Acetylene

Formula: C₂H₂
Molecular weight: 26.0373
IUPAC Standard InChI: InChI=1S/C2H2/c1-2/h1-2H
IUPAC Standard InChIKey: HSFWRNGVRCDJHI-UHFFFAOYSA-N
CAS Registry Number: 74-86-2
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: Ethyne; Ethine; Narcylen; C2H2; Acetylen; UN 1001; Vinylene
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Phase change data

Go To: Top, Henry's Law data, Gas phase ion energetics data, References, Notes

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
CAL - James S. Chickos, William E. Acree, Jr., Joel F. Liebman, Students of Chem 202 (Introduction to the Literature of Chemistry), University of Missouri -- St. Louis

Quantity	Value	Units	Method	Reference	Comment
T_boil	189.	K	N/A	Buckingham and Donaghy, 1982	BS
T_boil	189.6	K	N/A	Maass and Wright, 1921	Uncertainty assigned by TRC = 0.3 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_fus	171.65	K	N/A	Morehouse and Maass, 1931	Uncertainty assigned by TRC = 0.5 K; TRC
T_fus	191.4	K	N/A	Maass and Russell, 1918	Uncertainty assigned by TRC = 1. K; TRC
T_fus	191.65	K	N/A	McIntosh, 1907	Uncertainty assigned by TRC = 0.5 K; TRC
Quantity	Value	Units	Method	Reference	Comment
T_triple	192.4	K	N/A	Clark and Din, 1950	Uncertainty assigned by TRC = 0.5 K; TRC
T_triple	191.35	K	N/A	Maass and Wright, 1921	Uncertainty assigned by TRC = 0.3 K; TRC
Quantity	Value	Units	Method	Reference	Comment
P_triple	1.2825	bar	N/A	Clark and Din, 1950	Uncertainty assigned by TRC = 0.0039 bar; TRC
Quantity	Value	Units	Method	Reference	Comment
T_c	308.3 ± 0.1	K	N/A	Tsonopoulos and Ambrose, 1996
T_c	308.35	K	N/A	Goloborod'ko and Khodeeva, 1972	Visual, as Goloborod'ko and Khodeeva Zh.Fiz.Khim. 1969,43,1340; TRC
T_c	308.66	K	N/A	Khodeeva, 1966	TRC
T_c	309.7	K	N/A	Maass and Wright, 1921	Uncertainty assigned by TRC = 0.6 K; TRC
Quantity	Value	Units	Method	Reference	Comment
P_c	61.38 ± 0.10	bar	N/A	Tsonopoulos and Ambrose, 1996
Quantity	Value	Units	Method	Reference	Comment
V_c	0.1122	l/mol	N/A	Tsonopoulos and Ambrose, 1996
V_c	0.113	l/mol	N/A	Khodeeva, 1966	Visual, samples thoroughly purified; TRC
Quantity	Value	Units	Method	Reference	Comment
ρ_c	8.91 ± 0.010	mol/l	N/A	Tsonopoulos and Ambrose, 1996

Enthalpy of vaporization

Δ_vapH (kJ/mol)	Temperature (K)	Method	Reference	Comment
16.3	273.	A	Stephenson and Malanowski, 1987	Based on data from 258. to 308. K.; AC
16.7	207.	A	Stephenson and Malanowski, 1987	Based on data from 192. to 308. K.; AC
16.7	210.	A	Stephenson and Malanowski, 1987	Based on data from 192. to 225. K.; AC
17.0	214.	N/A	Reid, 1972	AC
16.4	230.	N/A	Ambrose and Townsend, 1964	Based on data from 215. to 308. K.; AC
16.8	200.	N/A	Ambrose, 1956	Based on data from 193. to 207. K. See also Boublik, Fried, et al., 1984.; AC

Antoine Equation Parameters

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

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Temperature (K)	A	B	C	Reference	Comment
214.64 to 308.33	4.66141	909.079	7.947	Ambrose and Townsend, 1964, 2	Coefficents calculated by NIST from author's data.
192.59 to 206.30	4.19598	699.53	-21.47	Ambrose, 1956, 2	Coefficents calculated by NIST from author's data.

Enthalpy of sublimation

Δ_subH (kJ/mol)	Temperature (K)	Method	Reference	Comment
23.5	130.	A	Stephenson and Malanowski, 1987	Based on data from 98. to 145. K.; AC
21.8	162.	N/A	Jones, 1960	Based on data from 133. to 191. K.; AC
25.2	193.	N/A	Ambrose, 1956	Based on data from 151. to 193. K.; AC
22.7	160.	A	Stull, 1947	Based on data from 130. to 189. K.; AC
22.1	129.	A	Burbo, 1943	Based on data from 89. to 169. K.; AC

Enthalpy of fusion

Δ_fusH (kJ/mol)	Temperature (K)	Reference	Comment
3.76	192.4	Miskiewicz, Rieser, et al., 2010	AC

Entropy of fusion

Δ_fusS (J/mol*K)	Temperature (K)	Reference	Comment
17.8	142.7	Miskiewicz, Rieser, et al., 1976	CAL
19.5	192.4	Miskiewicz, Rieser, et al., 1976	CAL

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:

Henry's Law data

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

Data compiled by: Rolf Sander

Henry's Law constant (water solution)

k_H(T) = k°_H exp(d(ln(k_H))/d(1/T) ((1/T) - 1/(298.15 K)))
k°_H = Henry's law constant for solubility in water at 298.15 K (mol/(kg*bar))
d(ln(k_H))/d(1/T) = Temperature dependence constant (K)

k°_H (mol/(kg*bar))	d(ln(k_H))/d(1/T) (K)	Method	Reference	Comment
0.039		Q	N/A	missing citation give several references for the Henry's law constants but don't assign them to specific species.
0.041	1800.	L	N/A
0.042		V	N/A

Gas phase ion energetics data

Go To: Top, Phase change data, Henry's Law data, References, Notes

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
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
LL - Sharon G. Lias and Joel F. Liebman

View reactions leading to C₂H₂⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	11.400 ± 0.002	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	641.4	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	616.7	kJ/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
11.41 ± 0.01	EI	Plessis and Marmet, 1986	LBLHLM
11.40	PI	Hayaishi, Iwata, et al., 1982	LBLHLM
11.4	EVAL	Rosmus, Botschwina, et al., 1981	LLK
11.40	PE	Kimura, Katsumata, et al., 1981	LLK
11.40	PE	Bieri, Schmelzer, et al., 1980	LLK
11.4 ± 0.1	EI	Suzuki and Maeda, 1978	LLK
11.4 ± 0.1	EI	Suzuki and Maeda, 1977	LLK
11.40 ± 0.02	PE	Bieri, Burger, et al., 1977	LLK
~11.3	EI	Van Veen and Plantenga, 1976	LLK
11.37 ± 0.05	EI	Reeher, Flesch, et al., 1976	LLK
11.403 ± 0.0003	PE	Carlier, Dubois, et al., 1975	LLK
11.394 ± 0.005	PI	Parr and Taylor, 1973	LLK
11.398 ± 0.005	PI	Dibeler and Walker, 1973	LLK
11.40	PE	Brogli, Heilbronner, et al., 1973	LLK
11.39 ± 0.02	EI	Lossing, 1970	RDSH
11.395 ± 0.015	PI	Omura, Kaneko, et al., 1969	RDSH
11.39 ± 0.05	EI	Williams and Hamill, 1968	RDSH
11.41 ± 0.01	EI	Collins, Winters, et al., 1968	RDSH
11.40 ± 0.01	PE	Baker and Turner, 1968	RDSH
11.400 ± 0.005	PI	Brehm, 1966	RDSH
11.396 ± 0.003	PI	Nicholson, 1965	RDSH
11.40 ± 0.02	EI	Melton and Hamill, 1964	RDSH
11.406 ± 0.006	PI	Dibeler and Reese, 1964	RDSH
11.41 ± 0.01	PI	Watanabe and Namioka, 1956	RDSH
11.2 ± 0.1	EI	Kusch, Hustrulid, et al., 1937	RDSH
11.41	S	Price, 1935	RDSH
11.49	PE	Bieri and Asbrink, 1980	Vertical value; LLK
11.43	PE	Cavell and Allison, 1978	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C⁺	21.20 ± 0.05	CH₂	EI	Locht and Davister, 1995	LL
C⁺	24. ± 1.	?	PI	Cooper, Ibuki, et al., 1988	LL
C⁺	20.43 ± 0.05	CH₂	EI	Plessis and Marmet, 1986	LBLHLM
C⁺	22.5 ± 0.3	C⁺²H	EI	Suzuki and Maeda, 1977	LLK
C⁺	23.6	?	EI	Bloch, 1963	RDSH
C⁺	24.5 ± 1.0	C⁺²H	EI	Kusch, Hustrulid, et al., 1937	RDSH
CH⁺	20.85 ± 0.05	CH	EI	Davister and Locht, 1995	LL
CH⁺	20.54 ± 0.05	CH	EI	Plessis and Marmet, 1986	LBLHLM
CH⁺	23.9 ± 0.2	C+H	EI	Plessis and Marmet, 1986	LBLHLM
CH⁺	24.1	C+H	PI	Hayaishi, Iwata, et al., 1982	LBLHLM
CH⁺	20.7 ± 0.1	CH	PI	Hayaishi, Iwata, et al., 1982	LBLHLM
CH⁺	20.9 ± 0.2	CH	EI	Suzuki and Maeda, 1977	LLK
CH⁺	21.5 ± 0.2	CH	EI	Kloster-Jensen, Pascual, et al., 1970	RDSH
CH⁺	21.9	CH	EI	Haney and Franklin, 1968	RDSH
CH⁺	22.2 ± 0.5	CH	EI	Kusch, Hustrulid, et al., 1937	RDSH
CH₂⁺	19.74 ± 0.20	C	EI	Locht and Davister, 1995	LL
CH₂⁺	18.17 ± 0.09	C^-	EI	Plessis and Marmet, 1986	LBLHLM
CH₂⁺	19.40 ± 0.12	C	EI	Plessis and Marmet, 1986	LBLHLM
CH₂⁺	19.4 ± 0.1	C	PI	Hayaishi, Iwata, et al., 1982	LBLHLM
CH₂⁺	20.5 ± 0.2	?	EI	Suzuki and Maeda, 1977	LLK
CH₂⁺	21.	C	EI	Franklin and Munson, 1965	RDSH
C₂⁺	19. ± 1.	H₂	CIEL	Reid, Ballantine, et al., 1995	LL
C₂⁺	18.44 ± 0.07	H₂	EI	Locht and Davister, 1995	LL
C₂⁺	22.60 ± 0.12	2H	EI	Plessis and Marmet, 1986	LBLHLM
C₂⁺	18.16 ± 0.05	H₂	EI	Plessis and Marmet, 1986	LBLHLM
C₂⁺	18.1 ± 0.1	H₂	PI	Hayaishi, Iwata, et al., 1982	LBLHLM
C₂⁺	22.7 ± 0.1	2H	PI	Hayaishi, Iwata, et al., 1982	LBLHLM
C₂⁺	19.2 ± 0.2	?	EI	Suzuki and Maeda, 1977	LLK
C₂⁺	23.6	2H?	EI	Momigny and Derouane, 1968	RDSH
C₂⁺	19.5	H₂	EI	Bloch, 1963	RDSH
C₂⁺	23.8	2H?	EI	Bloch, 1963	RDSH
C₂⁺	22.7	2H?	EI	Field, Franklin, et al., 1957	RDSH
C₂⁺	18.2	H₂	EI	Field, Franklin, et al., 1957	RDSH
C₂⁺	23.3 ± 0.5	2H?	EI	Coats and Anderson, 1957	RDSH
C₂⁺	23.8 ± 0.3	2H	EI	Kusch, Hustrulid, et al., 1937	RDSH
C₂H⁺	17.35 ± 0.04	H	PIPECO	Servais and Locht, 1995	LL
C₂H⁺	17.360	H	PIPECO	Weitzel, Mahnert, et al., 1994	LL
C₂H⁺	17.30 ± 0.08	H	EI	Davister and Locht, 1994	LL
C₂H⁺	17.33 ± 0.05	H	PIPECO	Norwood and Ng, 1989	LL
C₂H⁺	16.70 ± 0.10	H	EI	Plessis and Marmet, 1986	LBLHLM
C₂H⁺	16.8 ± 0.1	H	PI	Hayaishi, Iwata, et al., 1982	LBLHLM
C₂H⁺	16.79 ± 0.03	H	PI	Ono and Ng, 1981	LLK
C₂H⁺	17.3	H	PIPECO	Eland, 1979	LLK
C₂H⁺	17.5 ± 0.1	H	EI	Suzuki and Maeda, 1977	LLK
C₂H⁺	17.36 ± 0.01	H	PI	Dibeler, Walker, et al., 1973	LLK
C₂H⁺	17.22	H	PI	Botter, Dibeler, et al., 1966	RDSH
C₂H⁺	17.3	H	EI	Field, Franklin, et al., 1957	RDSH
C₂H⁺	17.8 ± 0.2	H	EI	Kusch, Hustrulid, et al., 1937	RDSH
H⁺	18.83 ± 0.23	C₂H	EI	Davister and Locht, 1994	LL
H⁺	23. ± 1.	?	PI	Cooper, Ibuki, et al., 1988	LL
H⁺	19.35 ± 0.05	C₂H	PI	Shiromaru, Achiba, et al., 1987	LBLHLM
H⁺	20.6 ± 0.3	?	EI	Suzuki and Maeda, 1977	LLK
H⁺	21.7 ± 1.0	C₂+H	EI	Kusch, Hustrulid, et al., 1937	RDSH
H⁺	25.6 ± 1.0	CH+C	EI	Kusch, Hustrulid, et al., 1937	RDSH

De-protonation reactions

C₂H^- + = Acetylene

By formula: C₂H^- + H⁺ = C₂H₂

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	1580. ± 20.	kJ/mol	AVG	N/A	Average of 8 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	1550. ± 20.	kJ/mol	AVG	N/A	Average of 7 values; Individual data points

References

Go To: Top, Phase change data, Henry's Law data, Gas phase ion energetics data, Notes

Buckingham and Donaghy, 1982
Buckingham, J.; Donaghy, S.M., Dictionary of Organic Compounds: Fifth Edition, Chapman and Hall, New York, 1982, 1. [all data]

Maass and Wright, 1921
Maass, O.; Wright, C.H., SOME PHYSICAL PROPERTIES OF HYDROCARBONS CONTAINING TWO AND THREE CARBON ATOMS., J. Am. Chem. Soc., 1921, 43, 5, 1098-1111, https://doi.org/10.1021/ja01438a013 . [all data]

Morehouse and Maass, 1931
Morehouse, F.R.; Maass, O., The Preparationa and Physical Properties of Ethyl and Methyl Acetylene, Can. J. Res., 1931, 5, 306. [all data]

Maass and Russell, 1918
Maass, O.; Russell, J., Unsaturation and molecular compound formation, J. Am. Chem. Soc., 1918, 40, 1561-1573. [all data]

McIntosh, 1907
McIntosh, D., The physical properties of liquid and solid acetylene., J. Phys. Chem., 1907, 11, 306-17. [all data]

Clark and Din, 1950
Clark, A.M.; Din, F., Equilibria Between Solid, Liquid, and Gaseous Phases at Low Temperature binary systems acetylene - carbon dioxide, acetylene - ethylene and acetylene - ethane, Trans. Faraday Soc., 1950, 46, 901. [all data]

Tsonopoulos and Ambrose, 1996
Tsonopoulos, C.; Ambrose, D., Vapor-Liquid Critical Properties of Elements and Compounds. 6. Unsaturated Aliphatic Hydrocarbons, J. Chem. Eng. Data, 1996, 41, 645-656. [all data]

Goloborod'ko and Khodeeva, 1972
Goloborod'ko, N.P.; Khodeeva, S.M., Russ. J. Phys. Chem. (Engl. Transl.), 1972, 46, 235-7. [all data]

Khodeeva, 1966
Khodeeva, S.M., Visual Observation of Gas-Gas Mixture, Russ. J. Phys. Chem. (Engl. Transl.), 1966, 40, 1061-3. [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]

Reid, 1972
Reid, Robert C., Handbook on vapor pressure and heats of vaporization of hydrocarbons and related compounds, R. C. Wilhort and B. J. Zwolinski, Texas A Research Foundation. College Station, Texas(1971). 329 pages.$10.00, AIChE J., 1972, 18, 6, 1278-1278, https://doi.org/10.1002/aic.690180637 . [all data]

Ambrose and Townsend, 1964
Ambrose, D.; Townsend, R., Vapour pressure of acetylene, Trans. Faraday Soc., 1964, 60, 1025, https://doi.org/10.1039/tf9646001025 . [all data]

Ambrose, 1956
Ambrose, D., The vapour pressures and critical temperatures of acetylene and carbon dioxide, Trans. Faraday Soc., 1956, 52, 772, https://doi.org/10.1039/tf9565200772 . [all data]

Boublik, Fried, et al., 1984
Boublik, T.; Fried, V.; Hala, E., The Vapour Pressures of Pure Substances: Selected Values of the Temperature Dependence of the Vapour Pressures of Some Pure Substances in the Normal and Low Pressure Region, 2nd ed., Elsevier, New York, 1984, 972. [all data]

Ambrose and Townsend, 1964, 2
Ambrose, D.; Townsend, R., Vapour Pressure of Acetylene, Trans. Faraday Soc., 1964, 60, 1025-1029, https://doi.org/10.1039/tf9646001025 . [all data]

Ambrose, 1956, 2
Ambrose, D., The Vapour Pressures and Critical Temperatures of Acetylene and Carbon Dioxide, Trans. Faraday Soc., 1956, 52, 772-781, https://doi.org/10.1039/tf9565200772 . [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]

Stull, 1947
Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

Burbo, 1943
Burbo, P.Z., Russ. J. Phys. Chem., 1943, 7, 286. [all data]

Miskiewicz, Rieser, et al., 2010
Miskiewicz, Stefan; Rieser, Klaus; Dorfmüller, Thomas, Thermodynamische Untersuchungen an kondensierten Phasen, Berichte der Bunsengesellschaft für physikalische Chemie, 2010, 80, 5, 395-405, https://doi.org/10.1002/bbpc.19760800504 . [all data]

Miskiewicz, Rieser, et al., 1976
Miskiewicz, S.; Rieser, K.; Dorfmuller, T., Thermodynamische Untersuchungen an kondensierten Phasen, Ber. Bunsen-Ges. Physik. Chem., 1976, 80, 5, 395, https://doi.org/10.1002/bbpc.19760800504 . [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]

Plessis and Marmet, 1986
Plessis, P.; Marmet, P., Electroionization study of acetylene and fragment ions, Int. J. Mass Spectrom. Ion Processes, 1986, 70, 23. [all data]

Hayaishi, Iwata, et al., 1982
Hayaishi, T.; Iwata, S.; Sasanuma, M.; Ishiguro, E.; Morioka, Y.; Iida, Y.; Nakamura, M., Photoionisation mass spectrometric study of acetylene in the VUV region, J. Phys. B:, 1982, 15, 79. [all data]

Rosmus, Botschwina, et al., 1981
Rosmus, P.; Botschwina, P.; Maier, J.P., On the ionic states of vinylidene and acetylene, Chem. Phys. Lett., 1981, 84, 71. [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Bieri, Schmelzer, et al., 1980
Bieri, G.; Schmelzer, A.; Asbrink, L.; Jonsson, M., Fluorine and the fluoroderivatives of acetylene and diacetylene studied by 30.4 nm He(II) photoelectron spectroscopy, Chem. Phys., 1980, 49, 213. [all data]

Suzuki and Maeda, 1978
Suzuki, I.H.; Maeda, K., Ionization efficiency curves of acetylene by mono-energetic electron impact, Adv. Mass Spectrom., 1978, 7, 182. [all data]

Suzuki and Maeda, 1977
Suzuki, I.H.; Maeda, K., Ionization efficiency curves of acetylene by electron impact, Mass Spectrosc. (Tokyo), 1977, 25, 223. [all data]

Bieri, Burger, et al., 1977
Bieri, G.; Burger, F.; Heilbronner, E.; Maier, J.P., Valence ionization enrgies of hydrocarbons, Helv. Chim. Acta, 1977, 60, 2213. [all data]

Van Veen and Plantenga, 1976
Van Veen, E.H.; Plantenga, F.L., Low-energy electron-impact excitation spectra of acetylene, Chem. Phys. Lett., 1976, 38, 493. [all data]

Reeher, Flesch, et al., 1976
Reeher, J.R.; Flesch, G.D.; Svec, H.J., The mass spectra and ionization potentials of the neutral fragments produced during the electron bombardment of aromatic compounds, Org. Mass Spectrom., 1976, 11, 154. [all data]

Carlier, Dubois, et al., 1975
Carlier, P.; Dubois, J.E.; Masclet, P.; Mouvier, G., Spectres de photoelectrons des alcynes, J. Electron Spectrosc. Relat. Phenom., 1975, 7, 55. [all data]

Parr and Taylor, 1973
Parr, G.R.; Taylor, J.W., A photoionization mass spectrometer utilizing a high intensity molecular beam sampling system and synchrotron radiation, Rev. Sci. Instrum., 1973, 44, 1578. [all data]

Dibeler and Walker, 1973
Dibeler, V.H.; Walker, J.A., Photoionization of acetylene near threshold, Int. J. Mass Spectrom. Ion Phys., 1973, 11, 49. [all data]

Brogli, Heilbronner, et al., 1973
Brogli, F.; Heilbronner, E.; Hornung, V.; Kloster-Jensen, E., 230. Die photoelektronen-spektren methyl-substituierter Acetylene, Helv. Chim. Acta, 1973, 56, 2171. [all data]

Lossing, 1970
Lossing, F.P., Threshold ionization of acetylene by monoenergetic electron impact, Intern. J. Mass Spectrom. Ion Phys., 1970, 5, 190. [all data]

Omura, Kaneko, et al., 1969
Omura, I.; Kaneko, T.; Yamada, Y.; Tanaka, K., Mass spectrometric studies of photoionization. IV. Acetylene and propyne, J. Phys. Soc. Japan, 1969, 27, 178. [all data]

Williams and Hamill, 1968
Williams, J.M.; Hamill, W.H., Ionization potentials of molecules and free radicals and appearance potentials by electron impact in the mass spectrometer, J. Chem. Phys., 1968, 49, 4467. [all data]

Collins, Winters, et al., 1968
Collins, J.H.; Winters, R.E.; Engerholm, G.G., Fine structure in energy-distribution-difference ionizationefficiency curves, J. Chem. Phys., 1968, 49, 2469. [all data]

Baker and Turner, 1968
Baker, C.; Turner, D.W., High resolution molecular photoelectron spectroscopy. III.Acetylenes and azaacetylenes, Proc. Roy. Soc. (London), 1968, A308, 19. [all data]

Brehm, 1966
Brehm, B., Massenspektrometrische Untersuchung der Photoionisation von Molekulen, Z. Naturforsch., 1966, 21a, 196. [all data]

Nicholson, 1965
Nicholson, A.J.C., Photoionization-efficiency curves. II. False and genuine structure, J. Chem. Phys., 1965, 43, 1171. [all data]

Melton and Hamill, 1964
Melton, C.E.; Hamill, W.H., Appearance potentials by the retarding potential-difference method for secondary ions produced by excited-neutral, excited ion-neutral, and ion-neutral reactions, J. Chem. Phys., 1964, 41, 1469. [all data]

Dibeler and Reese, 1964
Dibeler, V.H.; Reese, R.M., Mass spectrometric study of photoionization. I. Apparatus and initial observations on acetylene, acetylene-d₂, benzene, and benzene-d₆, J. Res. NBS, 1964, 68A, 409. [all data]

Watanabe and Namioka, 1956
Watanabe, K.; Namioka, T., Ionization potential of propyne, J. Chem. Phys., 1956, 24, 915. [all data]

Kusch, Hustrulid, et al., 1937
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Notes

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Symbols used in this document:

AE	Appearance energy
IE (evaluated)	Recommended ionization energy
P_c	Critical pressure
P_triple	Triple point pressure
T_boil	Boiling point
T_c	Critical temperature
T_fus	Fusion (melting) point
T_triple	Triple point temperature
V_c	Critical volume
d(ln(k_H))/d(1/T)	Temperature dependence parameter for Henry's Law constant
k°_H	Henry's Law constant at 298.15K
Δ_fusH	Enthalpy of fusion
Δ_fusS	Entropy of fusion
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_subH	Enthalpy of sublimation
Δ_vapH	Enthalpy of vaporization
ρ_c	Critical density

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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