Crystal structure of zymonic acid and a redetermination of its precursor, pyruvic acid

Dominik Heger, Alexis J. Eugene, Sean R. Parkin, Marcelo I. Guzman

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The structure of zymonic acid (systematic name: 4-hydroxy-2-methyl-5-oxo-2,5-dihydrofuran-2-carboxylic acid), C6 H6O 5, which had previously eluded crystallographic determination, is presented here for the first time. It forms by intramolecular condensation of parapyruvic acid, which is the product of aldol condensation of pyruvic acid. A redetermination of the crystal structure of pyruvic acid (systematic name: 2-oxopropanoic acid), C3H4O 3, at low temperature (90 K) and with increased precision, is also presented [for the previous structure, see: Harata et al. (1977). Acta Cryst. B33, 210-212]. In zymonic acid, the hydroxylactone ring is close to planar (r.m.s. deviation = 0.0108 Å) and the dihedral angle between the ring and the plane formed by the bonds of the methyl and carboxylic acid carbon atoms to the ring is 88.68 (7)°. The torsion angle of the carboxylic acid group relative to the ring is 12.04 (16)°. The pyruvic acid molecule is almost planar, having a dihedral angle between the carboxylic acid and methyl-ketone groups oF3.95 (6)°. Intermolecular interactions in both crystal structures are dominated by hydrogen bonding. The common R22 (8) hydrogen-bonding motif links carboxylic acid groups on adjacent molecules in both structures. In zymonic acid, this results in dimers about a crystallographic twofold of space group C2/c, which forces the carboxylic acid group to be disordered exactly 50:50, which scrambles the carbonyl and hydroxyl groups and gives an apparent equalization of the C - O bond lengths [1.2568 (16) and 1.2602 (16) Å]. The other hydrogen bonds in zymonic acid (O - H...O and weak C - H...O), link molecules across a21 -screw axis, and generate an R22 (9) motif. These hydrogen-bonding interactions propagate to form extended pleated sheets in the ab plane. Stacking of these zigzag sheets along c involves only van der Waals contacts. In pyruvic acid, inversion-related molecules are linked into R22 (8) dimers, with van der Waals interactions between dimers as the only other intermolecular contacts.

Original languageEnglish
Pages (from-to)858-862
Number of pages5
JournalActa Crystallographica Section E: Crystallographic Communications
StatePublished - 2019

Bibliographical note

Funding Information:
We are thankful for research funding from the National Science Foundation under NSF CAREER award CHE-1255290 to MIG, and the MRI program, grants CHE-0319176 and CHE-1625732. An International Visiting Scholar grant from the College of Arts and Sciences at UK is gratefully acknowledged.

Publisher Copyright:
© 2019 Heger et al.


  • crystal structure
  • hydrogen bonding
  • low temperature
  • pyruvic
  • zymonic

ASJC Scopus subject areas

  • Chemistry (all)
  • Materials Science (all)
  • Condensed Matter Physics


Dive into the research topics of 'Crystal structure of zymonic acid and a redetermination of its precursor, pyruvic acid'. Together they form a unique fingerprint.

Cite this