Hydroperoxy radical

• Formula: HO₂
• Molecular weight: 33.0067
• IUPAC Standard InChI: InChI=1S/HO2/c1-2/h1H Copy

  
• IUPAC Standard InChIKey: OUUQCZGPVNCOIJ-UHFFFAOYSA-N Copy
• CAS Registry Number: 3170-83-0
• 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.
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Reaction thermochemistry data
  • Henry's Law data
  • Gas phase ion energetics data
  • Vibrational and/or electronic energy levels
  • References
  • Notes
• Data at other public NIST sites:
  • Microwave spectra (on physics lab web site)
  • Electron-Impact Ionization Cross Sections (on physics web site)
  • Gas Phase Kinetics Database
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• NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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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.

Gas Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
    C_p = heat capacity (J/mol*K)
    H° = standard enthalpy (kJ/mol)
    S° = standard entropy (J/mol*K)
    t = temperature (K) / 1000.

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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 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

 +  =

By formula: O₂^- + H⁺ = HO₂

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:
HL - Edward P. Hunter and Sharon G. Lias
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

View reactions leading to HO₂⁺ (ion structure unspecified)

Electron affinity determinations

Ionization energy determinations

De-protonation reactions

 +  =

By formula: O₂^- + H⁺ = HO₂

Vibrational and/or electronic energy levels

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Henry's Law 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: Marilyn E. Jacox

State:   B

State:   A

State:   X

Additional references: Jacox, 1994, page 49; Jacox, 1998, page 153; Jacox, 2003, page 43; Radford, Evenson, et al., 1974; Hougen, 1975; Hougen, Radford, et al., 1975; Beers and Howard, 1975; Beers and Howard, 1976; Saito, 1977; Tuckett, Freedman, et al., 1979, 2; McKellar, 1979; Barnes, Brown, et al., 1980; Charo and De Lucia, 1982; Saito, Endo, et al., 1983; Lubic, Amano, et al., 1984; Uehara, Kawaguchi, et al., 1985; Sears, Takacs, et al., 1986; Chance, Park, et al., 1995; Chance, Ramsay, et al., 2001; Fink and Ramsay, 2002; DeSain, Ho, et al., 2003; Wang and Andrews, 2005; Fink and Ramsay, 2006

Notes

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, Notes

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

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Travers, Cowles, et al., 1989
Travers, M.J.; Cowles, D.C.; Ellison, G.B., Reinvestigation of the Electron Affinities of O2 and NO, Chem. Phys. Lett., 1989, 164, 5, 449, https://doi.org/10.1016/0009-2614(89)85237-6 . [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]

Ramond, Blanksby, et al., 2002
Ramond, T.M.; Blanksby, S.J.; Kato, S.; Bierbaum, V.M.; Davico, G.E.; Schwartz, R.L.; Lineberger, W.C.; Elliso, Heat of formation of the hydroperoxyl radical HOO via negative ion studies, J. Phys. Chem. A, 2002, 106, 42, 9641-9647, https://doi.org/10.1021/jp014614h . [all data]

Clifford, Wenthold, et al., 1998
Clifford, E.P.; Wenthold, P.G.; Gareyev, R.; Lineberger, W.C.; DePuy, C.H.; Bierbaum, V.M.; Ellison, G.B., Photoelectron spectroscopy, gas phase acidity, and thermochemistry of tert-butyl hydroperoxide: Mechanisms for the rearrangement of peroxyl radicals, J. Chem. Phys., 1998, 109, 23, 10293-10310, https://doi.org/10.1063/1.477725 . [all data]

Oakes, Harding, et al., 1985
Oakes, J.M.; Harding, L.B.; Ellison, G.B., The photoelectron spectroscopy of HO₂^-, J. Chem. Phys., 1985, 83, 5400. [all data]

Bierbaum, Schmidt, et al., 1981
Bierbaum, V.M.; Schmidt, R.J.; DePuy, C.H.; Mead, R.H.; Schulz, P.A.; Lineberger, W.C., Reactions of carbanions with triplet and singlet molecular oxygen, J. Am. Chem. Soc., 1981, 103, 6262. [all data]

Benson and Nangia, 1980
Benson, S.W.; Nangia, P.S., Electron affinity of HO₂. and HO_x radicals, J. Am. Chem. Soc., 1980, 102, 2843. [all data]

Dyke, Jonathan, et al., 1981
Dyke, J.M.; Jonathan, N.B.H.; Morris, A.; Winter, M., Vacuum ultraviolet photoelectron spectroscopy of transient species. Part 13. Observation of the X3A state of HO₂, Mol. Phys., 1981, 44, 1059. [all data]

Tal'roze, Butkovskaya, et al., 1978
Tal'roze, V.L.; Butkovskaya, N.I.; Larichev, M.N.; Leipunskii, I.O.; Morozov, I.I.; Dodonov, A.F.; Kudrov, B.V.; Zelenov, V.V.; Raznikov, V.V., Advances in the mass spectrometry of free radicals, Adv. Mass Spectrom., 1978, 7, 693. [all data]

Foner and Hudson, 1955
Foner, S.N.; Hudson, R.L., Ionization potential of the free HO₂ radical and the H-O₂ bond dissociation energy, J. Chem. Phys., 1955, 23, 1364. [all data]

Troe, 1969
Troe, J., Ber. Bunsenges. Phys. Chem., 1969, 73, 946. [all data]

Kijewski and Troe, 1971
Kijewski, H.; Troe, J., Study of the pyrolysis of H2O2 in the presence of H2and CO by use of UV absorption of HO2, Int. J. Chem. Kinet., 1971, 3, 3, 223, https://doi.org/10.1002/kin.550030304 . [all data]

Paukert and Johnston, 1972
Paukert, T.T.; Johnston, H.S., Spectra and Kinetics of the Hydroperoxyl Free Radical in the Gas Phase, J. Chem. Phys., 1972, 56, 6, 2824, https://doi.org/10.1063/1.1677613 . [all data]

Hochanadel, Ghormley, et al., 1972
Hochanadel, C.J.; Ghormley, J.A.; Ogren, P.J., Absorption Spectrum and Reaction Kinetics of the HO2 Radical in the Gas Phase, J. Chem. Phys., 1972, 56, 9, 4426, https://doi.org/10.1063/1.1677885 . [all data]

Crowley, Simon, et al., 1991
Crowley, J.N.; Simon, F.G.; Burrows, J.P.; Moortgat, G.K.; Jenkin, M.E.; Cox, R.A., The HO2 radical UV absorption spectrum measured by molecular modulation, UV/diode-array spectroscopy, J. Photochem. Photobiol. A: Chem., 1991, 60, 1, 1, https://doi.org/10.1016/1010-6030(91)90001-A . [all data]

Hunziker and Wendt, 1974
Hunziker, H.E.; Wendt, H.R., Near infrared absorption spectrum of HO2, J. Chem. Phys., 1974, 60, 11, 4622, https://doi.org/10.1063/1.1680949 . [all data]

Becker, Fink, et al., 1974
Becker, K.H.; Fink, E.H.; Langen, P.; Schurath, U., Near infrared emission bands of the HO2 radical, J. Chem. Phys., 1974, 60, 11, 4623, https://doi.org/10.1063/1.1680950 . [all data]

Hunziker and Wendt, 1976
Hunziker, H.E.; Wendt, H.R., Electronic absorption spectra of organic peroxyl radicals in the near infrared, J. Chem. Phys., 1976, 64, 8, 3488, https://doi.org/10.1063/1.432606 . [all data]

Freedman and Jones, 1976
Freedman, P.A.; Jones, W.J., J. Chem. Soc., 1976, Faraday Trans. 2 72, 207. [all data]

Becker, Fink, et al., 1978
Becker, K.H.; Fink, E.H.; Leiss, A.; Schurath, U., A study of the near infrared emission bands of the hydroperoxyl radical at medium resolution, Chem. Phys. Lett., 1978, 54, 1, 191, https://doi.org/10.1016/0009-2614(78)85694-2 . [all data]

Tuckett, Freedman, et al., 1979
Tuckett, R.P.; Freedman, P.A.; Jones, W.J., The emission bands of HO, Mol. Phys., 1979, 37, 2, 379, https://doi.org/10.1080/00268977900100331 . [all data]

Fink, Kruse, et al.
Fink, E.H.; Kruse, H.; Ramsay, D.A., Paper WF2, 42nd Symposium on Molecular Spectroscopy, Columbus, Ohio, June 1987.. [all data]

Fink and Ramsay, 1997
Fink, E.H.; Ramsay, D.A., High-Resolution Study of theÃ2A´ → X2A´´ Transition of HO2: Analysis of the 000--000 Band, J. Mol. Spectrosc., 1997, 185, 2, 304, https://doi.org/10.1006/jmsp.1997.7401 . [all data]

Ramond, Blanksby, et al., 2002, 2
Ramond, R.M.; Blanksby, S.J.; Kato, S.; Bierbaum, V.M.; Davico, G.E.; Schwartz, R.L.; Lineberger, W.C.; Ellison, G.B., Heat of Formation of the Hydroperoxyl Radical HOO Via Negative Ion Studies, J. Phys. Chem. A, 2002, 106, 42, 9641, https://doi.org/10.1021/jp014614h . [all data]

Holstein, Fink, et al., 1983
Holstein, K.J.; Fink, E.H.; Zabel, F., The ν3 vibration of electronically excited HO2(A2A´), J. Mol. Spectrosc., 1983, 99, 1, 231, https://doi.org/10.1016/0022-2852(83)90307-7 . [all data]

Yamada, Endo, et al., 1983
Yamada, C.; Endo, Y.; Hirota, E., Difference frequency laser spectroscopy of the ν1 band of the HO2 radical, J. Chem. Phys., 1983, 78, 7, 4379, https://doi.org/10.1063/1.445321 . [all data]

Thompson and Jacox, 1989
Thompson, W.E.; Jacox, M.E., The vibrational spectra of molecular ions isolated in solid neon. II. O+4 and O-4, J. Chem. Phys., 1989, 91, 7, 3826, https://doi.org/10.1063/1.456868 . [all data]

Jacox and Thompson
Jacox, M.E.; Thompson, W.E., J. Phys. Chem. A 117. [all data]

Milligan and Jacox, 1963
Milligan, D.E.; Jacox, M.E., Infrared Spectroscopic Evidence for the Species HO2, J. Chem. Phys., 1963, 38, 11, 2627, https://doi.org/10.1063/1.1733562 . [all data]

Jacox and Milligan, 1972
Jacox, M.E.; Milligan, D.E., Spectrum and structure of the HO2 free radical, J. Mol. Spectrosc., 1972, 42, 3, 495, https://doi.org/10.1016/0022-2852(72)90225-1 . [all data]

Smith and Andrews, 1974
Smith, D.W.; Andrews, L., Argon matrix infrared spectra and vibrational analysis of the hydroperoxyl and deuteroperoxyl free radicals, J. Chem. Phys., 1974, 60, 1, 81, https://doi.org/10.1063/1.1680809 . [all data]

Bandow and Akimoto, 1985
Bandow, H.; Akimoto, H., Photochemistry of ketene in oxygen/argon matrixes and in solid oxygen at 11 K, J. Phys. Chem., 1985, 89, 5, 845, https://doi.org/10.1021/j100251a026 . [all data]

Nagai, Endo, et al., 1981
Nagai, K.; Endo, Y.; Hirota, E., Diode laser spectroscopy of the HO2 ν2 band, J. Mol. Spectrosc., 1981, 89, 2, 520, https://doi.org/10.1016/0022-2852(81)90044-8 . [all data]

Burkholder, Hammer, et al., 1992
Burkholder, J.B.; Hammer, P.D.; Howard, C.J.; Towle, J.P.; Brown, J.M., Fourier transform spectroscopy of the ν2 and ν3 bands of HO2, J. Mol. Spectrosc., 1992, 151, 2, 493, https://doi.org/10.1016/0022-2852(92)90582-9 . [all data]

Johns, McKellar, et al., 1978
Johns, J.W.C.; McKellar, A.R.W.; Riggin, M., Laser magnetic resonance spectroscopy of the ν3 fundamental band of HO2 at 9.1 μm, J. Chem. Phys., 1978, 68, 9, 3957, https://doi.org/10.1063/1.436308 . [all data]

Buchanan, Thrush, et al., 1983
Buchanan, J.W.; Thrush, B.A.; Tyndall, G.S., The absolute intensity of the ν3 band of HO2, Chem. Phys. Lett., 1983, 103, 2, 167, https://doi.org/10.1016/0009-2614(83)87487-9 . [all data]

Zahniser and Stanton, 1984
Zahniser, M.S.; Stanton, A.C., A measurement of the vibrational band strength for the ν3 band of the HO2 radical, J. Chem. Phys., 1984, 80, 10, 4951, https://doi.org/10.1063/1.446517 . [all data]

Nelson and Zahniser, 1991
Nelson, D.D., Jr.; Zahniser, M.S., Diode laser spectroscopy of the ν3 vibration of the HO2 radical, J. Mol. Spectrosc., 1991, 150, 2, 527, https://doi.org/10.1016/0022-2852(91)90247-8 . [all data]

Jacox, 1994
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules, American Chemical Society, Washington, DC, 1994, 464. [all data]

Jacox, 1998
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement A, J. Phys. Chem. Ref. Data, 1998, 27, 2, 115-393, https://doi.org/10.1063/1.556017 . [all data]

Jacox, 2003
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement B, J. Phys. Chem. Ref. Data, 2003, 32, 1, 1-441, https://doi.org/10.1063/1.1497629 . [all data]

Radford, Evenson, et al., 1974
Radford, H.E.; Evenson, K.M.; Howard, C.J., HO2 detected by laser magnetic resonance, J. Chem. Phys., 1974, 60, 8, 3178, https://doi.org/10.1063/1.1681503 . [all data]

Hougen, 1975
Hougen, J.T., The assignment of molecular infrared spectra from a laser magnetic resonance spectrometer, J. Mol. Spectrosc., 1975, 54, 3, 447, https://doi.org/10.1016/0022-2852(75)90172-1 . [all data]

Hougen, Radford, et al., 1975
Hougen, J.T.; Radford, H.E.; Evenson, K.M.; Howard, C.J., Analysis of the laser magnetic resonance spectrum of HO2, J. Mol. Spectrosc., 1975, 56, 2, 210, https://doi.org/10.1016/0022-2852(75)90236-2 . [all data]

Beers and Howard, 1975
Beers, Y.; Howard, C.J., The microwave spectrum of HO2 near 65 GHz, J. Chem. Phys., 1975, 63, 10, 4212, https://doi.org/10.1063/1.431191 . [all data]

Beers and Howard, 1976
Beers, Y.; Howard, C.J., The spectrum of DO2 near 60 GHz and the structure of the hydroperoxyl radical, J. Chem. Phys., 1976, 64, 4, 1541, https://doi.org/10.1063/1.432375 . [all data]

Saito, 1977
Saito, S., Microwave spectrum of the HO2 radical, J. Mol. Spectrosc., 1977, 65, 2, 229, https://doi.org/10.1016/0022-2852(77)90190-4 . [all data]

Tuckett, Freedman, et al., 1979, 2
Tuckett, R.P.; Freedman, P.A.; Jones, W.J., The near infra-red emission band of DO, Mol. Phys., 1979, 37, 2, 403, https://doi.org/10.1080/00268977900100341 . [all data]

McKellar, 1979
McKellar, A.R.W., Laser magnetic resonance spectroscopy of the ν2 fundamental band of DO2 at 9.8 μm, J. Chem. Phys., 1979, 71, 1, 81, https://doi.org/10.1063/1.438060 . [all data]

Barnes, Brown, et al., 1980
Barnes, C.E.; Brown, J.M.; Radford, H.E., The EPR and LMR spectra of the DO2 radical: Determination of ground-state parameters, J. Mol. Spectrosc., 1980, 84, 1, 179, https://doi.org/10.1016/0022-2852(80)90252-0 . [all data]

Charo and De Lucia, 1982
Charo, A.; De Lucia, F.C., The millimeter and submillimeter spectrum of HO2: The effects of unpaired electronic spin in a light asymmetric rotor, J. Mol. Spectrosc., 1982, 94, 2, 426, https://doi.org/10.1016/0022-2852(82)90018-2 . [all data]

Saito, Endo, et al., 1983
Saito, S.; Endo, Y.; Hirota, E., The microwave spectrum of the DO2 radical, J. Mol. Spectrosc., 1983, 98, 1, 183, https://doi.org/10.1016/0022-2852(83)90208-4 . [all data]

Lubic, Amano, et al., 1984
Lubic, K.G.; Amano, T.; Uehara, H.; Kawaguchi, K.; Hirota, E., The ν1 band of the DO2 radical by difference frequency laser and diode laser spectroscopy: The equilibrium structure of the hydroperoxyl radical, J. Chem. Phys., 1984, 81, 11, 4826, https://doi.org/10.1063/1.447508 . [all data]

Uehara, Kawaguchi, et al., 1985
Uehara, H.; Kawaguchi, K.; Hirota, E., Diode laser spectroscopy of the ν3 and ν2 fundamental bands of DO2, J. Chem. Phys., 1985, 83, 11, 5479, https://doi.org/10.1063/1.449668 . [all data]

Sears, Takacs, et al., 1986
Sears, T.J.; Takacs, G.A.; Howard, C.J.; Crownover, R.L.; Helminger, P.; De Lucia, F.C., Rotational spectroscopy of DO2 by FIR LMR and millimeter-wave absorption, J. Mol. Spectrosc., 1986, 118, 1, 103, https://doi.org/10.1016/0022-2852(86)90228-6 . [all data]

Chance, Park, et al., 1995
Chance, K.V.; Park, K.; Evenson, K.M.; Zink, L.R.; Stroh, F., Far-Infrared Spectrum of HO2, J. Mol. Spectrosc., 1995, 172, 2, 407, https://doi.org/10.1006/jmsp.1995.1188 . [all data]

Chance, Ramsay, et al., 2001
Chance, K.V.; Ramsay, D.A.; Fink, E.H., Improved Molecular Constants for the Ground State of DO2, J. Mol. Spectrosc., 2001, 207, 1, 123, https://doi.org/10.1006/jmsp.2001.8310 . [all data]

Fink and Ramsay, 2002
Fink, E.H.; Ramsay, D.A., High-Resolution Study of the Atilde;2A´→X2A´´ Transition of DO2: Analysis of the 000--000 Band, J. Mol. Spectrosc., 2002, 216, 2, 322, https://doi.org/10.1006/jmsp.2002.8621 . [all data]

DeSain, Ho, et al., 2003
DeSain, J.D.; Ho, A.D.; Taatjes, C.A., High-resolution diode laser absorption spectroscopy of the O--H stretch overtone band (2,0,0)←(0,0,0) of the HO2 radical, J. Mol. Spectrosc., 2003, 219, 1, 163, https://doi.org/10.1016/S0022-2852(03)00022-5 . [all data]

Wang and Andrews, 2005
Wang, X.; Andrews, L., Infrared Spectrum of Hg(OH), Inorg. Chem., 2005, 44, 1, 108, https://doi.org/10.1021/ic048673w . [all data]

Fink and Ramsay, 2006
Fink, E.H.; Ramsay, D.A., Analysis of perturbations in the state of HO2, J. Mol. Struct., 2006, 795, 1-3, 155, https://doi.org/10.1016/j.molstruc.2005.11.045 . [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Henry's Law data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References

• Symbols used in this document:
  

  EA	Electron affinity
  IE (evaluated)	Recommended ionization energy
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  d(ln(kH))/d(1/T)	Temperature dependence parameter for Henry's Law constant
  k°H	Henry's Law constant at 298.15K
  ΔfH°gas	Enthalpy of formation of gas at standard conditions
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions

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