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Caffeine

Athanor · official

C8H10N4O2 · 194.19 g/mol

IUPAC name: 1,3,7-trimethylpurine-2,6-dione

Also called guaranine, theine, trimethylxanthine, 1,3,7-trimethylxanthine

DrugsNatural productsRings
Open in Athanor
The structure of Caffeine
Drawn from its SMILES with RDKit
Harmful or irritantWarningHarmful if swallowed

Names and identifiers

IUPAC name
1,3,7-trimethylpurine-2,6-dione
Synonyms
guaranine, theine, trimethylxanthine
+ 39 more

1,3,7-trimethylxanthine, Guaranine, 1,3,7-Trimethylxanthine, Methyltheobromine, Theine, Thein, Cafeina, Caffein, Cafipel, Koffein, Mateina, Alert-pep, Coffeine, Anhydrous caffeine, Refresh'n, Caffedrine, Vivarin, Stim, No-Doz, Cafamil, Cafecon, Caffine, Dexitac, Nodaca, 7-Methyltheophylline, Eldiatric C, Durvitan, Hycomine, Organex, Nix Nap, Methyltheobromide, Coffeinum, Coffein, 3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione, Tirend, 1,3,7-Trimethylpurine-2,6-dione, 1,3,7-Trimethyl-2,6-dioxopurine, Tri-Aqua, Kofein

Molecular formula
C8H10N4O2
Empirical formula
C4H5N2O
Molecular weight
194.19 g/mol
Exact mass
194.08038
CAS number
58-08-2
PubChem CID
2519
Canonical SMILES
CN1C=NC2=C1C(=O)N(C(=O)N2C)C
Isomeric SMILES
CN1C=NC2=C1C(=O)N(C(=O)N2C)C
InChI
InChI=1S/C8H10N4O2/c1-10-4-9-6-5(10)7(13)12(3)8(14)11(6)2/h4H,1-3H3
InChIKey
RYYVLZVUVIJVGH-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity
Appearance
White, prismatic crystals[3]
4 values

From Hazardous Substances Data Bank (HSDB), the most authoritative source here.

ValueAs writtenSource
–Caffeine appears as odorless white powder or white glistening needles, usually melted together. Bitter taste. Solutions in water are neutral to litmus. Odorless. (NTP, 1992)[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–ODOURLESS WHITE CRYSTALS OR CRYSTALLINE POWDER.[2] ILO-WHO International Chemical Safety Cards (ICSCs)
–shownWhite, prismatic crystals[3] Hazardous Substances Data Bank (HSDB)cites International Labour Office. Encyclopedia of Occupational Health and Safety. Vols. I&II. Geneva, Switzerland: International Labour Office, 1983., p. 118
–White, fleecy masses or long, flexible, silky crystals[3] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 212
Melting point
Reported, but no value passed the checks.
The 2 values and why
  • 460 °F (NTP, 1992) (melting point at or above the boiling point; source [1])
  • 235 °C (melting point at or above the boiling point; source [2])
Boiling point
Reported, but no value passed the checks.
The 2 values and why
  • 352 °F at 760 mmHg (sublimes) (NTP, 1992) (boiling point at or below the melting point; source [1])
  • 178 °C (sublimes) (boiling point at or below the melting point; source [2])
Density
1.23 g/cm³[2]
2 values

2 of 2 sources agree on it (most common value).

ValueAs writtenSource
–1.23 at 64 °F (NTP, 1992) - Denser than water[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–shown1.23 g/cm³[2] ILO-WHO International Chemical Safety Cards (ICSCs)
Solubility in water
Solubility in water, g/100ml: 2.17[2]
3 values

From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.

ValueAs writtenSource
–10 to 50 mg/mL at 73 °F (NTP, 1992)[1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina.
–In water, 2.16X10+4 mg/L at 25 °C[3] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 506
–shownSolubility in water, g/100ml: 2.17[2] ILO-WHO International Chemical Safety Cards (ICSCs)
log P
-0.07[2]
2 values

2 of 2 sources agree on it (most common value).

ValueAs writtenSource
–log Kow = -0.07[3] Hazardous Substances Data Bank (HSDB)cites Hansch, C., Leo, A., D. Hoekman. Exploring QSAR - Hydrophobic, Electronic, and Steric Constants. Washington, DC: American Chemical Society., 1995., p. 44
–shown-0.07[2] ILO-WHO International Chemical Safety Cards (ICSCs)
pKa
pKa = 14.0 at 25 °C[3]
2 values

Only one source reports it.

ValueAs writtenSource
–shownpKa = 14.0 at 25 °C[3] Hazardous Substances Data Bank (HSDB)cites Sigma-Aldrich; Product Search Caffeine (58-08-2). Available from, as of Jan 10, 2014: https://www.sigmaaldrich.com/united-states.html
–pKa = 0.7 (caffeine cation)[3] Hazardous Substances Data Bank (HSDB)cites Svorc L; Int J Electrochem Sci 8: 5755-5773 (2013)
Vapor pressure
9.0 × 10⁻⁷ mmHg at 25 °C (extrapolated)[3]

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms
14
Rings
2
Aromatic rings
2
Fraction sp³ carbons (Fsp3)
0.38
H-bond donors
0
H-bond acceptors
3
Rotatable bonds
0
TPSA (Ų)
61.8 computed here · PubChem 58.4
Formal charge
0
XLogP3
-0.1 PubChem
Complexity
293 PubChem
Stereocenters
None
Double-bond geometry
None specified
Point group
Cs of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C49.48%
  • H5.19%
  • N28.85%
  • O16.48%

Isotope pattern

100%194.08010%195.083196.085

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
-1.03 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-0.87 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
2.3 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 194.19
  • log P ≤ 5 (Crippen): -1.03
  • H-bond donors ≤ 5: 0
  • H-bond acceptors ≤ 10: 3

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Warning

Harmonized EU classification (CLP Annex VI). Source [4].

  • Harmful or irritant
  • H302Harmful if swallowed

Precautionary statements: P264, P270, P301+P317, P330, P501

View all classifications (3)
  • [4] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · WarningH302
  • [5] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 0.6% (13 of 2217) of reports.
  • [5] European Chemicals Agency (ECHA) · 2,217 reports · WarningH302

First aid

  • Eyes: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. Immediately transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. Skin: Immediately flood affected skin with water while removing and isolating all contaminated clothing.[1]
  • Fresh air, rest. Refer for medical attention.[2]
  • Remove contaminated clothes. Rinse skin with plenty of water or shower.[2]
  • First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.[2]

Storage

  • Separated from food and feedstuffs. Well closed.[2]
  • Commercially available caffeine and sodium benzoate and caffeine citrate injection and oral solution should be stored at 15-30 °C. (caffeine and sodium benzoate; Caffeine citrate)[3]

Safety data sheets on the supplier’s page: Sigma-Aldrich, LGC Standards, CATO Research Chemicals Inc..

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. [1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
  2. [2]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  3. [3]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
  4. [4]Regulation (EC) No 1272/2008 of the European Parliament and of the Council · EU reuse policy, CC BY 4.0 · via PubChem · retrieved 2026-10-14
  5. [5]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  6. [6]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
  7. [7]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  8. [8]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  9. [9]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
  10. [10]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  11. [11]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
  12. [12]RRUFF Project · Linked only · via PubChem · retrieved 2026-10-14
  13. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  14. ·Literature on PubChem

Data last updated 2026-10-14.