Cathinones are differentiated by their ketone substitution around the beta carbon on the amphetamine skeleton, this means They're ?-keto-amphetamines. 3-MMC has two methyl substitutions on its cathinone skeleton, 1 at R3 on the phenyl ring, and a second on the nitrogen group RN.Mephedrone. "Not for human usage. For specialized use only. Purity: nin