>>12206414it's confusing b/c 'hydroxyethylene' itself is an enol, in equilibrium with (the more stable) acetaldehyde.
there's no enol in the structures posted in the thread.
condsider EDTA - commonly known as ethylenediamine tetraacetic acid: here 'ethylene' refers to the subunit -CH2CH2-, which has no double bond. This is the two carbon version of 'methylene' -CH2-, and the style of naming that is relevant to the thread.
