2-Propenoic acid, 2-methyl-

• Formula: C₄H₆O₂
• Molecular weight: 86.0892
• IUPAC Standard InChI: InChI=1S/C4H6O2/c1-3(2)4(5)6/h1H2,2H3,(H,5,6) Copy

  
• IUPAC Standard InChIKey: CERQOIWHTDAKMF-UHFFFAOYSA-N Copy
• CAS Registry Number: 79-41-4
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  View 3d structure (requires JavaScript / HTML 5)
• Other names: Methacrylic acid; α-Methylacrylic acid; Methylacrylic acid; 2-Methyl-2-propenoic acid; 2-Methylacrylic acid; CH2=C(CH3)COOH; 2-Methylpropenoic acid; Methacrylic acid glacial; α-Methacrylic acid; Acrylic acid, 2-methyl-; Propionic acid, 2-methylene-; Kyselina methakrylova; NSC 7393
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Condensed phase thermochemistry data
  • Phase change data
  • Reaction thermochemistry data
  • IR Spectrum
  • UV/Visible spectrum
  • Gas Chromatography
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
  • Gas phase ion energetics data
  • Mass spectrum (electron ionization)
• Options:
  • Switch to calorie-based units

Condensed phase thermochemistry data

Go To: Top, Phase change data, Reaction thermochemistry data, IR Spectrum, UV/Visible spectrum, Gas Chromatography, NIST Free Links, NIST Subscription Links, 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:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Constant pressure heat capacity of liquid

Phase change data

Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, IR Spectrum, UV/Visible spectrum, Gas Chromatography, NIST Free Links, NIST Subscription Links, 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:
BS - Robert L. Brown and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.
AC - William E. Acree, Jr., James S. Chickos

Enthalpy of vaporization

Antoine Equation Parameters

log₁₀(P) = A − (B / (T + C))
    P = vapor pressure (bar)
    T = temperature (K)

View plot Requires a JavaScript / HTML 5 canvas capable browser.

Enthalpy of fusion

Entropy of fusion

Reaction thermochemistry data

Go To: Top, Condensed phase thermochemistry data, Phase change data, IR Spectrum, UV/Visible spectrum, Gas Chromatography, NIST Free Links, NIST Subscription Links, 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
ALS - 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

C₄H₅O₂^- +  =

By formula: C₄H₅O₂^- + H⁺ = C₄H₆O₂

 +  =

By formula: H₂ + C₄H₆O₂ = C₄H₈O₂

IR Spectrum

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, UV/Visible spectrum, Gas Chromatography, NIST Free Links, NIST Subscription Links, References, Notes

Data compiled by: Coblentz Society, Inc.

• SOLUTION (5% IN CCl4 FOR 3800-1300, 5% IN CS2 FOR 1300-650, AND 5% IN CCl4 FOR 650-240 CM^-1) VERSUS SOLVENT; PERKIN-ELMER 521 (GRATING); DIGITIZED BY NIST FROM HARD COPY (FROM TWO SEGMENTS); 4 cm^-1 resolution

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

• gas

UV/Visible spectrum

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, Gas Chromatography, NIST Free Links, NIST Subscription Links, 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

Gas Chromatography

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, UV/Visible spectrum, NIST Free Links, NIST Subscription Links, 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

Normal alkane RI, non-polar column, temperature ramp

View large format table.

References

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, UV/Visible spectrum, Gas Chromatography, NIST Free Links, NIST Subscription Links, Notes

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

Van-chin-syan, Kochubei, et al., 1996
Van-chin-syan, Yu.Ya.; Kochubei, V.V.; Sergeev, V.V.; Raevskii, Yu.A.; Gerasimchuk, S.I.; Kotovich, Kh.Z., Thermodynamic properties of some acids and aldehydes of the acrylic series, Sov. J. Chem. Phys. (Engl. Transl.), 1996, 70, 1789-1794, In original 1932. [all data]

Lebedeva, Gutner, et al., 1976
Lebedeva, N.D.; Gutner, N.M.; Kiseleva, N.N., Correlation of the departures from additivity in the enthalpies of formation of ethylene and benzene derivatives with the σ_p constants, J. Org. Chem. USSR (Engl. Transl.), 1976, 12, 1594-1597. [all data]

Karabaev, Abduzhaminov, et al., 1985
Karabaev, M.; Abduzhaminov, T.P.; Saidov, A.A.; Igamberdyev, Kh.T., Thermophysical properties of liquid methacrylic acid and its simple esters, Izv. Akad. Nauk Uzb. SSR, Ser. Fiz.-Mat. Nauk, 1985, (4), 71-74. [all data]

Karabaev, Saidov, et al., 1985
Karabaev, M.; Saidov, A.A.; Abduzhaminov, T.P.; Kenisarin, M.M., Heat capacity and molecular kinetic processes of condensed phase acrylates and methacrylates, Izv. Akad. Nauk UzSSR, Ser. Fiz.-Math., 1985, (6), 51-54. [all data]

Weast and Grasselli, 1989
CRC Handbook of Data on Organic Compounds, 2nd Editon, Weast,R.C and Grasselli, J.G., ed(s)., CRC Press, Inc., Boca Raton, FL, 1989, 1. [all data]

D'Souza and Teja, 1987
D'Souza, R.; Teja, A.S., The prediction of the vapor pressures of carboxylic acids, Chem. Eng. Commun., 1987, 61, 13. [all data]

Van-Chin-Syan, Kochubei, et al., 1996
Van-Chin-Syan, Yu.Ya.; Kochubei, V.V.; Sergeev, V.V.; Raevskii, Yu.A.; Gerasimchuk, S.I.; Kotovich, Kh.Z., Thermodynamic properties of some acrylic-series acids and aldehydes, Zh. Fiz. Khim., 1996, 70, 11, 1932. [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [all data]

Stull, 1947
Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

Karabaev, Abduzhaminov, et al., 1985, 2
Karabaev, M.K.; Abduzhaminov, T.P.; Kenisarin, M.M.; Saidov, A.A., Thermodynamics of the crystal-liquid phase transition in acrylates and methacrylates, Izv. Akad. Nauk Uzb. SSR, Ser. Fiz.-Mat. Nauk, 1985, (5), 74-77. [all data]

Domalski and Hearing, 1996
Domalski, Eugene S.; Hearing, Elizabeth D., Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III, J. Phys. Chem. Ref. Data, 1996, 25, 1, 1, https://doi.org/10.1063/1.555985 . [all data]

Graul, Schnute, et al., 1990
Graul, S.T.; Schnute, M.E.; Squires, R.R., Gas-Phase Acidities of Carboxylic Acids and Alcohols from Collision-Induced Dissociation of Dimer Cluster Ions, Int. J. Mass Spectrom. Ion Proc., 1990, 96, 2, 181, https://doi.org/10.1016/0168-1176(90)87028-F . [all data]

Skinner and Snelson, 1959
Skinner, H.A.; Snelson, A., Heats of hydrogenation Part 3., Trans. Faraday Soc., 1959, 55, 405-407. [all data]

Fihtengolts, et al., 1969
Fihtengolts, V.S., et al., Atlas of UV Absorption Spectra of Substances Used in Synthetic Rubbers Manufacture, 1969, 13. [all data]

Meynier, Novelli, et al., 1999
Meynier, A.; Novelli, E.; Chissolinim, R.; Zanardi, E.; Gandemer, G., Volatile compounds of commercial Milano salami, Meat Sci., 1999, 51, 2, 175-183, https://doi.org/10.1016/S0309-1740(98)00122-3 . [all data]

Notes

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, IR Spectrum, UV/Visible spectrum, Gas Chromatography, NIST Free Links, NIST Subscription Links, References

• Symbols used in this document:
  

  Cp,liquid	Constant pressure heat capacity of liquid
  Pc	Critical pressure
  Tboil	Boiling point
  Tc	Critical temperature
  Tfus	Fusion (melting) point
  ΔcH°liquid	Enthalpy of combustion of liquid at standard conditions
  ΔfH°liquid	Enthalpy of formation of liquid at standard conditions
  ΔfusH	Enthalpy of fusion
  ΔfusS	Entropy of fusion
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔvapH	Enthalpy of vaporization
  ΔvapH°	Enthalpy of vaporization 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.