Oxalic acid

• Formula: C₂H₂O₄
• Molecular weight: 90.0349
• IUPAC Standard InChI: InChI=1S/C2H2O4/c3-1(4)2(5)6/h(H,3,4)(H,5,6) Copy

  
• IUPAC Standard InChIKey: MUBZPKHOEPUJKR-UHFFFAOYSA-N Copy
• CAS Registry Number: 144-62-7
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  The 3d structure may be viewed using Java or Javascript.
• Other names: Ethanedioic acid; Aktisal; Aquisal; Oxiric acid; HOOCCOOH; Acide oxalique; Acido ossalico; Ethanedionic acid; Kyselina stavelova; NCI-C55209; Oxaalzuur; Oxalsaeure; Ethane-1,2-dioic acid; NSC 62774
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Phase change data
  • Gas phase ion energetics data
  • Mass spectrum (electron ionization)
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
  • Condensed phase thermochemistry data
  • Reaction thermochemistry data
  • Henry's Law data
  • UV/Visible spectrum
  • Gas Chromatography
• Data at other public NIST sites:
  • Gas Phase Kinetics Database
  • X-ray Photoelectron Spectroscopy Database, version 5.0
• Options:
  • Switch to SI units

Data at NIST subscription sites:

• NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.

Phase change data

Go To: Top, Gas phase ion energetics data, Mass spectrum (electron ionization), References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
AC - William E. Acree, Jr., James S. Chickos
DH - Eugene S. Domalski and Elizabeth D. Hearing

Enthalpy of sublimation

Enthalpy of phase transition

Entropy of phase transition

Gas phase ion energetics data

Go To: Top, Phase change data, Mass spectrum (electron ionization), References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
B - John E. Bartmess
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
LL - Sharon G. Lias and Joel F. Liebman

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

C₂HO₄^- +  =

By formula: C₂HO₄^- + H⁺ = C₂H₂O₄

Mass spectrum (electron ionization)

Go To: Top, Phase change data, Gas phase ion energetics data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Spectrum

Notice: This spectrum may be better viewed with a Javascript and HTML 5 enabled browser.

For Zoom

1.) Enter the desired X axis range (e.g., 100, 200)

2.) Check here for automatic Y scaling

3.) Press here to zoom

Additional Data

References

Go To: Top, Phase change data, Gas phase ion energetics data, Mass spectrum (electron ionization), Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Wilhoit and Shiao, 1964
Wilhoit, R.C.; Shiao, D., Thermochemistry of Biologically Important Compounds. Heats of Combustion of Solid Organic Acids, J. Chem. Eng. Data, 1964, 9, 595. [all data]

Bradley and Cleasby, 1953
Bradley, R.S.; Cleasby, T.G., The vapour pressure and lattice energy of hydrogen-bonded crystals. Part I. Oxamide, oxamic acid, and rubeanie acid, J. Chem. Soc., 1953, 1681-16. [all data]

Granovskaya, 1947
Granovskaya, A., Russ. J. Phys. Chem., 1947, 21, 967. [all data]

Noyes and Wobbe, 1926
Noyes, W. Albert; Wobbe, Delbert E., THE VAPOR PRESSURE OF ANHYDROUS OXALIC ACID, J. Am. Chem. Soc., 1926, 48, 7, 1882-1887, https://doi.org/10.1021/ja01418a012 . [all data]

Petropavlov, Tsygankova, et al., 1988
Petropavlov, N.N.; Tsygankova, I.G.; Teslenko, L.A., Microcalorimetric investigation of polymorphic transitions in organic crystals, Sov. Phys. Crystallogr., 1988, 33(6), 853-855. [all data]

McGlynn and Meeks, 1976
McGlynn, S.P.; Meeks, J.L., Photoelectron spectra of carbonyls, carbonates, oxalates and esterification effects, J. Electron Spectrosc. Relat. Phenom., 1976, 8, 85. [all data]

Meeks, Arnett, et al., 1975
Meeks, J.L.; Arnett, J.F.; Larson, D.B.; McGlynn, S.P., Photoelectron spectroscopy of carbonyls. Urea, oxamide, oxalic acid and oxamic acid, J. Am. Chem. Soc., 1975, 97, 3905. [all data]

Arnett, Newkome, et al., 1974
Arnett, J.F.; Newkome, G.; Mattice, W.L.; McGlynn, S.P., Excited electronic states of the α-dicarbonyls, J. Am. Chem. Soc., 1974, 96, 4385. [all data]

Chen and Holmes, 1994
Chen, H.; Holmes, J.L., The generation of OC₂O⁺ and OC₂O and a study of ionized OC₃O and C₂O by tandem mass spectrometry, Int. J. Mass Spectrom. Ion Processes, 1994, 133, 111. [all data]

Kumar, Prabhakar, et al., 2005
Kumar, M.R.; Prabhakar, S.; Nagaveni, V.; Vairamani, M., Estimation of gas-phase acidities of a series of dicarboxylic acids by the kinetic method, Rapid Commun. Mass Spectrom., 2005, 19, 8, 1053-1057, https://doi.org/10.1002/rcm.1888 . [all data]

Notes

Go To: Top, Phase change data, Gas phase ion energetics data, Mass spectrum (electron ionization), References

• Symbols used in this document:
  

  AE	Appearance energy
  Tfus	Fusion (melting) point
  ΔHtrs	Enthalpy of phase transition
  ΔStrs	Entropy of phase transition
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔsubH	Enthalpy of sublimation
  ΔsubH°	Enthalpy of sublimation at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
• The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
• Customer support for NIST Standard Reference Data products.