Ortho Effect in the Fragmentation of 2-Acetoxychalcones under Electron Impact

Article abstract of DOI:10.1002/oms.1210190708

2-Acetoxychalcones decompose under electron impact conditions by loss of an acetoxy fragment to form flavylium ions.The effect is restricted to the ortho position and is reduced after hydrogenation of the chalcone double bond.The intense flavylium ion originates as shown by specific labelling with ¹⁸O-from two different fragmentation lines: (a) direct loss of an acetoxy radical by cleavage of the phenolic Ar-O bond and (b) sequential elimination of ketene and a hydroxy radical.