Anas ibn Mālik (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) was asked about making vinegar out of an alcoholic drink. He said: 'No.'
Anas ibn Mālik (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) was asked about the ruling on alcohols that were processed until transferred into vinegar, that incident occurred after the prohibition of alcoholic drinks, and he forbade that. Accordingly, if an alcoholic drink is transformed into vinegar in any way or form, it will continue to be prohibited and this will not change its ruling. This covers all possible ways of transforming wine into vinegar such as placing something therein like bread, onion, stone, yeast; moving it from the shade to the sun or vice-versa; or mixing it with another substance. Yet, if it turned into vinegar all by itself without human interference, it would become pure and permissible.