Phosphoric acid, trimethyl ester

Formula: C₃H₉O₄P
Molecular weight: 140.0749
IUPAC Standard InChI: InChI=1S/C3H9O4P/c1-5-8(4,6-2)7-3/h1-3H3
IUPAC Standard InChIKey: WVLBCYQITXONBZ-UHFFFAOYSA-N
CAS Registry Number: 512-56-1
Chemical structure:
This structure is also available as a 2d Mol file or as a computed 3d SD file
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Other names: Methyl phosphate; Trimethoxyphosphine oxide; Trimethyl orthophosphate; Trimethyl phosphate; (CH3O)3PO; Methyl phosphate, (MeO)3PO; NCI-C03781; TMP; Trimethylfosfat; O,O,O-Trimethyl phosphate; NSC 58985; TMPA; TMPO
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Information on this page:
Other data available:
Data at other public NIST sites:
- Gas Phase Kinetics Database
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Phase change data

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Data compiled as indicated in comments:
AC - William E. Acree, Jr., James S. Chickos

Quantity	Value	Units	Method	Reference	Comment
Δ_vapH°	47.5	kJ/mol	CGC	Panneerselvam, Antony, et al., 2007	Based on data from 408. to 438. K.; AC

Enthalpy of vaporization

Δ_vapH (kJ/mol)	Temperature (K)	Method	Reference	Comment
48.8	311.	A	Stephenson and Malanowski, 1987	Based on data from 296. to 466. K. See also Stull, 1947.; 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
299. to 465.9	4.96817	2249.287	-12.294	Stull, 1947	Coefficents calculated by NIST from author's data.

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:
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
Proton affinity (review)	890.6	kJ/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	860.8	kJ/mol	N/A	Hunter and Lias, 1998	HL

Ionization energy determinations

IE (eV)	Method	Reference	Comment
10.0	PE	Chattorpadhyay, Findley, et al., 1981	LLK
9.99	PE	Hodges, McDonnell, et al., 1980	LLK
10.70 ± 0.10	EI	Santoro, 1973	LLK
10.77 ± 0.30	EI	Bafus, Gallegos, et al., 1966	RDSH
10.90	PE	Chattorpadhyay, Findley, et al., 1981	Vertical value; LLK
10.82	PE	Cowley, Lattman, et al., 1977	Vertical value; LLK
10.81	PE	Vovna, Lopatin, et al., 1975	Vertical value; LLK

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
CHO⁺	17.3 ± 0.4	?	EI	Bafus, Gallegos, et al., 1966	RDSH
CH₃⁺	17.90 ± 0.40	?	EI	Santoro, 1973	LLK
CH₃⁺	18.6 ± 0.3	?	EI	Bafus, Gallegos, et al., 1966	RDSH
CH₃O⁺	17.3 ± 0.4	?	EI	Bafus, Gallegos, et al., 1966	RDSH
CH₄O₂P⁺	14.90 ± 0.20	2HCHO+H	EI	Santoro, 1973	LLK
CH₄O₂P⁺	15.1 ± 0.2	?	EI	Bafus, Gallegos, et al., 1966	RDSH
CH₄O₃P⁺	13.90 ± 0.20	HCHO+CH₃	EI	Santoro, 1973	LLK
CH₄O₃P⁺	14.4 ± 0.3	?	EI	Bafus, Gallegos, et al., 1966	RDSH
CH₅O₂P⁺	12.91 ± 0.10	2HCHO	EI	Santoro, 1973	LLK
CH₅O₂P⁺	13.9 ± 0.4	?	EI	Bafus, Gallegos, et al., 1966	RDSH
C₂H₅O⁺	14.0 ± 0.2	?	EI	Bafus, Gallegos, et al., 1966	RDSH
C₂H₆O₃P⁺	14.1 ± 0.20	HCHO+H	EI	Santoro, 1973	LLK
C₂H₆O₃P⁺	14.1	?	EI	Bafus, Gallegos, et al., 1966	RDSH
C₂H₇O₃P⁺	11.62 ± 0.10	HCHO	EI	Santoro, 1973	LLK
C₂H₇O₃P⁺	11.9 ± 0.2	CH₂O	EI	Bafus, Gallegos, et al., 1966	RDSH
C₃H₈O₄P⁺	12.73 ± 0.20	H	EI	Santoro, 1973	LLK
PH₂O₂⁺	15.1 ± 0.3	?	EI	Bafus, Gallegos, et al., 1966	RDSH
OP⁺	18.90 ± 0.50	O+CH₃O⁺²H	EI	Santoro, 1973	LLK
PO⁺	19.6 ± 0.3	?	EI	Bafus, Gallegos, et al., 1966	RDSH

References

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

Panneerselvam, Antony, et al., 2007
Panneerselvam, K.; Antony, M.P.; Srinivasan, T.G.; Rao, P.R. Vasudeva, Measurement of enthalpies of vaporization of trialkyl phosphates using correlation gas chromatography, Thermochimica Acta, 2007, 466, 1-2, 49-56, https://doi.org/10.1016/j.tca.2007.10.007 . [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]

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]

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]

Chattorpadhyay, Findley, et al., 1981
Chattorpadhyay, S.; Findley, G.L.; McGlynn, S.P., Photoelectron spectroscopy of phosphites and phosphates, J. Electron Spectrosc. Relat. Phenom., 1981, 24, 27. [all data]

Hodges, McDonnell, et al., 1980
Hodges, R.V.; McDonnell, T.J.; Beauchamp, J.L., Properties reactions of trimethyl phosphite, trimethyl phosphate, triethyl phosphate, and trimethyl phosphorothionate by ion cyclotron resonance spectroscopy, J. Am. Chem. Soc., 1980, 102, 1327. [all data]

Santoro, 1973
Santoro, E., The fragmentation of some alkyl thiophosphate esters by electron-impact, Org. Mass Spectrom., 1973, 7, 589. [all data]

Bafus, Gallegos, et al., 1966
Bafus, D.A.; Gallegos, E.J.; Kiser, R.W., An electron impact investigation of some alkyl phosphate esters, J. Phys. Chem., 1966, 70, 2614. [all data]

Cowley, Lattman, et al., 1977
Cowley, A.H.; Lattman, M.; Montag, R.A.; Verkade, J.G., The coordination behavior of acyclic phosphites; a UV photoelectron spectroscopic study, Inorg. Chim. Acta, 1977, 25, 151. [all data]

Vovna, Lopatin, et al., 1975
Vovna, V.I.; Lopatin, S.N.; Pettsol'd, R.; Vilesov, F.I., Photoelectron spectra and electronic structure of some phosphoryl compounds, Khim. Vys. Energ., 1975, 9, 9. [all data]

Notes

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Symbols used in this document:

AE Appearance energy

Δ_vapH Enthalpy of vaporization

Δ_vapH° Enthalpy of vaporization at standard conditions
Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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AE	Appearance energy
Δ_vapH	Enthalpy of vaporization
Δ_vapH°	Enthalpy of vaporization at standard conditions