An opened bottle of wine developed into a sour taste and smell of vinegar. Why?
The ethanol (alcohol content) of the wine, is oxidised, by the oxygen in the air into ethanoic acid. Vinegar is dilute acetic acid which is where it gets its smell.
The reaction happens in to stages,
- The ethanol is partially oxidised to ethanal
- The ethanal is further oxidised to ethanoic acid