Mechanistic Re-investigation on Strecker Synthesis of Aminonitrile

Undergraduate #154
Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)

Ryan Johnston - University of the District of Columbia
Co-Author(s): Weixing Li, The Catholic University of America, Washington, DC Xueqing Song, University of the District of Columbia, Washington, DC

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The Strecker reactions have been widely used in the synthesis of amino acids from aldehydes or ketones. Our recent 1H and 13C NMR studies showed that proton NMR and carbon NMR signals for an unknown species have been observed, which was in contradiction with the proposed mechanism in the literature.
For this reason, a systematic NMR investigation was done for the reaction aiming to collect more thermodynamic and kinetic data for the Strecker reaction. Strecker syntheses of aminonitriles were successfully carried out using Methylketone (2-octanone), 4-benzylpiperidone as the model compounds. A precise, fast and comprehensive model was established to monitor the reaction process. It was found that the completion of the reaction varies with the concentration of the amine used. Alpha-aminohydroxy nitrile was identified for the first time in both acidic (ammonium chloride) and basic media (ammonia/ ammonium chloride) as the major intermediate in the reaction. A modified mechanism was proposed for the reaction based on that finding. Future studies will be proposed to investigate the mechanism in the conversion from aminonitriles to aminoacids.

Funder Acknowledgement(s): Financial support from the Science, Technology, Engineering and Mathematics (STEM) Program at UDC is gratefully acknowledged (NSF/HBCU-UP-HRD0928444).

Faculty Advisor: Xueqing Song,