Isocyanic acid
- Formula: CHNO
- Molecular weight: 43.0247
- IUPAC Standard InChI: InChI=1S/CHNO/c2-1-3/h2H
- IUPAC Standard InChIKey: OWIKHYCFFJSOEH-UHFFFAOYSA-N
- CAS Registry Number: 75-13-8
- Chemical structure:
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Gas phase ion energetics data
Go To: Top, 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
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| IE (evaluated) | 11.595 ± 0.005 | eV | N/A | N/A | L |
| Quantity | Value | Units | Method | Reference | Comment |
| Proton affinity (review) | 180. | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
| Quantity | Value | Units | Method | Reference | Comment |
| Gas basicity | 171.8 | kcal/mol | N/A | Hunter and Lias, 1998 | HL |
Ionization energy determinations
| IE (eV) | Method | Reference | Comment |
|---|---|---|---|
| 11.595 ± 0.005 | PI | Ruscic and Berkowitz, 1994 | LL |
| 11.62 ± 0.02 | PE | Cradock, Ebsworth, et al., 1972 | LLK |
| 11.60 ± 0.01 | PE | Rowland, Eland, et al., 1968 | RDSH |
Appearance energy determinations
| Ion | AE (eV) | Other Products | Method | Reference | Comment |
|---|---|---|---|---|---|
| CHO+ | 15.52 | N | EI | Compernolle, 1975 | LLK |
| CHO+ | 15.76 ± 0.15 | N | EI | Bogan and Hand, 1971 | LLK |
| CNO+ | ≤16.532 | H | PI | Ruscic and Berkowitz, 1994 | LL |
| CNO+ | 16.66 ± 0.15 | H | EI | Bogan and Hand, 1971 | LLK |
| CNO+ | ≤16.1 | H | EI | Rowland, Eland, et al., 1968 | RDSH |
| NH+ | 17.26 ± 0.15 | CO | EI | Bogan and Hand, 1971 | LLK |
| NH+ | ≤17.7 | CO | EI | Rowland, Eland, et al., 1968 | RDSH |
| NO+ | 15.76 ± 0.15 | ? | EI | Bogan and Hand, 1971 | LLK |
De-protonation reactions
CNO- + =
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 341.18 ± 0.61 | kcal/mol | D-EA | Bradforth, Kim, et al., 1993 | gas phase; D-EA cycle requires a DH ca 4 kcal/mol weaker; B |
| ΔrH° | 344.7 ± 2.1 | kcal/mol | G+TS | Wight and Beauchamp, 1980 | gas phase; B |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔrG° | 334.74 ± 0.71 | kcal/mol | H-TS | Bradforth, Kim, et al., 1993 | gas phase; D-EA cycle requires a DH ca 4 kcal/mol weaker; B |
| ΔrG° | 338.3 ± 2.0 | kcal/mol | IMRE | Wight and Beauchamp, 1980 | gas phase; B |
References
Go To: Top, 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.
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]
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]
Notes
Go To: Top, Gas phase ion energetics data, References
- Symbols used in this document:
AE Appearance energy IE (evaluated) Recommended ionization energy 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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