“…Unimolecular dissociations of simple enol cation‐radicals, e.g. ethenol (acetaldehyde enol),8–16 1‐propen‐1‐ol (propionaldehyde enol),17–22 1‐propen‐2‐ol (acetone enol),23–28 butene‐2‐ols (methyl ethyl ketone enols),29–35 buta‐1,3‐dien‐2‐ol (methyl vinyl ketone enol),36 buta‐1,3‐dien‐1‐ol (crotonaldehyde enol),37 but‐1‐en‐3‐yne‐2‐ol38 and 1‐phenylethen‐1‐ol (acetophenone enol)39–41 have been studied in detail previously using a variety of ion chemistry methods, as reviewed. 6,7 Enol cation‐radicals derived from carboxylic acids and esters, such as 1,1‐dihydroxyethene (enol of acetic acid),42–48 1‐hydroxy‐1‐methoxyethene (enol of methyl acetate)49–57 and 1‐hydroxy‐1‐ethoxyethene (enol of ethyl acetate),58 have also been studied and found to have distinct chemistries in the gas phase.…”