Silver(I) Oxide

Introduction

Silver(I) oxide (Ag₂O) has been known for several centuries, and it is still widely used in synthetic chemistry, including in novel strategies. Ag₂O is a black powder that is prepared by the reaction of aqueous silver nitrate and hydroxide salts (eq. 1, Scheme [1]).[1] However, thanks to its stability and low cost, organic chemists most frequently purchase it from commercial suppliers. This reagent has many applications: it can act as a base – due to the presence of oxide –, as an oxidant – due to its easy reduction to metallic silver –, as an halogen scavenger – due to the precipitation of silver halides –, or as a source of silver ion, particularly useful for organometallics preparation.

Ag₂O is poorly soluble in all common solvents including water. It is however readily soluble in ammonia, leading the Tollens’ reagent[2] (eq. 2, Scheme [1]) which possesses a historical importance in the development of organic chemistry. This also illustrates the fact that (as for other metal-based reagents), properties of Ag₂O may depend on the formation of complexes in the reaction medium.

Scheme 1Preparation of silver oxide and Tollens’ reagent

• References

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