Dehydroacetic Acid

• Formula: C₈H₈O₄
• Molecular weight: 168.1467
• IUPAC Standard InChI: InChI=1S/C8H8O4/c1-4-3-6(10)7(5(2)9)8(11)12-4/h3,7H,1-2H3 Copy

  
• IUPAC Standard InChIKey: PGRHXDWITVMQBC-UHFFFAOYSA-N Copy
• CAS Registry Number: 520-45-6
• Chemical structure:
  This structure is also available as a 2d Mol file
• Other names: 2H-Pyran-2,4(3H)-dione, 3-acetyl-6-methyl-; Dehydracetic acid; DHA; DHS; 3-Acetyl-6-Methyldihydropyrandione-2,4(3H); 4-Hexenoic acid, 2-acetyl-5-hydroxy-3-oxo-, δ-lactone; Methylacetopyronone; 2-Acetyl-5-hydroxy-3-oxo-4-hexenoic acid, δ-lactone; 3-Acetyl-6-methyl-2,4(3H)-pyrandione; 3-Acetyl-6-methyl-2H-pyran-2,4(3H)-dione; 3-Acetyl-6-methylpyrandione-2,4; 3-Acetyl-4-hydroxy-6-methyl-2H-pyran-2-one; 3-Acetyl-6-methyl-2H-pyran-2,4(3H)-dione, enol form; Kyselina dehydroacetova; DHAA; 3-Acetyl-6-methyl-pyran-2,4-dione; 3-Acetyl-6-methyl-2H-pyran-2,4(3H)-dione, ion(1-); 3-Acetyl-6-methyl-2,3-dihydropyran-2,4-dione; Acetic acid, dehydro-; Biocide 470F; NSC 8770
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Reaction thermochemistry data
  • Mass spectrum (electron ionization)
  • UV/Visible spectrum
  • References
  • Notes
• Other data available:
  • Phase change data
• Options:
  • Switch to calorie-based units

Reaction thermochemistry data

Go To: Top, Mass spectrum (electron ionization), UV/Visible spectrum, 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: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

2 =

By formula: 2C₄H₄O₂ = C₈H₈O₄

Mass spectrum (electron ionization)

Go To: Top, Reaction thermochemistry data, UV/Visible spectrum, 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

UV/Visible spectrum

Go To: Top, Reaction thermochemistry 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 by: Victor Talrose, Alexander N. Yermakov, Alexy A. Usov, Antonina A. Goncharova, Axlexander N. Leskin, Natalia A. Messineva, Natalia V. Trusova, Margarita V. Efimkina

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, Reaction thermochemistry data, Mass spectrum (electron ionization), UV/Visible spectrum, Notes

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

Lopatin, Popov, et al., 1992
Lopatin, E.B.; Popov, V.V.; Epshtein, N.A.; Mikhaleva, L.M.; Makarov, Yu.N., Kinetic and thermochemical characteristics of diketene-based reactions, Khim.-Farm. Zh., 1992, 26, 76-78. [all data]

Berson, 1952
Berson, J.A., J. Am. Chem. Soc., 1952, 74, 5172. [all data]

Notes

Go To: Top, Reaction thermochemistry data, Mass spectrum (electron ionization), UV/Visible spectrum, References

• Symbols used in this document:
  

  ΔrH°	Enthalpy of reaction 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.

© 2026 by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Copyright for NIST Standard Reference Data is governed by the Standard Reference Data Act.