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
The 3d structure may be viewed using Java or Javascript.
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
Permanent link for this species. Use this link for bookmarking this species for future reference.
Information on this page:
Other data available:
Data at other public NIST sites:
- Gas Phase Kinetics Database
Options:
- Switch to SI units

Phase change data

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

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

Quantity	Value	Units	Method	Reference	Comment
Δ_vapH°	11.4	kcal/mol	CGC	Panneerselvam, Antony, et al., 2007	Based on data from 408. to 438. K.; AC

Enthalpy of vaporization

Δ_vapH (kcal/mol)	Temperature (K)	Method	Reference	Comment
11.7	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 (atm)
T = temperature (K)

View plot Requires a JavaScript / HTML 5 canvas capable browser.

Temperature (K)	A	B	C	Reference	Comment
299. to 465.9	4.96246	2249.287	-12.294	Stull, 1947	Coefficents calculated by NIST from author's data.

Gas phase ion energetics data

Go To: Top, Phase change data, References, Notes

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)	212.9	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	205.7	kcal/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

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

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
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_vapH	Enthalpy of vaporization
Δ_vapH°	Enthalpy of vaporization at standard conditions