Leucine

• Formula: C₆H₁₃NO₂
• Molecular weight: 131.1729
• IUPAC Standard InChI: InChI=1S/C6H13NO2/c1-4(2)3-5(7)6(8)9/h4-5H,3,7H2,1-2H3,(H,8,9)/t5-/m1/s1 Copy

  
• IUPAC Standard InChIKey: ROHFNLRQFUQHCH-RXMQYKEDSA-N Copy
• CAS Registry Number: 61-90-5
• Chemical structure:
  This structure is also available as a 2d Mol file
• Stereoisomers:
  • Leucine
  • D-Leucine
  • DL-Leucine
• Other names: L-Leucine; Leucine, L-; L-α-Aminoisocaproic acid; α-Amino-γ-methylvaleric acid; (S)-(+)-Leucine; L-(+)-Leucine; Leu; Pentanoic acid, 2-amino-4-methyl-, (S)-; 2-Amino-4-methylpentanoic acid, (L)-; 2-Amino-4-methylvaleric acid, (L)-; iso-C4H9CH(NH2)COOH; L-(-)-2-Amino-4-methylpentanoic acid; Norvaline, 4-methyl-, (L)-; Valeric acid, 2-amino-4-methyl-, (S)-; Leucin; (S)-2-Amino-4-methylpentanoic acid; (S)-Leucine; (S)-2-Amino-4-methylvaleric acid; L-Norvaline, 4-methyl-; NSC 46709
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Condensed phase thermochemistry data
  • Phase change data
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • IR Spectrum
  • References
  • Notes
• Other data available:
  • Mass spectrum (electron ionization)
• Data at other public NIST sites:
  • X-ray Photoelectron Spectroscopy Database, version 5.0
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Gas 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: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

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 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 solid

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:
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Enthalpy of sublimation

Enthalpy of phase transition

Entropy of phase transition

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 by: John E. Bartmess

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

C₆H₁₂NO₂^- +  =

By formula: C₆H₁₂NO₂^- + H⁺ = C₆H₁₃NO₂

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:
HL - Edward P. Hunter and 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

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

C₆H₁₂NO₂^- +  =

By formula: C₆H₁₂NO₂^- + H⁺ = C₆H₁₃NO₂

IR Spectrum

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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: Coblentz Society, Inc.

Condensed Phase Spectrum

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Notice: Except where noted, spectra from this collection were measured on dispersive instruments, often in carefully selected solvents, and hence may differ in detail from measurements on FTIR instruments or in other chemical environments. More information on the manner in which spectra in this collection were collected can be found here.

Notice: Concentration information is not available for this spectrum and, therefore, molar absorptivity values cannot be derived.

Additional Data

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, Notes

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

Wu, Zhu, et al., 1993
Wu, D.; Zhu, Y.; Gao, Z.; Qu, S., Determination of combustion heat of some amino acids, Wuhan Daxue Xuebao Ziran Kexueban, 1993, 78-82. [all data]

Hutchens, Cole, et al., 1963
Hutchens, J.O.; Cole, A.G.; Stout, J.W., Heat capacities from 11 to 305°K., entropies, and free energies of formation of L-valine, L-isoleucine, and L-leucine, J. Phys. Chem., 1963, 67, 1128-1130. [all data]

Huffman, Fox, et al., 1937
Huffman, H.M.; Fox, S.W.; Ellis, E.L., Thermal data. VII. The heats of combustion of seven amino acids, J. Am. Chem. Soc., 1937, 59, 2144-21. [all data]

Pedley, Naylor, et al., 1986
Pedley, J.B.; Naylor, R.D.; Kirby, S.P., Thermochemical Data of Organic Compounds, Chapman and Hall, New York, 1986, 1-792. [all data]

Tsuzuki and Hunt, 1957
Tsuzuki, T.; Hunt, H., Heats of combustion. VI. The heats of combustion of some amino acids, J. Phys. Chem., 1957, 61, 1668. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Fischer and Wrede, 1904
Fischer, E.; Wrede, F., Uber die Verbrennungswarme einiger organischer Verbindungen, Sitzungsber. Dtsch. Akad. Wiss. Berlin Kl. Math. Phys. Tech., 1904, 687-715. [all data]

Lemoult, 1904
Lemoult, M.P., Remarques sur une serie recenie de determinations calorimetriques, Compt. Rend., 1904, 663-635. [all data]

Badelin, Kulikov, et al., 1990
Badelin, V.G.; Kulikov, O.V.; Batagin, V.S.; Udzig, E.; Zielenkiewicz, A.; Zielenkiewicz, W.; Krestov, G.A., Physico-chemical properties of peptides and their solutions, Thermochim. Acta, 1990, 169, 81-93. [all data]

Kulikov, Kozlov, et al., 1989
Kulikov, O.V.; Kozlov, V.A.; Malenkina, L.I.; Badelin, V.G., Heat capacities of amino acids and peptides and excess characteristics ot their aqueous solutions, Sbornik Nauch. Trud., Termodin. Rast. neelect., Ivanovo, Inst. nevod. rast., 1989, Akad. [all data]

Spink and Wads, 1975
Spink, C.H.; Wads, I., Thermochemistry of solutions of biochemical model compounds. 4. The partial molar heat capacities of some amino acids in aqueous solution, J. Chem. Thermodynam., 1975, 7, 561-572. [all data]

Lähde, Raula, et al., 2009
Lähde, Anna; Raula, Janne; Malm, Jari; Kauppinen, Esko I.; Karppinen, Maarit, Sublimation and vapour pressure estimation of l-leucine using thermogravimetric analysis, Thermochimica Acta, 2009, 482, 1-2, 17-20, https://doi.org/10.1016/j.tca.2008.10.009 . [all data]

Svec and Clyde, 1965
Svec, H.J.; Clyde, D.D., Vapor pressures of some α-amino acids, J. Chem. Eng. Data, 1965, 10, 151. [all data]

Svec and Clyde, 1965, 2
Svec, H.J.; Clyde, D.D., Vapor Pressures of Some α-Amino Acids., J. Chem. Eng. Data, 1965, 10, 2, 151-152, https://doi.org/10.1021/je60025a024 . [all data]

Cox and Pilcher, 1970, 2
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press Inc., London, 1970, 643. [all data]

Clyde and Svec, 1964
Clyde, D.D.; Svec, H., , U. S. Atomic Energy Comm. IS-790, 1964, 1. [all data]

Grunenberg, Bougeard, et al., 1984
Grunenberg, A.; Bougeard, D.; Schrader, B., DSC-investigations of 22 crystalline neutral aliphatic amino acids in the temperature range 233 to 423 K, Thermochim. Acta, 1984, 77, 59-66. [all data]

Jones, Bernier, et al., 2007
Jones, C.M.; Bernier, M.; Carson, E.; Colyer, K.E.; Metz, R.; Pawlow, A.; Wischow, E.D.; Webb, I.; Andriole, E.J.; Poutsma, J.C., Gas-phase Acities of the 20 Protein Amino Acids, Int. J. Mass Spectrom., 2007, 267, 1-3, 54-62, https://doi.org/10.1016/j.ijms.2007.02.018 . [all data]

O'Hair, Bowie, et al., 1992
O'Hair, R.J.; Bowie, J.H.; Gronert, S., Gas Phase Acidity of the alpha-Amino Acids, Int. J. Mass Spectrom. Ion Proc., 1992, 117, 23, https://doi.org/10.1016/0168-1176(92)80083-D . [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Klasinc, 1976
Klasinc, L., Application of photoelectron spectroscopy to biologically active molecules and their constituent parts, J. Electron Spectrosc. Relat. Phenom., 1976, 8, 161. [all data]

Junk and Svec, 1963
Junk, G.; Svec, H., The mass spectra of the α-amino acids, J. Am. Chem. Soc., 1963, 85, 839. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, References

• Symbols used in this document:
  

  AE	Appearance energy
  Cp,solid	Constant pressure heat capacity of solid
  S°solid,1 bar	Entropy of solid at standard conditions (1 bar)
  ΔHtrs	Enthalpy of phase transition
  ΔStrs	Entropy of phase transition
  ΔcH°gas	Enthalpy of combustion of gas at standard conditions
  ΔcH°solid	Enthalpy of combustion of solid at standard conditions
  ΔfH°liquid	Enthalpy of formation of liquid at standard conditions
  ΔfH°solid	Enthalpy of formation of solid at standard conditions
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔsubH	Enthalpy of sublimation

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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