METHADONE

Methadone is a fully synthetic opioid belonging to the diphenylheptane class of compounds.

• Chemical name (IUPAC):
  6-(dimethylamino)-4,4-diphenylheptan-3-one
• Molecular formula:
  C₂₁H₂₇NO
• Molar mass:
  309.45 g/mol

Chemical class

• Synthetic opioid
• Diphenylheptane derivative
• Tertiary amine-containing organic compound

Key structural features

• A seven-carbon (heptane) chain
• A ketone group (3-one) on the carbon backbone
• Two phenyl (benzene) rings attached to the same carbon (4,4-diphenyl)
• A dimethylamino group attached to the chain

Functional groups

• Ketone (C=O)
• Tertiary amine [N(CH₃)₂]
• Two aromatic phenyl rings

Stereochemistry

• Contains a single chiral center
• Exists as two enantiomers:
  • (R)-methadone (levomethadone)
  • (S)-methadone
• The R-enantiomer has most of the opioid receptor activity

Pharmacological chemical class

• μ-opioid receptor agonist
• Synthetic opioid analgesic

Structural significance

Unlike opioids such as morphine or oxycodone, methadone does not possess the classic morphinan/phenanthrene ring system. Instead, it belongs to the diphenylheptane family, characterized by:

• A flexible carbon chain
• Two phenyl rings
• A tertiary amine

This makes methadone structurally distinct from many naturally derived and semi-synthetic opioids.

Physical characteristics

• Pure methadone is typically a white crystalline solid
• Commonly encountered as methadone hydrochloride, a more water-soluble salt form
• Stable under normal storage conditions