Methylenedioxyphenethylamine (MDxx)

The MDxx compounds are a chemical class of organic compounds derived from the core phenethylamine and amphetamine structures, built around a methylenedioxy bridge, a small ring fused across the 3,4-positions of the benzene ring, which is the feature the "MD" prefix points to. They share this 3,4-methylenedioxy phenyl group attached to an alpha-methyl amphetamine sidechain, differing mainly in the group on the amine nitrogen. Most MDxx compounds act as entactogens, releasing serotonin alongside dopamine and noradrenaline. The methylenedioxy ring is what distinguishes the family from the plain amphetamines and phenethylamines it is otherwise derived from.