what chemical process is responsible for the smell of vinegar in an old bottle of aspirin?
28,450 Contributions. The smell of vinegar from an old bottle of aspirin is an indication  that the active ingredient in aspirin, acetylsalicylic acid, has  decomposed. One of the products of the â¦ decomposition of aspirin is  acetic acid, which is the active ingredient in vinegar and what  smells. You should definitely not consume drugs that are past the  expiration date that have decomposed!