Propanoic acid, 2-methyl-

• Formula: C₄H₈O₂
• Molecular weight: 88.1051
• IUPAC Standard InChI: InChI=1S/C4H8O2/c1-3(2)4(5)6/h3H,1-2H3,(H,5,6) Copy

  
• IUPAC Standard InChIKey: KQNPFQTWMSNSAP-UHFFFAOYSA-N Copy
• CAS Registry Number: 79-31-2
• 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: Isobutyric acid; α-Methylpropanoic acid; α-Methylpropionic acid; Dimethylacetic acid; Isobutanoic acid; Isopropylformic acid; 2-Methylpropanoic acid; 2-Methylpropionic acid; iso-C3H7COOH; Acetic acid, dimethyl-; Cenex RP b2; Propionic acid, 2-methyl-; Tenox IBP 2; Kyselina isomaselna; UN 2529; Methylpropanoic acid; Methylpropionic acid; 2-Propanecarboxylic acid; i-Butyric acid; NSC 62780
• 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
  • Henry's Law data
  • Gas phase ion energetics data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • References
  • Notes
• Other data available:
  • Ion clustering data
  • Gas Chromatography
• Data at other public NIST sites:
  • Gas Phase Kinetics Database
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Condensed phase thermochemistry data

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

Data compiled by: Eugene S. Domalski and Elizabeth D. Hearing

Constant pressure heat capacity of liquid

Phase change data

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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
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Enthalpy of vaporization

Antoine Equation Parameters

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

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Reaction thermochemistry data

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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
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
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

 +  = ( • )

By formula: I^- + C₄H₈O₂ = (I^- • C₄H₈O₂)

 +  = ( • )

By formula: C₄H₇O₂^- + C₄H₈O₂ = (C₄H₇O₂^- • C₄H₈O₂)

 +  =

By formula: C₄H₇O₂^- + H⁺ = C₄H₈O₂

 +  =

By formula: H₂ + C₄H₆O₂ = C₄H₈O₂

 +  = 2

By formula: H₂O + C₈H₁₄O₃ = 2C₄H₈O₂

 +  =  + 

By formula: C₅H₁₀O₂ + H₂O = CH₄O + C₄H₈O₂

Henry's Law data

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

Data compiled by: Rolf Sander

Henry's Law constant (water solution)

k_H(T) = k°_H exp(d(ln(k_H))/d(1/T) ((1/T) - 1/(298.15 K)))
k°_H = Henry's law constant for solubility in water at 298.15 K (mol/(kg*bar))
d(ln(k_H))/d(1/T) = Temperature dependence constant (K)

Gas phase ion energetics data

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

Data evaluated as indicated in comments:
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron
LL - Sharon G. Lias and Joel F. Liebman

View reactions leading to C₄H₈O₂⁺ (ion structure unspecified)

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

 +  =

By formula: C₄H₇O₂^- + H⁺ = C₄H₈O₂

IR Spectrum

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Data compiled by: Coblentz Society, Inc.

• LIQUID; Not specified, most likely a prism, grating, or hybrid spectrometer.; DIGITIZED BY NIST FROM HARD COPY; 4 cm^-1 resolution
• SOLUTION (2% IN CCl4 FOR 3800-1300, 2% IN CS2 FOR 1300-650, 2% IN CCl4 FOR 650-250 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

Mass spectrum (electron ionization)

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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

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Additional Data

References

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, IR Spectrum, 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.

Biros, Sikora, et al., 1982
Biros, J.; Sikora, A.; Zivny, A.; Pouchly, J., Heat capacity of monomer models of some hydrophilic polymers in aqueous solution from 20° to 60°C, Collect Czech. Chem. Commun., 1982, 47(10), 2692-2701. [all data]

Konicek and Wadso, 1971
Konicek, J.; Wadso, I., Thermochemical properties of some carboxylic acids, amines and N-substituted amides in aqueous solution, Acta Chem. Scand., 1971, 25, 1541-1551. [all data]

von Reis, 1881
von Reis, M.A., Die specifische Wärme flüssiger organischer Verbindungen und ihre Beziehung zu deren Moleculargewicht, Ann. Physik [3], 1881, 13, 447-464. [all data]

Ambrose and Ghiassee, 1987
Ambrose, D.; Ghiassee, N.B., Vapor Pressures and Critical Temperatures and Critical Pressures of Some Alkanoic Acids: C1 to C10, J. Chem. Thermodyn., 1987, 19, 505. [all data]

Brown, 1906
Brown, J.C., The critical temperature and value of ml/theta of some carbon compounds, J. Chem. Soc., Trans., 1906, 89, 311. [all data]

Verevkin, 2000
Verevkin, S.P., Measurement and Prediction of the Monocarboxylic Acids Thermochemical Properties, J. Chem. Eng. Data, 2000, 45, 5, 953-960, https://doi.org/10.1021/je990282m . [all data]

Majer and Svoboda, 1985
Majer, V.; Svoboda, V., Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation, Blackwell Scientific Publications, Oxford, 1985, 300. [all data]

Kruif and Oonk, 1979
Kruif, C.G.; Oonk, H.A.J., Enthalpies of vaporization and vapour pressures of seven aliphatic carboxylic acids, J. Chem. Thermodyn., 1979, 11, 287-290. [all data]

Konicek, Wadsö, et al., 1970
Konicek, Jiri; Wadsö, Ingemar; Munch-Petersen, J.; Ohlson, Ragnar; Shimizu, Akira, Enthalpies of Vaporization of Organic Compounds. VII. Some Carboxylic Acids., Acta Chem. Scand., 1970, 24, 2612-2616, https://doi.org/10.3891/acta.chem.scand.24-2612 . [all data]

Clifford, Ramjugernath, et al., 2004
Clifford, Scott L.; Ramjugernath, Deresh; Raal, J. David, Subatmospheric Vapor Pressure Curves for Propionic Acid, Butyric Acid, Isobutyric Acid, Valeric Acid, Isovaleric Acid, Hexanoic Acid, and Heptanoic Acid, J. Chem. Eng. Data, 2004, 49, 5, 1189-1192, https://doi.org/10.1021/je034180e . [all data]

Ambrose and Ghiassee, 1987, 2
Ambrose, D.; Ghiassee, N.B., Vapour pressures and critical temperatures and critical pressures of some alkanoic acids: C1 to C10, The Journal of Chemical Thermodynamics, 1987, 19, 5, 505-519, https://doi.org/10.1016/0021-9614(87)90147-9 . [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]

Kahlbaum, 1883
Kahlbaum, Georg W.A., Ueber die Abhängigkeit der Siedetemperatur vom Luftdruck, Ber. Dtsch. Chem. Ges., 1883, 16, 2, 2476-2484, https://doi.org/10.1002/cber.188301602178 . [all data]

Caldwell and Kebarle, 1984
Caldwell, G.; Kebarle, P., Binding energies and structural effects in halide anion-ROH and -RCOOH complexes from gas phase equilibria measurements, J. Am. Chem. Soc., 1984, 106, 967. [all data]

Meot-Ner and Sieck, 1986
Meot-Ner, M.; Sieck, L.W., The ionic hydrogen bond and ion solvation. 5. OH...O^- bonds. Gas phase solvation and clustering of alkoxide and carboxylate anions, J. Am. Chem. Soc., 1986, 108, 7525. [all data]

Caldwell, Renneboog, et al., 1989
Caldwell, G.; Renneboog, R.; Kebarle, P., Gas Phase Acidities of Aliphatic Carboxylic Acids, Based on Measurements of Proton Transfer Equilibria, Can. J. Chem., 1989, 67, 4, 661, https://doi.org/10.1139/v89-092 . [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]

Conn, Kistiakowsky, et al., 1942
Conn, J.B.; Kistiakowsky, G.B.; Roberts, R.M.; Smith, E.A., Heats of organic reactions. XIII. Heats of hydrolysis of some acid anhydrides, J. Am. Chem. Soc., 1942, 64, 1747-17. [all data]

Guthrie and Cullimore, 1980
Guthrie, J.P.; Cullimore, P.A., Effect of the acyl substituent on the equilibrium constant for hydration of esters, Can. J. Chem., 1980, 58, 1281-1294. [all data]

Holmes and Lossing, 1980
Holmes, J.L.; Lossing, F.P., Gas-phase heats of formation of keto and enol ions of carbonyl compounds., J. Am. Chem. Soc., 1980, 102, 1591. [all data]

Watanabe, Yokoyama, et al., 1974
Watanabe, I.; Yokoyama, Y.; Ikeda, S., Vibrational structures in the He(I) photoelectron spectra of carboxylic acids, Bull. Chem. Soc. Jpn., 1974, 47, 627. [all data]

Watanabe, Yokoyama, et al., 1973
Watanabe, I.; Yokoyama, Y.; Ikeda, S., Lone pair ionization potentials of carboxylic acids determined by He(I) photoelectron spectroscopy, Bull. Chem. Soc. Jpn., 1973, 46, 1959. [all data]

Thomas, 1972
Thomas, R.K., Photoelectron spectroscopy of hydrogen-bonded systems: spectra of monomers, dimers and mixed complexes of carboxylic acides, Proc. R. Soc. London A:, 1972, 331, 249. [all data]

Watanabe, Nakayama, et al., 1962
Watanabe, K.; Nakayama, T.; Mottl, J., Ionization potentials of some molecules, J. Quant. Spectry. Radiative Transfer, 1962, 2, 369. [all data]

Sustmann and Trill, 1972
Sustmann, R.; Trill, H., Photoelektronenspektroskopische Bestimmung von Substituenten-Effekten. II. α,β-ungesattigte Carbonester, Tetrahedron Lett., 1972, 42, 4271. [all data]

Holmes, Lossing, et al., 1991
Holmes, J.L.; Lossing, F.P.; Mayer, P.M., Heats of formation of oxygen-containing organic free radicals from appearance energy measurements, J. Am. Chem. Soc., 1991, 113, 9723. [all data]

Notes

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, IR Spectrum, Mass spectrum (electron ionization), References

• Symbols used in this document:
  

  AE	Appearance energy
  Cp,liquid	Constant pressure heat capacity of liquid
  IE (evaluated)	Recommended ionization energy
  Pc	Critical pressure
  Tboil	Boiling point
  Tc	Critical temperature
  Tfus	Fusion (melting) point
  d(ln(kH))/d(1/T)	Temperature dependence parameter for Henry's Law constant
  k°H	Henry's Law constant at 298.15K
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔrS°	Entropy 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
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