Cathinones are differentiated by their ketone substitution within the beta carbon of the amphetamine skeleton, this means They're β-keto-amphetamines. 3-MMC has two methyl substitutions on its cathinone skeleton, just one at R3 of the phenyl ring, as well as a 2nd at the nitrogen group RN.Mephedrone. "Not for human use. For complex use only. Purit