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 Copy

  
• IUPAC Standard InChIKey: RYYVLZVUVIJVGH-UHFFFAOYSA-N Copy
• 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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• Information on this page:
  • Condensed phase thermochemistry data
  • Phase change data
  • Gas phase ion energetics data
  • IR Spectrum
  • THz IR spectrum
  • References
  • Notes
• Other data available:
  • Mass spectrum (electron ionization)
  • UV/Visible spectrum
  • Gas Chromatography
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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

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

Enthalpy of vaporization

Enthalpy of sublimation

Enthalpy of fusion

Enthalpy of phase transition

Entropy of phase transition

Gas phase ion energetics data

Go To: Top, Condensed phase thermochemistry data, Phase change data, IR Spectrum, THz IR spectrum, 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

IR Spectrum

Go To: Top, Condensed phase thermochemistry data, Phase change data, Gas phase ion energetics data, THz IR spectrum, References, Notes

Data compiled by: Timothy J. Johnson, Tanya L. Myers, Yin-Fong Su, Russell G. Tonkyn, Molly Rose K. Kelly-Gorham, and Tyler O. Danby

• solid; Bruker Tensor 37 FTIR; 0.96450084 cm^-1 resolution

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

• gas

THz IR spectrum

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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: Edwin J. Heilweil and Matthew B. Campbell

Condensed Phase Spectrum

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Additional Data

References

Go To: Top, Condensed phase thermochemistry data, Phase change data, Gas phase ion energetics data, IR Spectrum, THz IR spectrum, 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, IR Spectrum, THz IR spectrum, 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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