Pyridine

• Formula: C₅H₅N
• Molecular weight: 79.0999
• IUPAC Standard InChI: InChI=1S/C5H5N/c1-2-4-6-5-3-1/h1-5H Copy

  
• IUPAC Standard InChIKey: JUJWROOIHBZHMG-UHFFFAOYSA-N Copy
• CAS Registry Number: 110-86-1
• 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.
• Isotopologues:
  • Pyridine-D5-
• Other names: Azabenzene; Azine; NCI-C55301; Piridina; Pirydyna; Pyridin; Rcra waste number U196; UN 1282; Pyr; CP 32; NSC 406123
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Phase change data
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
  • Condensed phase thermochemistry data
  • Henry's Law data
  • Ion clustering data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • UV/Visible spectrum
  • Gas Chromatography
• Data at other public NIST sites:
  • Gas Phase Kinetics Database
  • X-ray Photoelectron Spectroscopy Database, version 5.0
• Options:
  • Switch to SI units

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• NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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Phase change data

Go To: Top, Reaction thermochemistry 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 as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
BS - Robert L. Brown and Stephen E. Stein
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.
DH - Eugene S. Domalski and Elizabeth D. Hearing

Enthalpy of vaporization

Enthalpy of vaporization

Δ_vapH = A exp(-βT_r) (1 − T_r)^β
    Δ_vapH = Enthalpy of vaporization (at saturation pressure) (kcal/mol)
    T_r = reduced temperature (T / T_c)

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Antoine Equation Parameters

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

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Enthalpy of fusion

Entropy of fusion

Reaction thermochemistry data

Go To: Top, Phase change 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 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
RCD - Robert C. Dunbar

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

C₅H₄N^- +  =

By formula: C₅H₄N^- + H⁺ = C₅H₅N

C₅H₆N⁺ +  = (C₅H₆N⁺ • )

By formula: C₅H₆N⁺ + C₅H₅N = (C₅H₆N⁺ • C₅H₅N)

 + 3 =

By formula: C₅H₅N + 3H₂ = C₅H₁₁N

 +  = ( • )

By formula: Cl^- + C₅H₅N = (Cl^- • C₅H₅N)

(C₅H₆N⁺ • 2) +  = (C₅H₆N⁺ • 3)

By formula: (C₅H₆N⁺ • 2C₅H₅N) + C₅H₅N = (C₅H₆N⁺ • 3C₅H₅N)

 +  = ( • )

By formula: Li⁺ + C₅H₅N = (Li⁺ • C₅H₅N)

 +  = ( • )

By formula: K⁺ + C₅H₅N = (K⁺ • C₅H₅N)

( • 2) +  = ( • 3)

By formula: (Ag⁺ • 2C₅H₅N) + C₅H₅N = (Ag⁺ • 3C₅H₅N)

( • 3) +  = ( • 4)

By formula: (Ag⁺ • 3C₅H₅N) + C₅H₅N = (Ag⁺ • 4C₅H₅N)

( • ) +  = ( • 2)

By formula: (Cl^- • C₅H₅N) + C₅H₅N = (Cl^- • 2C₅H₅N)

(C₅H₆N⁺ • ) +  = (C₅H₆N⁺ • 2)

By formula: (C₅H₆N⁺ • C₅H₅N) + C₅H₅N = (C₅H₆N⁺ • 2C₅H₅N)

H₂O₃^- +  +  = C₅H₇NO₃^-

By formula: H₂O₃^- + C₅H₅N + H₂O = C₅H₇NO₃^-

 +  = C₅H₅NO₂^-

By formula: O₂^- + C₅H₅N = C₅H₅NO₂^-

 +  = C₅H₅N₂O^-

By formula: NO^- + C₅H₅N = C₅H₅N₂O^-

3 +  = 3 + KClO₃

By formula: 3C₅H₅NO + ClK = 3C₅H₅N + KClO₃

3 +  = 3 + KBrO₃

By formula: 3C₅H₅NO + BrK = 3C₅H₅N + KBrO₃

 +  = ( • )

By formula: Fe⁺ + C₅H₅N = (Fe⁺ • C₅H₅N)

 +  = ( • )

By formula: Cr⁺ + C₅H₅N = (Cr⁺ • C₅H₅N)

 +  = ( • )

By formula: Ti⁺ + C₅H₅N = (Ti⁺ • C₅H₅N)

 +  = ( • )

By formula: Mn⁺ + C₅H₅N = (Mn⁺ • C₅H₅N)

 +  = ( • )

By formula: Sc⁺ + C₅H₅N = (Sc⁺ • C₅H₅N)

 +  = ( • )

By formula: Mg⁺ + C₅H₅N = (Mg⁺ • C₅H₅N)

 +  = ( • )

By formula: V⁺ + C₅H₅N = (V⁺ • C₅H₅N)

 +  = ( • )

By formula: Ni⁺ + C₅H₅N = (Ni⁺ • C₅H₅N)

 +  = ( • )

By formula: Al⁺ + C₅H₅N = (Al⁺ • C₅H₅N)

 +  = ( • )

By formula: Zn⁺ + C₅H₅N = (Zn⁺ • C₅H₅N)

 +  = ( • )

By formula: Co⁺ + C₅H₅N = (Co⁺ • C₅H₅N)

 +  = ( • )

By formula: Cu⁺ + C₅H₅N = (Cu⁺ • C₅H₅N)

 +  = ( • )

By formula: Na⁺ + C₅H₅N = (Na⁺ • C₅H₅N)

Gas phase ion energetics data

Go To: Top, Phase change data, Reaction thermochemistry data, References, Notes

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
MM - Michael M. Meot-Ner (Mautner)
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

Proton affinity at 298K

Protonation entropy at 298K

Ionization energy determinations

Appearance energy determinations

De-protonation reactions

C₅H₄N^- +  =

By formula: C₅H₄N^- + H⁺ = C₅H₅N

References

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

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

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Heilbronner, Hornung, et al., 1972
Heilbronner, E.; Hornung, V.; Pinkerton, F.H.; Thames, S.F., 31. Photoelectron spectra of azabenzenes and azanaphthalenes: III. The orbital sequence in methyl- and trimethylsilyl- substituted pyridines, Helv. Chim. Acta, 1972, 55, 289. [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]

Lifshitz and Malinovich, 1984
Lifshitz, C.; Malinovich, Y., Time resolved photoionization mass spectrometry in the millisecond range, Int. J. Mass Spectrom. Ion Processes, 1984, 60, 99. [all data]

Burgers and Holmes, 1984
Burgers, P.C.; Holmes, J.L., Fragmentation rate constants and appearance energies for reactions having a large kinetic shift and the energy partitioning in their metastable decomposition, Int. J. Mass Spectrom. Ion Processes, 1984, 58, 15. [all data]

Rosenstock, Stockbauer, et al., 1981
Rosenstock, H.M.; Stockbauer, R.; Parr, A.C., Unimolecular kinetis of pyridine ion fragmentation, Int. J. Mass Spectrom. Ion Phys., 1981, 38, 323. [all data]

Rosenstock, McCulloh, et al., 1977
Rosenstock, H.M.; McCulloh, K.E.; Lossing, F.P., On the mechanisms of C₆H₆ ionization fragmentation, Int. J. Mass Spectrom. Ion Phys., 1977, 25, 327. [all data]

Beynon, Hopkinson, et al., 1969
Beynon, J.H.; Hopkinson, J.A.; Lester, G.R., Mass spectrometry-the appearance potentials of "meta-stable peaks" in some aromatic nitro compounds - a chemical reaction in the mass spectrometer, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 291. [all data]

Notes

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• Symbols used in this document:
  

  AE	Appearance energy
  IE (evaluated)	Recommended ionization energy
  Pc	Critical pressure
  Tboil	Boiling point
  Tc	Critical temperature
  Tfus	Fusion (melting) point
  Ttriple	Triple point temperature
  Vc	Critical volume
  ΔfusH	Enthalpy of fusion
  ΔfusS	Entropy of fusion
  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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