1,4,7,10,13,16-Hexaoxacyclooctadecane

Formula: C₁₂H₂₄O₆
Molecular weight: 264.3154
IUPAC Standard InChI: InChI=1S/C12H24O6/c1-2-14-5-6-16-9-10-18-12-11-17-8-7-15-4-3-13-1/h1-12H2
IUPAC Standard InChIKey: XEZNGIUYQVAUSS-UHFFFAOYSA-N
CAS Registry Number: 17455-13-9
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: Ethylene oxide cyclic hexamer; 18-Crown-6; 18-Crown-6 ether; Crown ether 18-crown-6
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Condensed phase thermochemistry data

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

Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-1687.8 ± 1.8	kcal/mol	Ccb	Moses and Larson, 1980	Corresponding Δ_fHº_liquid = -260.59 kcal/mol (simple calculation by NIST; no Washburn corrections)
Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_solid	-258.39 ± 0.67	kcal/mol	Ccb	Vasil'ev, Borodin, et al., 1992	Authors Hf298_condensed=-1037.0±2.8 kJ/mol
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_solid	-1690.0 ± 1.2	kcal/mol	Ccb	Vasil'ev, Borodin, et al., 1992	Authors Hf298_condensed=-1037.0±2.8 kJ/mol; Corresponding Δ_fHº_solid = -258.39 kcal/mol (simple calculation by NIST; no Washburn corrections)

Reaction thermochemistry data

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Data compiled as indicated in comments:
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias
RCD - Robert C. Dunbar

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Individual Reactions

C₄H₅N₂⁺ + 1,4,7,10,13,16-Hexaoxacyclooctadecane = (C₄H₅N₂⁺ • )

By formula: C₄H₅N₂⁺ + C₁₂H₂₄O₆ = (C₄H₅N₂⁺ • C₁₂H₂₄O₆)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	42. ± 4.	kcal/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	44.	cal/mol*K	N/A	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
16.	600.	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

C₅H₆N⁺ + 1,4,7,10,13,16-Hexaoxacyclooctadecane = (C₅H₆N⁺ • )

By formula: C₅H₆N⁺ + C₁₂H₂₄O₆ = (C₅H₆N⁺ • C₁₂H₂₄O₆)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	42. ± 4.	kcal/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	44.	cal/mol*K	N/A	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
16.	550.	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

C₆H₁₄N⁺ + 1,4,7,10,13,16-Hexaoxacyclooctadecane = (C₆H₁₄N⁺ • )

By formula: C₆H₁₄N⁺ + C₁₂H₂₄O₆ = (C₆H₁₄N⁺ • C₁₂H₂₄O₆)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	48. ± 4.	kcal/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	38.	cal/mol*K	N/A	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
23.	670.	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

C₃H₁₀N⁺ + 1,4,7,10,13,16-Hexaoxacyclooctadecane = (C₃H₁₀N⁺ • )

By formula: C₃H₁₀N⁺ + C₁₂H₂₄O₆ = (C₃H₁₀N⁺ • C₁₂H₂₄O₆)

Bond type: Hydrogen bonds with polydentate bonding in positive ions

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	41.	kcal/mol	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M
Quantity	Value	Units	Method	Reference	Comment
Δ_rS°	40.	cal/mol*K	N/A	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
18.	569.	PHPMS	Meot-Ner (Mautner), 1983	gas phase; Entropy change calculated or estimated; M

+ 1,4,7,10,13,16-Hexaoxacyclooctadecane = ( • )

By formula: Na⁺ + C₁₂H₂₄O₆ = (Na⁺ • C₁₂H₂₄O₆)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	70.7 ± 4.5	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD
Δ_rH°	71.7 ± 4.5	kcal/mol	CIDT	More, Ray, et al., 1999	RCD

Free energy of reaction

Δ_rG° (kcal/mol)	T (K)	Method	Reference	Comment
0.0	0.	CIDT	Rodgers and Armentrout, 2000	RCD
0.0	298.	CIDT	More, Ray, et al., 1999	RCD

+ 1,4,7,10,13,16-Hexaoxacyclooctadecane = ( • )

By formula: Cs⁺ + C₁₂H₂₄O₆ = (Cs⁺ • C₁₂H₂₄O₆)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	40.2 ± 2.2	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD

+ 1,4,7,10,13,16-Hexaoxacyclooctadecane = ( • )

By formula: Rb⁺ + C₁₂H₂₄O₆ = (Rb⁺ • C₁₂H₂₄O₆)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	45.7 ± 3.1	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD

+ 1,4,7,10,13,16-Hexaoxacyclooctadecane = ( • )

By formula: K⁺ + C₁₂H₂₄O₆ = (K⁺ • C₁₂H₂₄O₆)

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	56.2 ± 3.1	kcal/mol	CIDT	Rodgers and Armentrout, 2000	RCD

Gas phase ion energetics data

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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

Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	231.1	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	217.4	kcal/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.9	PE	Baker, Armen, et al., 1983	LBLHLM
9.7	PE	Baker, Armen, et al., 1983	Vertical value; LBLHLM
9.70	PE	Kajitani, Sugimori, et al., 1979	Vertical value; LLK

References

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

Moses and Larson, 1980
Moses, D.J.; Larson, J.W., Electrostatic ring strain in crown ethers, Abstract of papers, 179th ACS National Meeting, Houston, TX, 1980, 984. [all data]

Vasil'ev, Borodin, et al., 1992
Vasil'ev, V.P.; Borodin, V.A.; Kopnyshev, S.B., Standard enthalpies of formation of certain crown-ethers, Russ. J. Phys. Chem. (Engl. Transl.), 1992, 66, 585-587, In original 1104. [all data]

Meot-Ner (Mautner), 1983
Meot-Ner (Mautner), M., The Ionic Hydrogen Bond. 3. Multiple and -CH+...O- Bonds. Complexes of Ammonium Ions with Polyethers and Crown Ethers, J. Am. Chem. Soc., 1983, 105, 15, 4912, https://doi.org/10.1021/ja00353a012 . [all data]

Rodgers and Armentrout, 2000
Rodgers, M.T.; Armentrout, P.B., Noncovalent Metal-Ligand Bond Energies as Studied by Threshold Collision-Induced Dissociation, Mass Spectrom. Rev., 2000, 19, 4, 215, https://doi.org/10.1002/1098-2787(200007)19:4<215::AID-MAS2>3.0.CO;2-X . [all data]

More, Ray, et al., 1999
More, M.B.; Ray, D.; Armentrout, P.B., Intrinsic Affinities of Alkali Cations for 15-Crown-5 and 18-Crown-6: Bond Dissociation Energies of Gas-Phase M+-Crown Ether Complexes, J. Am. Chem. Soc., 1999, 121, 2, 417, https://doi.org/10.1021/ja9823159 . [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]

Baker, Armen, et al., 1983
Baker, A.D.; Armen, G.H.; Funaro, S., Oral levels of crown ethers and related macrocycles studies by ultraviolet photoelectron spectroscopy: Relationship to complexation studies, J. Chem. Soc. Dalton Trans., 1983, 2519. [all data]

Kajitani, Sugimori, et al., 1979
Kajitani, M.; Sugimori, A.; Sato, N.; Seki, K.; Inokuchi, H.; Harada, Y., Ultraviolet photoelectron spectra of crown ethers, Bull. Chem. Soc. Jpn., 1979, 52, 2199. [all data]

Notes

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

Symbols used in this document:

T	Temperature
Δ_cH°_liquid	Enthalpy of combustion of liquid at standard conditions
Δ_cH°_solid	Enthalpy of combustion of solid at standard conditions
Δ_fH°_solid	Enthalpy of formation of solid at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions
Δ_rS°	Entropy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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