/jo401972a.
7. J. Org. Chem., 2018, 83 (16), pp 9312–9321 https://doi.org/10.1021/acs.joc.8b01284.