Ethanol, the alcohol in wine and beer, oxidises in two steps: first to ethanal, an aldehyde, and then to ethanoic acid, the acid in vinegar. Its two carbon atoms stay joined the whole way.
These are the two moves from the ladder in the last section, made by the end carbon of a two-carbon chain. The carbon holding the -OH loses one hydrogen and the -OH loses its own, which makes the C=O of ethanal. Then an oxygen atom joins between the C=O carbon and its last hydrogen, which makes the -COOH group of the acid.
Wine into vinegar
Leave an open bottle of wine for a few weeks and it turns sour. Bacteria called Acetobacter, common on fruit, use oxygen from the air to oxidise the ethanol to ethanoic acid: C₂H₅OH + O₂ → CH₃COOH + H₂O.
Vinegar makers do this on purpose: wine vinegar starts as wine, and cider vinegar as cider. The bacteria grow as a jelly-like layer on top of the liquid, where they can reach the air. Vinegar makers call it the mother of vinegar.
Inside your liver
Your liver takes ethanol out of the blood in the same two steps. Enzymes are the proteins that speed up the chemistry in your body. One liver enzyme oxidises ethanol to ethanal, and a second oxidises the ethanal to ethanoic acid. Like any acid, ethanoic acid gives away an H⁺. In blood, at a pH of about 7.4, nearly all of it does, so the liver's product is the ethanoate ion. Your cells then break the ethanoate down for energy, and its carbon atoms leave your body as carbon dioxide in your breath.
Ethanal is more toxic than ethanol. Some people have a slow version of the second enzyme, so ethanal builds up in their blood and their face turns red after a small drink.
Where oxidation stops
Propan-2-ol, the alcohol in many hand sanitisers, has its -OH on the middle carbon, and that carbon holds just one hydrogen. Oxidation takes that hydrogen and the one on the -OH, and the C=O forms in the middle of the chain. The product is propanone (acetone), a ketone.
The middle carbon of propanone has no hydrogen left to lose. To go one step further, it would have to give up a bond to one of its two carbons, and gentle oxidation keeps C–C bonds whole. So an alcohol with its -OH at the end of a chain oxidises on to an acid, and an alcohol with its -OH on a middle carbon that holds a hydrogen stops at a ketone.