title: Preparation and structural analysis of (±)-threo-ritalinic acid.
abstract: Hydrolysis of the methyl ester (±)-threo-methyl phenidate afforded the free acid in 40% yield, viz. (±)-threo-ritalinic acid, C13H17NO2. Hydrolysis and subsequent crystallization were accomplished at pH values between 5 and 7 to yield colourless prisms which were analysed by X-ray crystallography. Crystals of (±)-threo-ritalinic acid belong to the P21/n space group and form intermolecular hydrogen bonds. An antiperiplanar disposition of the H atoms of the (HOOC-)CH-CHpy group (py is pyridine) was found in both the solid (diffraction analysis) and solution state (NMR analysis). It was also determined that (±)-threo-ritalinic acid conforms to the minimization of negative gauche(+)-gauche(-) interactions.
authors.affiliation: Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology, Wolfgang-Pauli Strasse 10, Zurich 8093, Switzerland.
authors.forename: Sara
authors.initials: S
authors.lastname: Wyss
authors.forename: Irmgard A
authors.initials: IA
authors.lastname: Werner
authors.forename: W Bernd
authors.initials: WB
authors.lastname: Schweizer
authors.forename: Simon M
authors.initials: SM
authors.lastname: Ametamey
authors.forename: Selena
authors.initials: S
authors.lastname: Milicevic Sephton
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008774:Methylphenidate / Q000031:analogs & derivatives* / Q000032:analysis / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D008774:Methylphenidate; C009189:ritalinic acid
keywords: (±)-threo-methyl phenidate; (±)-threo-ritalinic acid; Ritalin®; crystal structure; gauche+–gauche- interactions; hydrolysis