Ritalinic acid is a major metabolite of and synthetic precursor to methylphenidate (Ritalin�) and may be monitored clinically and forensically. �-threo-Ritalinic acid-D10 HCl was synthesized as an analytical reference standard and as a precursor to deuterated �-threo-methylphenidate  in seven steps with a purity of 99% and an isotopic purity ratio of D0/D10 = 0%. The presence of significant amounts of the D9-D7 isomers prompted extensive structure elucidation using 1D and 2D NMR. Additionally, qNMR was used to determine exactly what percentage of hydrogen, and therefore deuterium, is present on each carbon in the molecule. These results suggest that the Pt/C catalyst used in the synthesis also facilitated the exchange of aromatic hydrogens to deuterium creating the undesirable deuterium distribution. This study highlights chemical interactions that factor into the design of stable labeled internal standards for LCMS applications.

Synthesis of [plusmn]-threo-Ritalinic acid-D<sub>10</sub> hydrochloride and deuterium placement determination by qNMR

243rd National Meeting (2012)

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Synthesis of [plusmn]-threo-Ritalinic acid-D10 hydrochloride and deuterium placement determination by qNMR

Synthesis of [plusmn]-threo-Ritalinic acid-D₁₀ hydrochloride and deuterium placement determination by qNMR