Pyridazine

• Formula: C₄H₄N₂
• Molecular weight: 80.0880
• IUPAC Standard InChI: InChI=1S/C4H4N2/c1-2-4-6-5-3-1/h1-4H Copy

  
• IUPAC Standard InChIKey: PBMFSQRYOILNGV-UHFFFAOYSA-N Copy
• CAS Registry Number: 289-80-5
• 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: Orthodiazine; 1,2-Diazabenzene; 1,2-Diazine
• 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
  • Gas phase ion energetics data
  • Mass spectrum (electron ionization)
  • UV/Visible spectrum
  • References
  • Notes
• Other data available:
  • Condensed phase thermochemistry data
  • Phase change data
  • IR Spectrum
  • Gas Chromatography
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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

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

C₄H₃N₂^- +  =

By formula: C₄H₃N₂^- + H⁺ = C₄H₄N₂

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 C₄H₄N₂⁺ (ion structure unspecified)

Electron affinity determinations

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

C₄H₃N₂^- +  =

By formula: C₄H₃N₂^- + H⁺ = C₄H₄N₂

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

UV/Visible 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: Victor Talrose, Alexander N. Yermakov, Alexy A. Usov, Antonina A. Goncharova, Axlexander N. Leskin, Natalia A. Messineva, Natalia V. Trusova, Margarita V. Efimkina

Spectrum

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Additional Data

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Mass spectrum (electron ionization), UV/Visible spectrum, Notes

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

Tjebbes, 1962
Tjebbes, J., The heats of combustion and formation of the three diazines and their resonance energies, Acta Chem. Scand., 1962, 16, 916-921. [all data]

Meot-ner and Kafafi, 1988
Meot-ner, M.; Kafafi, S.A., Carbon Acidities of Aromatic Compounds, J. Am. Chem. Soc., 1988, 110, 19, 6297, https://doi.org/10.1021/ja00227a003 . [all data]

Wren, Vogelhuber, et al., 2012
Wren, S.W.; Vogelhuber, K.M.; Garver, J.M.; Kato, S.; Sheps, L.; Bierbaum, V.M.; Lineberger, W.C., C-H Bond Strengths and Acidities in Aromatic Systems: Effects of Nitrogen Incorporation in Mono-, Di-, and Triazines, J. Am. Chem. Soc., 2012, 134, 15, 6584-6595, https://doi.org/10.1021/ja209566q . [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]

Suess, Liu, et al., 2003
Suess, L.; Liu, Y.; Parthasarathy, R.; Dunning, F.B., Dipole-bound negative ions: Collisional destruction and blackbody-radiation-induced photodetachment, J. Chem. Phys., 2003, 119, 24, 12890-12894, https://doi.org/10.1063/1.1628215 . [all data]

Nenner and Schultz, 1975
Nenner, I.; Schultz, G.J., Temporary negative ions and electron affinities of benzene and N-heterocyclic molecules: Pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine, J. Chem. Phys., 1975, 62, 1747. [all data]

Gleiter, Heilbronner, et al., 1972
Gleiter, R.; Heilbronner, E.; Hornung, V., Photoelectron spectra of azabenzenes azanaphthalenes: I. Pyridine, diazines s-triazine and s-tetrazine, Helv. Chim. Acta, 1972, 55, 255. [all data]

Asbrink, Fridh, et al., 1972
Asbrink, L.; Fridh, C.; Jonsson, B.O.; Lindholm, E., Rydberg series in small molecules. XVII. Photoelectron, UV, mass and electron impact spectra of pyridazine, Int. J. Mass Spectrom. Ion Phys., 1972, 8, 229. [all data]

Dewar and Worley, 1969
Dewar, M.J.S.; Worley, S.D., Photoelectron spectra of molecules. II.The ionization potentials of azabenzenes and azanaphthalenes, J. Chem. Phys., 1969, 51, 263. [all data]

Yencha and El-Sayed, 1968
Yencha, A.J.; El-Sayed, M.A., Lowest ionization potentials of some nitrogen heterocyclics, J. Chem. Phys., 1968, 48, 3469. [all data]

Suffolk, 1974
Suffolk, R.J., The photoelectron spectra of the perfluorodiazines, J. Electron Spectrosc. Relat. Phenom., 1974, 3, 53. [all data]

Gleiter, Heilbronner, et al., 1970
Gleiter, R.; Heilbronner, E.; Hornung, V., Lone pair interaction in pyridazine, pyrimidine, and pyrazine, Angew. Chem. Int. Ed. Engl., 1970, 9, 901. [all data]

Momigny, Urbain, et al., 1965
Momigny, J.; Urbain, J.; Wankenne, H., Les effets de l'impact electronique sur la pyridine et les diazines isomeres, Bull. Soc. Roy. Sci. Liege, 1965, 34, 337. [all data]

Halverson and Hirt, 1951
Halverson, F.; Hirt, R.C., J. Chem. Phys., 1951, 19, 711. [all data]

Notes

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• Symbols used in this document:
  

  AE	Appearance energy
  EA	Electron affinity
  IE (evaluated)	Recommended ionization energy
  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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