Retro Diels-Alder reaction (RDA reaction)
In organic reactions, it is caused by the Diels-Alder reaction, that is, 1,3-butadiene Condensation with ethylene produces a six-membered cyclic alkene compound. What appears in the mass spectrum is its reverse reaction (RDA reaction), which is the cleavage of a six-membered ring olefin compound to generate a diene compound and ethylene molecules.
The reverse Diels-Alder reaction is particularly important in the structure determination of many compounds. The ion peaks produced by the RDA reaction can often be seen in the mass spectra of alicyclic compounds with double bonds, alkaloids, terpenes, steroids and flavonoids. The RDA reaction uses double bonds as the starting point for the cleavage reaction.