Caffeine
- Formula: C8H10N4O2
- Molecular weight: 194.1906
- IUPAC Standard InChI: InChI=1S/C8H10N4O2/c1-10-4-9-6-5(10)7(13)12(3)8(14)11(6)2/h4H,1-3H3
- IUPAC Standard InChIKey: RYYVLZVUVIJVGH-UHFFFAOYSA-N
- CAS Registry Number: 58-08-2
- 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: 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl-; Alert-Pep; Cafeina; Caffein; Caffine; Cafipel; Coffeine; Guaranine; Koffein; Mateina; Methyltheobromine; No-Doz; Refresh'n; Stim; Thein; Theine; 1,3,7-Trimethyl-2,6-dioxopurine; 1,3,7-Trimethylxanthine; Cafamil; Cafecon; Caffeine, synthetic; Eldiatric C; Nix Nap; Nodaca; NCI-C02733; Theobromine, 1-methyl-; Theophylline, 7-methyl; Xanthine, 1,3,7-trimethyl; 3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione; Coffein; Kofein; Organex; Monomethyl derivative of Theophylline; Theobromine Me; Theophylline Me; Caffedrine; Hycomine; NSC 5036; Tri-Aqua; Wigraine; 7-Methylxanthine, N,N'-dimethyl-; 1,3,7-Trimethyl-3,7-dihydro-1H-purine-2,6-dione; A.S.A. and Codeine Compound; Anacin; Anacin Maximum Strength; Bayer Select Headache Pain; Cafergot; DHCplus; Dasin; Fiorinal; Hycomine Compound; Midol Maximum Strength; Norgesic; P-A-C Analgesic Tablets; Phensal; Propoxyphene Compound 65; SK-65 Compound; Synalgos; Synalgos-DC; Vanquish; component of A.S.A. Compound; component of Ansemco 2; component of Dilone; component of Midol; component of P-A-C Compound; component of Percodan; 71701-02-5; 95789-13-2; A.S.A. and Codeine Compound (Salt/Mix); Anacin (Salt/Mix); Anacin Maximum Strength (Salt/Mix); Bayer Select Headache Pain (Salt/Mix); Cafergot (Salt/Mix); DHCplus (Salt/Mix); Dasin (Salt/Mix); Fiorinal (Salt/Mix); Hycomine Compound (Salt/Mix); Midol Maximum Strength (Salt/Mix); Norgesic (Salt/Mix); P-A-C Analgesic Tablets (Salt/Mix); Phensal (Salt/Mix); Propoxyphene Compound 65 (Salt/Mix); SK-65 Compound (Salt/Mix); Synalgos (Salt/Mix); Synalgos-DC (Salt/Mix); Vanquish (Salt/Mix); component of A.S.A. Compound (Salt/Mix); component of Ansemco 2 (Salt/Mix); component of Dilone (Salt/Mix); component of Midol (Salt/Mix); component of P-A-C Compound (Salt/Mix); component of Percodan (Salt/Mix)
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Condensed phase thermochemistry data
Go To: Top, Phase change data, Gas phase ion energetics data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: Eugene S. Domalski and Elizabeth D. Hearing
Constant pressure heat capacity of solid
| Cp,solid (J/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 173.2 | 298. | Cesaro and Starec, 1980 | T = 300 to 392 K. Unsmoothed experimental data and equation given. Cp = 41.4 + 0.104(T-298) cal mol-1 K-1. Data given at 298 K is an extrapolation by the author. |
| 232. | 298.15 | Bothe and Cammenga, 1979 |
Phase change data
Go To: Top, Condensed phase thermochemistry data, Gas phase ion energetics data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
DH - Eugene S. Domalski and Elizabeth D. Hearing
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| Tfus | 509.3 | K | N/A | Bruns, Reichelt, et al., 1984 | Crystal phase 1 phase; Uncertainty assigned by TRC = 0.1 K; TRC |
| Tfus | 508. | K | N/A | Grady, Hays, et al., 1973 | Uncertainty assigned by TRC = 1. K; TRC |
| Quantity | Value | Units | Method | Reference | Comment |
| Ttriple | 508.3 | K | N/A | Weinstein, Leffler, et al., 1984 | Crystal phase 1 phase; Uncertainty assigned by TRC = 1.5 K; DSC; TRC |
Enthalpy of vaporization
| ΔvapH (kJ/mol) | Temperature (K) | Method | Reference | Comment |
|---|---|---|---|---|
| 64.9 ± 2.4 | 634. to 743. | DSC | Boller and Wiedemann, 1998 | AC |
Enthalpy of sublimation
| ΔsubH (kJ/mol) | Temperature (K) | Method | Reference | Comment |
|---|---|---|---|---|
| 103.6 | 423. | UV | Ebeling and Franck, 2010 | Based on data from 373. to 473. K.; AC |
| 112.6 ± 2.4 | 315. to 364. | ME | Boller and Wiedemann, 1998 | AC |
Enthalpy of fusion
| ΔfusH (kJ/mol) | Temperature (K) | Method | Reference | Comment |
|---|---|---|---|---|
| 24.8 | 507.7 | DSC | Guo, Sadiq, et al., 2010 | AC |
| 19.86 | 509.5 | DSC | Dong, Li, et al., 2007 | AC |
| 21.9 | 510.2 | DSC | Pinto and Diogo, 2006 | AC |
| 19.38 | 510.2 | DSC | Klous, Bronner, et al., 2005 | AC |
| 18.3 | 510. | N/A | Domalski and Hearing, 1990 | See also Ohm and Lippold, 1985.; AC |
| 20.95 | 508.3 | DSC | Weinstein, Leffler, et al., 1984, 2 | AC |
Enthalpy of phase transition
| ΔHtrs (kJ/mol) | Temperature (K) | Initial Phase | Final Phase | Reference | Comment |
|---|---|---|---|---|---|
| 0.940 | 426. | crystaline, II | crystaline, I | Cesaro and Starec, 1980 | to form.; DH |
| 5.600 | 512. | crystaline, I | liquid | Cesaro and Starec, 1980 | to liquid.; DH |
| 0.9632 | 414. | crystaline, II | crystaline, I | Bothe and Cammenga, 1979 | Low temperature to a high temperature transition.; DH |
| 5.160 | 509.3 | crystaline, I | liquid | Bothe and Cammenga, 1979 | DH |
Entropy of phase transition
| ΔStrs (J/mol*K) | Temperature (K) | Initial Phase | Final Phase | Reference | Comment |
|---|---|---|---|---|---|
| 2.2 | 426. | crystaline, II | crystaline, I | Cesaro and Starec, 1980 | to; DH |
| 10.9 | 512. | crystaline, I | liquid | Cesaro and Starec, 1980 | DH |
| 6.83 | 414. | crystaline, II | crystaline, I | Bothe and Cammenga, 1979 | Low; DH |
| 10.1 | 509.3 | crystaline, I | liquid | Bothe and Cammenga, 1979 | DH |
Gas phase ion energetics data
Go To: Top, Condensed phase thermochemistry data, Phase change data, References, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
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
Ionization energy determinations
| IE (eV) | Method | Reference | Comment |
|---|---|---|---|
| 7.95 | PE | Dougherty, Younathan, et al., 1978 | LLK |
| 8.50 | CTS | Slifkin and Allison, 1967 | RDSH |
References
Go To: Top, Condensed phase thermochemistry data, Phase change data, Gas phase ion energetics data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Cesaro and Starec, 1980
Cesaro, A.; Starec, G.,
Thermodynamic properties of caffeine crystal forms,
J. Phys. Chem., 1980, 84, 1345-1346. [all data]
Bothe and Cammenga, 1979
Bothe, H.; Cammenga, H.K.,
Phase transitions and thermodynamic properties of anhydrous caffeine,
J. Therm. Anal., 1979, 16, 267-275. [all data]
Bruns, Reichelt, et al., 1984
Bruns, S.; Reichelt, J.; Cammenga, H.K.,
Thermochemical investigation of theophylline, theophylline hydrate and their aqueous solutions,
Thermochim. Acta, 1984, 72, 31. [all data]
Grady, Hays, et al., 1973
Grady, L.T.; Hays, S.E.; King, R.H.; Klein, H.R.; Mader, W.J.; Wyatt, D.K.; Zimmere, R.O.,
Drug purity profiles,
J. Pharm. Sci., 1973, 62, 459. [all data]
Weinstein, Leffler, et al., 1984
Weinstein, D.I.; Leffler, A.J.; Currie, J.A.,
Phase Transitions in Bicyclic Compounds,
Mol. Cryst. Liq. Cryst., 1984, 104, 95. [all data]
Boller and Wiedemann, 1998
Boller, A.; Wiedemann, H.G.,
Journal of Thermal Analysis and Calorimetry, 1998, 53, 2, 431-439, https://doi.org/10.1023/A:1010133106907
. [all data]
Ebeling and Franck, 2010
Ebeling, H.; Franck, E.U.,
Spectroscopic Determination of Caffeine Solubility in Supercritical Carbon Dioxide,
Berichte der Bunsengesellschaft für physikalische Chemie, 2010, 88, 9, 862-865, https://doi.org/10.1002/bbpc.19840880918
. [all data]
Guo, Sadiq, et al., 2010
Guo, Kun; Sadiq, Ghazala; Seaton, Colin; Davey, Roger; Yin, Qiuxiang,
Co-Crystallization in the Caffeine/Maleic Acid System: Lessons from Phase Equilibria,
Crystal Growth & Design, 2010, 10, 1, 268-273, https://doi.org/10.1021/cg900885n
. [all data]
Dong, Li, et al., 2007
Dong, Jia-Xin; Li, Qiang; Tan, Zhi-Cheng; Zhang, Zhi-Heng; Liu, Yi,
The standard molar enthalpy of formation, molar heat capacities, and thermal stability of anhydrous caffeine,
The Journal of Chemical Thermodynamics, 2007, 39, 1, 108-114, https://doi.org/10.1016/j.jct.2006.05.009
. [all data]
Pinto and Diogo, 2006
Pinto, Susana S.; Diogo, Hermínio P.,
Thermochemical study of two anhydrous polymorphs of caffeine,
The Journal of Chemical Thermodynamics, 2006, 38, 12, 1515-1522, https://doi.org/10.1016/j.jct.2006.04.008
. [all data]
Klous, Bronner, et al., 2005
Klous, Marjolein G.; Bronner, Gaby M.; Nuijen, Bastiaan; Ree, Jan M. van; Beijnen, Jos H.,
Pharmaceutical heroin for inhalation: Thermal analysis and recovery experiments after volatilisation,
Journal of Pharmaceutical and Biomedical Analysis, 2005, 39, 5, 944-950, https://doi.org/10.1016/j.jpba.2005.06.011
. [all data]
Domalski and Hearing, 1990
Domalski, Eugene S.; Hearing, Elizabeth D.,
Heat Capacities and Entropies of Organic Compounds in the Condensed Phase Volume II,
J. Phys. Chem. Ref. Data, 1990, 19, 4, 881, https://doi.org/10.1063/1.555876
. [all data]
Ohm and Lippold, 1985
Ohm, A.; Lippold, B.C.,
Surface tension of solid drugs and its correlation with solubility,
Int. J. Pharm. Tech. Prod. Mfg., 1985, 6, 4, 1. [all data]
Weinstein, Leffler, et al., 1984, 2
Weinstein, D.I.; Leffler, A.J.; Currie, J.A.,
Phase Transitions In Bicyclic Compounds,
Molecular Crystals and Liquid Crystals, 1984, 104, 1-2, 95-109, https://doi.org/10.1080/00268948408070401
. [all data]
Dougherty, Younathan, et al., 1978
Dougherty, D.; Younathan, E.S.; Voll, R.; Abdulnur, S.; McGlynn, S.P.,
Photoelectron spectroscopy of some biological molecules,
J. Electron Spectrosc. Relat. Phenom., 1978, 13, 379. [all data]
Slifkin and Allison, 1967
Slifkin, M.A.; Allison, A.C.,
Measurement of ionization potentials from contact charge transfer spectra,
Nature, 1967, 215, 949. [all data]
Notes
Go To: Top, Condensed phase thermochemistry data, Phase change data, Gas phase ion energetics data, References
- Symbols used in this document:
Cp,solid Constant pressure heat capacity of solid Tfus Fusion (melting) point Ttriple Triple point temperature ΔHtrs Enthalpy of phase transition ΔStrs Entropy of phase transition ΔfusH Enthalpy of fusion ΔsubH Enthalpy of sublimation ΔvapH Enthalpy of vaporization - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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