Indole

Data at NIST subscription sites:

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.


Condensed phase thermochemistry data

Go To: Top, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, UV/Visible spectrum, 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: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity Value Units Method Reference Comment
Δfsolid20.71 ± 0.18kcal/molCcbGood, 1972 
Quantity Value Units Method Reference Comment
Δcsolid-1012.22 ± 0.15kcal/molCcbGood, 1972 
Δcsolid-1013.5kcal/molCcbZimmerman and Geisenfelder, 1961 
Δcsolid-1019.4 ± 1.0kcal/molCcbStern and Klebs, 1933Reanalyzed by Cox and Pilcher, 1970, Original value = -1021.1 kcal/mol; Heat of combustion at 288 K

Phase change data

Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, UV/Visible spectrum, 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:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity Value Units Method Reference Comment
Tboil527.2KN/AWeast and Grasselli, 1989BS
Tboil526.15KN/ACooper, Crowne, et al., 1967Uncertainty assigned by TRC = 0.6 K; TRC
Tboil526.65KN/ALecat, 1947Uncertainty assigned by TRC = 0.7 K; TRC
Tboil526.KN/AAdkins and Coonradt, 1941Uncertainty assigned by TRC = 4. K; TRC
Quantity Value Units Method Reference Comment
Tfus325. ± 1.KAVGN/AAverage of 10 values; Individual data points
Quantity Value Units Method Reference Comment
Δsub18.5 ± 0.26kcal/molMERibeiro da Silva, Cabral, et al., 2008Based on data from 275. to 291. K.; AC
Δsub22.7kcal/molVZimmerman and Geisenfelder, 1961ALS

Reduced pressure boiling point

Tboil (K) Pressure (atm) Reference Comment
396.70.007Weast and Grasselli, 1989BS

Enthalpy of sublimation

ΔsubH (kcal/mol) Temperature (K) Method Reference Comment
18.7 ± 0.33283.MERibeiro da Silva, Cabral, et al., 2008Based on data from 275. to 291. K.; AC
17.9305.AStephenson and Malanowski, 1987Based on data from 291. to 319. K.; AC
18.6 ± 0.38289.MEArshadi, 1974Based on data from 275. to 303. K.; AC
16.7292.N/AAihara, 1955Based on data from 283. to 301. K.; AC
17.9305.N/ASerpinskii, Voitkevich, et al., 1954Based on data from 283. to 328. K. See also Jones, 1960.; AC

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:


Reaction thermochemistry data

Go To: Top, Condensed phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, UV/Visible spectrum, 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

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

C8H6N- + Hydrogen cation = Indole

By formula: C8H6N- + H+ = C8H7N

Quantity Value Units Method Reference Comment
Δr351.9 ± 2.5kcal/molTDEqMeot-ner, Liebman, et al., 1988gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Δr349.2 ± 2.1kcal/molG+TSTaft and Bordwell, 1988gas phase; B
Quantity Value Units Method Reference Comment
Δr344.1 ± 2.0kcal/molTDEqMeot-ner, Liebman, et al., 1988gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Δr341.9 ± 2.0kcal/molIMRETaft and Bordwell, 1988gas phase; B

MeCO2 anion + Indole = (MeCO2 anion • Indole)

By formula: C2H3O2- + C8H7N = (C2H3O2- • C8H7N)

Quantity Value Units Method Reference Comment
Δr27.9 ± 1.0kcal/molTDAsMeot-ner, 1988gas phase; B,M
Quantity Value Units Method Reference Comment
Δr30.4cal/mol*KPHPMSMeot-ner, 1988gas phase; M
Quantity Value Units Method Reference Comment
Δr18.8 ± 1.0kcal/molTDAsMeot-ner, 1988gas phase; B

Gas phase ion energetics data

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Ion clustering data, IR Spectrum, UV/Visible spectrum, 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
LL - Sharon G. Lias and Joel F. Liebman
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

View reactions leading to C8H7N+ (ion structure unspecified)

Quantity Value Units Method Reference Comment
IE (evaluated)7.7602 ± 0.0006eVN/AN/AL
Quantity Value Units Method Reference Comment
Proton affinity (review)223.1kcal/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity215.6kcal/molN/AHunter and Lias, 1998HL

Electron affinity determinations

EA (eV) Reference Comment
0.00351 ± 0.00022Carles, Desfrancois, et al., 2000Dipole bound state; B

Ionization energy determinations

IE (eV) Method Reference Comment
7.7602 ± 0.0006LSHager and Wallace, 1988LL
7.7610 ± 0.0006PEHager, Ivanco, et al., 1985LBLHLM
7.90EICorval, 1979LLK
8.29 ± 0.05EIThorstad and Undheim, 1974LLK
7.78PEDewar, Harget, et al., 1970RDSH
7.75 ± 0.05PEEland, 1969RDSH
7.91PEKovac, Klasinc, et al., 1980Vertical value; LLK
7.92 ± 0.05PEDomelsmith, Munchausen, et al., 1977Vertical value; LLK
7.75 ± 0.015PEGusten, Klasinc, et al., 1976Vertical value; LLK
7.87PEDolby, Hanson, et al., 1976Vertical value; LLK

De-protonation reactions

C8H6N- + Hydrogen cation = Indole

By formula: C8H6N- + H+ = C8H7N

Quantity Value Units Method Reference Comment
Δr351.9 ± 2.5kcal/molTDEqMeot-ner, Liebman, et al., 1988gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Δr349.2 ± 2.1kcal/molG+TSTaft and Bordwell, 1988gas phase; B
Quantity Value Units Method Reference Comment
Δr344.1 ± 2.0kcal/molTDEqMeot-ner, Liebman, et al., 1988gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.; B
Δr341.9 ± 2.0kcal/molIMRETaft and Bordwell, 1988gas phase; B

Ion clustering data

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, IR Spectrum, UV/Visible spectrum, 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

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

MeCO2 anion + Indole = (MeCO2 anion • Indole)

By formula: C2H3O2- + C8H7N = (C2H3O2- • C8H7N)

Quantity Value Units Method Reference Comment
Δr27.9 ± 1.0kcal/molTDAsMeot-ner, 1988gas phase; B,M
Quantity Value Units Method Reference Comment
Δr30.4cal/mol*KPHPMSMeot-ner, 1988gas phase; M
Quantity Value Units Method Reference Comment
Δr18.8 ± 1.0kcal/molTDAsMeot-ner, 1988gas phase; B

IR Spectrum

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, UV/Visible spectrum, 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: NIST Mass Spectrometry Data Center, William E. Wallace, director

Gas Phase Spectrum

Notice: This spectrum may be better viewed with a Javascript and HTML 5 enabled browser.

IR spectrum
For Zoom
1.) Enter the desired X axis range (e.g., 100, 200)
2.) Check here for automatic Y scaling
3.) Press here to zoom

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

Additional Data

View image of digitized spectrum (can be printed in landscape orientation).

View spectrum image in SVG format.

Download spectrum in JCAMP-DX format.

Owner NIST Standard Reference Data Program
Collection (C) 2018 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.
Origin Sadtler Research Labs Under US-EPA Contract
State gas

This IR spectrum is from the NIST/EPA Gas-Phase Infrared Database .


UV/Visible spectrum

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, 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: Victor Talrose, Eugeny B. Stern, Antonina A. Goncharova, Natalia A. Messineva, Natalia V. Trusova, Margarita V. Efimkina

Spectrum

Notice: This spectrum may be better viewed with a Javascript and HTML 5 enabled browser.

UVVis spectrum
For Zoom
1.) Enter the desired X axis range (e.g., 100, 200)
2.) Check here for automatic Y scaling
3.) Press here to zoom

Additional Data

View image of digitized spectrum (can be printed in landscape orientation).

View spectrum image in SVG format.

Download spectrum in JCAMP-DX format.

Source Plieninger, Hobel, et al., 1963
Owner INEP CP RAS, NIST OSRD
Collection (C) 2007 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.
Origin INSTITUTE OF ENERGY PROBLEMS OF CHEMICAL PHYSICS, RAS
Source reference RAS UV No. 263
Instrument n.i.g.
Melting point 52.5
Boiling point 254

References

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, UV/Visible spectrum, Notes

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

Good, 1972
Good, W.D., Enthalpies of combustion of nine organic nitrogen compounds related to petroleum, J. Chem. Eng. Data, 1972, 17, 28-31. [all data]

Zimmerman and Geisenfelder, 1961
Zimmerman, H.; Geisenfelder, H., Uber die Mesomerieenergie von Azolen, Z. Electrochem., 1961, 65, 368-371. [all data]

Stern and Klebs, 1933
Stern, A.; Klebs, G., Calorimetrische Bestimmungen bei einfachen und mehrkernigen Pyrrolderivaten, Ann., 1933, 504, 287-297. [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]

Weast and Grasselli, 1989
CRC Handbook of Data on Organic Compounds, 2nd Editon, Weast,R.C and Grasselli, J.G., ed(s)., CRC Press, Inc., Boca Raton, FL, 1989, 1. [all data]

Cooper, Crowne, et al., 1967
Cooper, A.R.; Crowne, C.W.P.; Farrell, P.G., Gas-Liquid Chromatographic Studies of Electron-Donor-Acceptor Systems, Trans. Faraday Soc., 1967, 63, 447. [all data]

Lecat, 1947
Lecat, M., Some azeotropes of which one constituant is heterocyclic nitrogen, Ann. Soc. Sci. Bruxelles, Ser. 1, 1947, 61, 73. [all data]

Adkins and Coonradt, 1941
Adkins, H.; Coonradt, H.L., The Selective Hydrogenation of Derivatives of Pyrrole, Indole, Carbazole and Acridine, J. Am. Chem. Soc., 1941, 63, 1563-70. [all data]

Ribeiro da Silva, Cabral, et al., 2008
Ribeiro da Silva, Manuel A.V.; Cabral, Joana I.T.A.; Gomes, Jose R.B., Experimental and Computational Study on the Molecular Energetics of Indoline and Indole, J. Phys. Chem. A, 2008, 112, 47, 12263-12269, https://doi.org/10.1021/jp8065212 . [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [all data]

Arshadi, 1974
Arshadi, Mohammed R., Determination of heats of sublimation of organic compounds by a mass spectrometric--knudsen effusion method, J. Chem. Soc., Faraday Trans. 1, 1974, 70, 0, 1569, https://doi.org/10.1039/f19747001569 . [all data]

Aihara, 1955
Aihara, A., J. Chem. Soc. Jpn. Pure Chem. Sect., 1955, 76, 497. [all data]

Serpinskii, Voitkevich, et al., 1954
Serpinskii, V.V.; Voitkevich, S.A.; Lyuboshits, N.Y., Zh. Fiz. Khim., 1954, 28, 810. [all data]

Jones, 1960
Jones, A.H., Sublimation Pressure Data for Organic Compounds., J. Chem. Eng. Data, 1960, 5, 2, 196-200, https://doi.org/10.1021/je60006a019 . [all data]

Meot-ner, Liebman, et al., 1988
Meot-ner, M.; Liebman, J.F.; Kafafi, S.A., Ionic Probes of Aromaticity in Annelated Rings, J. Am. Chem. Soc., 1988, 110, 18, 5937, https://doi.org/10.1021/ja00226a001 . [all data]

Kiefer, Zhang, et al., 1997
Kiefer, J.H.; Zhang, Q.; Kern, R.D.; Yao, J.; Jursic, B., Pyrolysis of Aromatic Azines: Pyrazine, Pyrimidine, and Pyridine, J. Phys. Chem. A, 1997, 101, 38, 7061, https://doi.org/10.1021/jp970211z . [all data]

Taft and Bordwell, 1988
Taft, R.W.; Bordwell, F.G., Structural and Solvent Effects Evaluated from Acidities Measured in Dimethyl Sulfoxide and in the Gas Phase, Acc. Chem. Res., 1988, 21, 12, 463, https://doi.org/10.1021/ar00156a005 . [all data]

Meot-ner, 1988
Meot-ner, M., Ionic Hydrogen Bond and Ion Solvation. 6. Interaction Energies of the Acetate Ion with Organic Molecules. Comparison of CH3COO- with Cl-, CN-, and SH-, J. Am. Chem. Soc., 1988, 110, 12, 3854, https://doi.org/10.1021/ja00220a022 . [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]

Carles, Desfrancois, et al., 2000
Carles, S.; Desfrancois, C.; Schermann, J.P.; Smith, D.M.A.; Adamowicz, L., Structures and electron affinities of indole-(water)(N) clusters, J. Chem. Phys., 2000, 112, 8, 3726-3734, https://doi.org/10.1063/1.480938 . [all data]

Hager and Wallace, 1988
Hager, J.W.; Wallace, S.C., Two-laser photoionization supersonic jet mass spectrometry of aromatic molecules, Anal. Chem., 1988, 60, 5. [all data]

Hager, Ivanco, et al., 1985
Hager, J.; Ivanco, M.; Smith, M.A.; Wallace, S.C., Solvation effects in jet-cooled Van der Waals Clusters: Two-color threshold photoionization spectroscopy of indole, indole-argon, indole-methane, indole-water and indole-methanol, Chem. Phys. Lett., 1985, 113, 503. [all data]

Corval, 1979
Corval, M., Elimination sous impact electronique de HCN et H a partir de l'Indole. Comparaison avec l'Indolizine, Org. Mass Spectrom., 1979, 14, 213. [all data]

Thorstad and Undheim, 1974
Thorstad, O.; Undheim, K., Mass spectrometry of onium compounds. XXIV. Ionisation potential in structure analysis of pyridodiazo-oxides, Chem. Scr., 1974, 6, 222. [all data]

Dewar, Harget, et al., 1970
Dewar, M.J.S.; Harget, A.J.; Trinajstic, N.; Worley, S.D., Ground states of conjugated molecules-XXI.Benzofurans and benzopyrroles, Tetrahedron, 1970, 26, 4505. [all data]

Eland, 1969
Eland, J.H.D., Photoelectron spectra of conjugated hydrocarbons and heteromolecules, Intern. J. Mass Spectrom. Ion Phys., 1969, 2, 471. [all data]

Kovac, Klasinc, et al., 1980
Kovac, B.; Klasinc, L.; Stanovnik, B.; Tisler, M., Photoelectron spectroscopy of J. Heterocycl. Chem.. Azaindenes azaindolizines (1), J. Heterocycl. Chem., 1980, 17, 689. [all data]

Domelsmith, Munchausen, et al., 1977
Domelsmith, L.N.; Munchausen, L.L.; Houk, K.N., Photoelectron spectra of psychotropic drugs. 1. Phenethylamines, tryptamines, and LSD, J. Am. Chem. Soc., 1977, 99, 4311. [all data]

Gusten, Klasinc, et al., 1976
Gusten, H.; Klasinc, L.; Ruscic, B., Photoelectron spectroscopy of J. Heterocycl. Chem.. Indene analogs, Z. Naturforsch. A:, 1976, 31, 1051. [all data]

Dolby, Hanson, et al., 1976
Dolby, L.J.; Hanson, G.; Koenig, T., The He I photoelectron spectra of N-methylisoindole and N-methylindole, J. Org. Chem., 1976, 41, 3537. [all data]

Plieninger, Hobel, et al., 1963
Plieninger, H.; Hobel, M.; Liede, V., Synthese des 4-Dimethylallyl-tryptophans sowie der Tryptophan-essigsaure-(4), Chem. Ber., 1963, 96, 1618-1629. [all data]


Notes

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, IR Spectrum, UV/Visible spectrum, References