(E)-1,2-Difluoroethylene

Formula: C₂H₂F₂
Molecular weight: 64.0341
CAS Registry Number: 1630-78-0
Information on this page:
Data at other public NIST sites:
- Gas Phase Kinetics Database
Options:
- Switch to calorie-based units

Reaction thermochemistry data

Go To: Top, Gas phase ion energetics data, References, Notes

Data compiled by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

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

C₂H₂F₂ =

By formula: C₂H₂F₂ = C₂H₂F₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	-4.52 ± 0.50	kJ/mol	Eqk	Craig, Piper, et al., 1971	gas phase

= C₂H₂F₂

By formula: C₂H₂F₂ = C₂H₂F₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	3.9	kJ/mol	Eqk	Craig and Entemann, 1961	gas phase

Gas phase ion energetics data

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

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias

Data compiled as indicated in comments:
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

View reactions leading to C₂H₂F₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	688.6	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	657.9	kJ/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
10.15	PI	Frenking, Koch, et al., 1984	LBLHLM
10.21 ± 0.02	PE	Bieri, Niessen, et al., 1981	LLK
10.15 ± 0.02	PI	Jochims, Lohr, et al., 1979	LLK
10.21	PE	Sell, Mintz, et al., 1978	LLK
10.63 ± 0.02	PE	Bieri, Niessen, et al., 1981	Vertical value; LLK
10.38 ± 0.02	PE	Sell and Kuppermann, 1979	Vertical value; LLK
10.39 ± 0.02	PE	Jochims, Lohr, et al., 1979	Vertical value; LLK
10.38	PE	Brundle, Robin, et al., 1972	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
CF⁺	14.45	CH₂F	PI	Frenking, Koch, et al., 1984	LBLHLM
CF⁺	14.5 ± 0.1	?	PI	Stadelmann and Vogt, 1980	LLK
CF⁺	14.45 ± 0.03	CH₂F	PI	Jochims, Lohr, et al., 1979	LLK
CHF⁺	18.1 ± 0.2	CHF	PI	Stadelmann and Vogt, 1980	LLK
CH₂F⁺	14.35	CF	PI	Frenking, Koch, et al., 1984	LBLHLM
CH₂F⁺	14.3 ± 0.1	CF	PI	Stadelmann and Vogt, 1980	LLK
CH₂F⁺	14.35 ± 0.03	CF	PI	Jochims, Lohr, et al., 1979	LLK
C₂HF⁺	13.70	HF	PI	Frenking, Koch, et al., 1984	LBLHLM
C₂HF⁺	13.7 ± 0.1	HF	PI	Stadelmann and Vogt, 1980	LLK
C₂HF⁺	13.70 ± 0.03	HF	PI	Jochims, Lohr, et al., 1979	LLK
C₂HF₂⁺	15.4 ± 0.2	H	PI	Stadelmann and Vogt, 1980	LLK
C₂H₂⁺	18.3 ± 0.2	?	PI	Stadelmann and Vogt, 1980	LLK
C₂H₂F⁺	13.97	F	PI	Frenking, Koch, et al., 1984	LBLHLM
C₂H₂F⁺	13.9 ± 0.1	F	PI	Stadelmann and Vogt, 1980	LLK
C₂H₂F⁺	13.95 ± 0.03	F	PI	Jochims, Lohr, et al., 1979	LLK

References

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

Craig, Piper, et al., 1971
Craig, N.C.; Piper, L.G.; Wheeler, V.L., Thermodynamics of cis-trans isomerizations. II. The 1-chloro-2-fluoroethylenes, 1,2-difluorocyclopropanes, and related molecules, J. Phys. Chem., 1971, 75, 1453-1460. [all data]

Craig and Entemann, 1961
Craig, N.C.; Entemann, E.A., Thermodynamics of cis-trans isomerizations. The 1,2-difluoroethylenes, J. Am. Chem. Soc., 1961, 83, 3047-3050. [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]

Frenking, Koch, et al., 1984
Frenking, G.; Koch, W.; Schaale, M.; Baumgartel, H., The unimolecular decay of difluoroethene cations. An experimental and quantum-chemical study, Int. J. Mass Spectrom. Ion Phys., 1984, 61, 305. [all data]

Bieri, Niessen, et al., 1981
Bieri, G.; Niessen, W.V.; Asbrink, L.; Svensson, A., The He(II) photoelectron spectra of the fluorosubstituted ethylenes and their analysis by the green's function method, Chem. Phys., 1981, 60, 61. [all data]

Jochims, Lohr, et al., 1979
Jochims, H.-W.; Lohr, W.; Baumgartel, H., Photoreactions of small organic molecules. VI. Photoionization processes of difluoroethylenes, Nouv. J. Chim., 1979, 3, 109. [all data]

Sell, Mintz, et al., 1978
Sell, J.A.; Mintz, D.M.; Kupperman, A., Photoelectron angular distributions of carbon-carbon π electrons in ethylene, benzene, and their fluorinated derivatives, Chem. Phys. Lett., 1978, 58, 601. [all data]

Sell and Kuppermann, 1979
Sell, J.A.; Kuppermann, A., Variable angle photoelectron spectroscopy of the fluoroethylenes, J. Chem. Phys., 1979, 71, 4703. [all data]

Brundle, Robin, et al., 1972
Brundle, C.R.; Robin, M.B.; Kuebler, N.A.; Basch, H., Perfluoro effect in photoelectron spectroscopy. I. Nonaromatic molecules, J. Am. Chem. Soc., 1972, 94, 1451. [all data]

Stadelmann and Vogt, 1980
Stadelmann, J.P.; Vogt, J., A photoelectron-photoion coincidence study of cis- and trans- difluoroethene, Int. J. Mass Spectrom. Ion Phys., 1980, 35, 83. [all data]

Notes

Go To: Top, Reaction thermochemistry data, Gas phase ion energetics data, References

Symbols used in this document:

AE Appearance energy

Δ_rH° Enthalpy of reaction at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein have been selected on the basis of sound scientific judgment. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the Database.
Customer support for NIST Standard Reference Data products.

AE	Appearance energy
Δ_rH°	Enthalpy of reaction at standard conditions