Tin(II) hydroxide, Sn(OH)2, also known as stannous hydroxide, is a chemical compound of tin in the +2 . Pure Sn(OH)2 is prepared by reacting for example (CH3)3SnOH with SnCl2 in an aprotic solvent:
- 2Me3SnOH + SnCl2 → Sn(OH)2 + 2Me3SnCl
There had been confusion as it had been believed that Sn(OH)2 was precipitated when a tin(II) salt is reacted with an alkali hydroxide such as NaOH, but this product was determined analytically to be hydrated tin(II) oxide, being either 5SnO.2H2O or 3SnO.H2O, The structure of pure Sn(OH)2 is not known.
Stannous hydroxide is easily oxidized to stannic acid (Sn(OH)4) by air since tin is often found in oxidation state +4.