Research Article

Synthesis of stable isotopes of auxinic herbicides 4-amino-3,5,6-trichloropicolinic acid and 4-amino-3,6-dichloropicolinic acid

  1. Peter L. Johnson*,
  2. Norman R. Pearson,
  3. Bert Schuster,
  4. Jeremy Cobb

Article first published online: 23 JUN 2009

DOI: 10.1002/jlcr.1613

Issue

Journal of Labelled Compounds and Radiopharmaceuticals

Journal of Labelled Compounds and Radiopharmaceuticals

Volume 52, Issue 9, pages 382–386, July 2009

Additional Information

How to Cite

Johnson, P. L., Pearson, N. R., Schuster, B. and Cobb, J. (2009), Synthesis of stable isotopes of auxinic herbicides 4-amino-3,5,6-trichloropicolinic acid and 4-amino-3,6-dichloropicolinic acid. Journal of Labelled Compounds and Radiopharmaceuticals, 52: 382–386. doi: 10.1002/jlcr.1613

Author Information

  1. Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46268, USA

*Dow AgroSciences, 9330 Zionsville Road, Indianapolis, IN 46258, USA

Publication History

  1. Issue published online: 11 AUG 2009
  2. Article first published online: 23 JUN 2009
  3. Manuscript Accepted: 2 MAY 2009
  4. Manuscript Revised: 1 APR 2009
  5. Manuscript Received: 22 DEC 2008

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Keywords:

  • pentachloropyridine-1-15N-2, 6-13C2;
  • 4-amino-3, 5, 6-trichloropicolinic acid-1-15N-2, 6-13C2;
  • picloram-1-15N-2, 6-13C2;
  • 4-amino-3;
  • 6-dichloropicolinic acid-1-15N-2, 6-13C2;
  • aminopyralid-1-15N-2, 6-13C2;
  • 4-amino-3, 6-dichloropicolinic acid-1-15N-2, 6-13C2-5-2H;
  • aminopyralid-1-15N-2, 6-13C2-5-2H;
  • stable isotope

Graphical Abstract

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Pentachloropyridine-1-15N-2,6-13C2 was prepared in three steps from 1,3-dibromopropane and K13C15N. Isotopically labeled pentachloropyridine served as a key intermediate in the multi-step synthesis of stable isotopes of auxinic herbicides 4-amino-3,5,6-trichloropicolinic acid and 4-amino-3,6-dichloropicolinic acid. Copyright © 2009 John Wiley & Sons, Ltd.

Abstract

Pentachloropyridine serves as a key intermediate in the synthesis of 4-amino-3,5,6-trichloropicolinic acid (picloram) and 4-amino-3,6-dichloropicolinic acid (aminopyralid). An M+3 stable isotope of pentachloropyridine (1, pentachloropyridine-1-15N-2,6-13C2) was prepared from K13C15N. Isotopically labeled pentachloropyridine was then carried through a seven-step synthesis to give an M+3 stable isotope of 4-amino-3,5,6-trichloropicolinic acid (2, picloram-1-15N-2,6-13C2) in an overall yield of 42%. The chlorine atom in the 5-position of 2 was selectively removed via electrochemical reduction. Carrying out the electrochemical reduction in water provided an M+3 stable isotope of 4-amino-3,6-dichloropicolinic acid (3, aminopyralid-1-15N-2,6-13C2), whereas conducting the reduction in deuterium oxide produced an M+4 stable isotope (4, aminopyralid-1-15N-2,6-13C2-5-2H). Copyright © 2009 John Wiley & Sons, Ltd.

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