Isocyanic acid

• Formula: CHNO
• Molecular weight: 43.0247
• IUPAC Standard InChI: InChI=1S/CHNO/c2-1-3/h2H Copy

  
• IUPAC Standard InChIKey: OWIKHYCFFJSOEH-UHFFFAOYSA-N Copy
• CAS Registry Number: 75-13-8
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
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• Information on this page:
  • Gas phase thermochemistry data
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • Vibrational and/or electronic energy levels
  • References
  • Notes
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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 as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

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

CNO^- +  =

By formula: CNO^- + H⁺ = CHNO

(CAS Reg. No. 1140500-24-8 • 4294967295) +  = CAS Reg. No. 1140500-24-8

By formula: (CAS Reg. No. 1140500-24-8 • 4294967295CHNO) + CHNO = CAS Reg. No. 1140500-24-8

(CAS Reg. No. 67131-48-0 • 4294967295) +  = CAS Reg. No. 67131-48-0

By formula: (CAS Reg. No. 67131-48-0 • 4294967295CHNO) + CHNO = CAS Reg. No. 67131-48-0

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
LL - Sharon G. Lias and Joel F. Liebman
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

CNO^- +  =

By formula: CNO^- + H⁺ = CHNO

Vibrational and/or electronic energy levels

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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:
J - Marilyn E. Jacox
Shim - Takehiko Shimanouchi

State:   ?

State:   ?

State:   ?

State:   ?

State:   ?

State:   A

State:   X

Additional references: Jacox, 1994, page 163; Jacox, 1998, page 236; Jacox, 2003, page 190; Ashby and Werner, 1966; Yamada, 1980; Steiner, Polo, et al., 1981

Notes

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, NIST Free Links, 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]

Okabe, 1970
Okabe, H., Photodissociation of HNCO in the vacuum ultraviolet; production of NCO A₂Σ and NH (A₃π, πC¹), J. Chem. Phys., 1970, 53, 3507-3515. [all data]

Bradforth, Kim, et al., 1993
Bradforth, S.E.; Kim, E.H.; Arnold, D.W.; Neumark, D.M., Photoelectron Spectroscopy of CN-, NCO-, and NCS-, J. Chem. Phys., 1993, 98, 2, 800, https://doi.org/10.1063/1.464244 . [all data]

Wight and Beauchamp, 1980
Wight, C.A.; Beauchamp, J.L., Acidity, basicity, and ion/molecule reactions of isocyanic acid in the gas phase by ICR spectroscopy, J. Phys. Chem., 1980, 84, 2503. [all data]

Taft, 1987
Taft, R.W., The Nature and Analysis of Substitutent Electronic Effects, Personal communication. See also Prog. Phys. Org. Chem., 1987, 16, 1. [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]

Ruscic and Berkowitz, 1994
Ruscic, B.; Berkowitz, J., The H-NCO bond energy and Hf(NCO) from photoionization mass spectrometric studies of HNCO and NCO, J. Chem. Phys., 1994, 100, 4498. [all data]

Cradock, Ebsworth, et al., 1972
Cradock, S.; Ebsworth, E.A.V.; Murdoch, J.D., Photoelectron spectra of some Group 4 pseudohalides and related compounds, J. Chem. Soc. Faraday Trans. 2, 1972, 68, 86. [all data]

Rowland, Eland, et al., 1968
Rowland, C.G.; Eland, J.H.D.; Danby, C.J., A spin-forbidden predissociation in the mass spectrum of isocyanic acid, Chem. Commun., 1968, 1535. [all data]

Compernolle, 1975
Compernolle, F., Mass spectrum and heat of formation of isocyanic acid. Production of [HCO]⁺ from discrete electronic state of molecular ion, Org. Mass Spectrom., 1975, 10, 289. [all data]

Bogan and Hand, 1971
Bogan, D.J.; Hand, C.W., Mass spectrum of isocyanic acid, J. Phys. Chem., 1971, 75, 1532. [all data]

Okabe, 1970, 2
Okabe, H., J. Chem. Phys., 1970, 53, 3507. [all data]

Dixon and Kirby, 1968
Dixon, R.N.; Kirby, G.H., Ultra-violet absorption spectrum of isocyanic acid, Trans. Faraday Soc., 1968, 64, 2002, https://doi.org/10.1039/tf9686402002 . [all data]

Berghout, Crim, et al., 2000
Berghout, H.L.; Crim, F.F.; Zyrianov, M.; Reisler, H., The electronic origin and vibrational levels of the first excited singlet state of isocyanic acid (HNCO), J. Chem. Phys., 2000, 112, 15, 6678, https://doi.org/10.1063/1.481242 . [all data]

Herzberg and Reid, 1950
Herzberg, G.; Reid, C., Infra-red spectrum and structure of the HNCO molecule, Discuss. Faraday Soc., 1950, 9, 92, https://doi.org/10.1039/df9500900092 . [all data]

Reid, 1950
Reid, C., Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths V. The Spectrum of Isocyanic Acid, J. Chem. Phys., 1950, 18, 12, 1544, https://doi.org/10.1063/1.1747538 . [all data]

Teles, Maier, et al., 1989
Teles, J.H.; Maier, G.; Hess, B.A., Jr.; Schaad, L.J.; Winnewisser, M.; Winnewisser, B.P., The CHNO Isomers, Chem. Ber., 1989, 122, 4, 753, https://doi.org/10.1002/cber.19891220425 . [all data]

Yamada, Winnewisser, et al., 1990
Yamada, K.M.T.; Winnewisser, M.; Johns, J.W.C., High-resolution spectrum of the ν1 fundamental band of isocyanic acid, HNCO, J. Mol. Spectrosc., 1990, 140, 2, 353, https://doi.org/10.1016/0022-2852(90)90147-I . [all data]

Brown, Berghout, et al., 1997
Brown, S.S.; Berghout, H.L.; Crim, F.F., Raman spectroscopy of the ν1 N--H stretch fundamental in isocyanic acid (HNCO): State mixing probed by photoacoustic spectroscopy and by photodissociation of vibrationally excited states, J. Chem. Phys., 1997, 106, 14, 5805, https://doi.org/10.1063/1.473246 . [all data]

Pettersson, Khriachtchev, et al., 1999
Pettersson, M.; Khriachtchev, L.; Jolkkonen, S.; Rasanen, M., Photochemistry of HNCO in Solid Xe: Channels of UV Photolysis and Creation of H, J. Phys. Chem. A, 1999, 103, 45, 9154, https://doi.org/10.1021/jp992224d . [all data]

Lemoine, Yamada, et al., 1982
Lemoine, B.; Yamada, K.; Winnewisser, G., Diode Laser Spectrum of the Fundamental v2 Band of HNCO, Ber. Bunsenges. Phys. Chem., 1982, 86, 9, 795, https://doi.org/10.1002/bbpc.19820860906 . [all data]

Steiner, Polo, et al., 1983
Steiner, D.A.; Polo, S.R.; McCubbin, T.K.; Wishah, K.A., Infrared spectrum of the fundamental ν2 of isocyanic acid, J. Mol. Spectrosc., 1983, 98, 2, 453, https://doi.org/10.1016/0022-2852(83)90254-0 . [all data]

Brown, Berghout, et al., 1997, 2
Brown, S.S.; Berghout, H.L.; Crim, F.F., Raman spectroscopy of the N--C--O symmetric (ν[sub 3]) and antisymmetric (ν[sub 2]) stretch fundamentals in HNCO, J. Chem. Phys., 1997, 107, 23, 9764, https://doi.org/10.1063/1.475274 . [all data]

Crowley and Sodeau, 1989
Crowley, J.N.; Sodeau, J.R., Reaction between hydrocyanic acid and O(1D2) or O(3P) oxygen atoms in low-temperature matrixes, J. Phys. Chem., 1989, 93, 8, 3100, https://doi.org/10.1021/j100345a044 . [all data]

Steiner, Wishah, et al., 1979
Steiner, D.A.; Wishah, K.A.; Polo, S.R.; McCubbin, T.K., Infrared spectrum of isocyanic acid between 465 and 1100 cm-1, J. Mol. Spectrosc., 1979, 76, 1-3, 341, https://doi.org/10.1016/0022-2852(79)90233-9 . [all data]

Fusina, Carlotti, et al., 1984
Fusina, L.; Carlotti, M.; Carli, B., Infrared spectrum of HNCO between 8 and 80 cm, Can. J. Phys., 1984, 62, 12, 1452, https://doi.org/10.1139/p84-192 . [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]

Ashby and Werner, 1966
Ashby, R.A.; Werner, R.L., The infra-red absorption spectrum of DNCO, Spectrochim. Acta, 1966, 22, 7, 1345, https://doi.org/10.1016/0371-1951(66)80038-3 . [all data]

Yamada, 1980
Yamada, K., Molecular structure and centrifugal distortion constants of isocyanic acid from the microwave, millimeter wave, and far-infrared spectra, J. Mol. Spectrosc., 1980, 79, 2, 323, https://doi.org/10.1016/0022-2852(80)90217-9 . [all data]

Steiner, Polo, et al., 1981
Steiner, D.A.; Polo, S.R.; McCubbin, T.K.; Wishah, K.A., Infrared spectrum of the fundamental ν, Can. J. Phys., 1981, 59, 10, 1313, https://doi.org/10.1139/p81-172 . [all data]

Notes

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• Symbols used in this document:
  

  AE	Appearance energy
  IE (evaluated)	Recommended ionization energy
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  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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