Ethylenedioxy  Ethylenedioxy, in chemistry, especially organic chemistry, is a functional group with the structural formula R-O-CH2-CH2-O-R'. It is generally attached to an aromatic ring such as a phenyl, in which case it is called ethylenedioxyphenyl or dihydrobenzodioxine. The ethylenedioxy moiety can be found in the compound EDMA as an example.