Caffeine

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Condensed phase thermochemistry data

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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
173.2298.Cesaro and Starec, 1980T = 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.
232.298.15Bothe and Cammenga, 1979 

Phase change data

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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
Tfus509.3KN/ABruns, Reichelt, et al., 1984Crystal phase 1 phase; Uncertainty assigned by TRC = 0.1 K; TRC
Tfus508.KN/AGrady, Hays, et al., 1973Uncertainty assigned by TRC = 1. K; TRC
Quantity Value Units Method Reference Comment
Ttriple508.3KN/AWeinstein, Leffler, et al., 1984Crystal 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 ± 2.4634. to 743.DSCBoller and Wiedemann, 1998AC

Enthalpy of sublimation

ΔsubH (kJ/mol) Temperature (K) Method Reference Comment
103.6423.UVEbeling and Franck, 2010Based on data from 373. to 473. K.; AC
112.6 ± 2.4315. to 364.MEBoller and Wiedemann, 1998AC

Enthalpy of fusion

ΔfusH (kJ/mol) Temperature (K) Method Reference Comment
24.8507.7DSCGuo, Sadiq, et al., 2010AC
19.86509.5DSCDong, Li, et al., 2007AC
21.9510.2DSCPinto and Diogo, 2006AC
19.38510.2DSCKlous, Bronner, et al., 2005AC
18.3510.N/ADomalski and Hearing, 1990See also Ohm and Lippold, 1985.; AC
20.95508.3DSCWeinstein, Leffler, et al., 1984, 2AC

Enthalpy of phase transition

ΔHtrs (kJ/mol) Temperature (K) Initial Phase Final Phase Reference Comment
0.940426.crystaline, IIcrystaline, ICesaro and Starec, 1980to form.; DH
5.600512.crystaline, IliquidCesaro and Starec, 1980to liquid.; DH
0.9632414.crystaline, IIcrystaline, IBothe and Cammenga, 1979Low temperature to a high temperature transition.; DH
5.160509.3crystaline, IliquidBothe and Cammenga, 1979DH

Entropy of phase transition

ΔStrs (J/mol*K) Temperature (K) Initial Phase Final Phase Reference Comment
2.2426.crystaline, IIcrystaline, ICesaro and Starec, 1980to; DH
10.9512.crystaline, IliquidCesaro and Starec, 1980DH
6.83414.crystaline, IIcrystaline, IBothe and Cammenga, 1979Low; DH
10.1509.3crystaline, IliquidBothe and Cammenga, 1979DH

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:


Gas phase ion energetics data

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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
7.95PEDougherty, Younathan, et al., 1978LLK
8.50CTSSlifkin and Allison, 1967RDSH

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

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