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Tryptophan

Athanor · official

C11H12N2O2 · 204.22 g/mol

IUPAC name: (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid

Also called L-tryptophan

Amino acids
Open in Athanor
The structure of Tryptophan
Drawn from its SMILES with RDKit

Names and identifiers

IUPAC name
(2S)-2-amino-3-(1H-indol-3-yl)propanoic acid
Synonyms
L-tryptophan, L-Tryptophane, Tryptophane
+ 35 more

(S)-Tryptophan, trofan, tryptacin, (2S)-2-amino-3-(1H-indol-3-yl)propanoic acid, Ardeytropin, Pacitron, Indole-3-alanine, L-Tryptofan, L-Trp, L-(-)-Tryptophan, L-beta-3-Indolylalanine, 3-Indol-3-ylalanine, triptofano, (-)-Tryptophan, 1-beta-3-Indolylalanine, Tryptophan, L-, 1H-Indole-3-alanine, Tryptophanum, 1beta-3-Indolylalanine, 2-Amino-3-indolylpropanoic acid, Tryptophanum [Latin], (L)-TRYPTOPHAN, (S)-alpha-Amino-1H-indole-3-propanoic acid, alpha'-Amino-3-indolepropionic acid, L-alpha-Aminoindole-3-propionic acid, (S)-alpha-Aminoindole-3-propionic acid, L-alpha-amino-3-indolepropionic acid, EH 121, Alanine, 3-indol-3-yl-, Trytophan-, L-Alanine, 3-(1H-indol-3-yl)-, 1H-Indole-3-alanine, (S)-, NCI-C01729, AI3-18478, Indole-3-propionic acid, alpha-amino-

Molecular formula
C11H12N2O2
Empirical formula
C11H12N2O2
Molecular weight
204.22 g/mol
Exact mass
204.08988
CAS number
73-22-3
PubChem CID
6305
Canonical SMILES
C1=CC=C2C(=C1)C(=CN2)CC(C(=O)O)N
Isomeric SMILES
C1=CC=C2C(=C1)C(=CN2)C[C@@H](C(=O)O)N
InChI
InChI=1S/C11H12N2O2/c12-9(11(14)15)5-7-6-13-10-4-2-1-3-8(7)10/h1-4,6,9,13H,5,12H2,(H,14,15)/t9-/m0/s1
InChIKey
QIVBCDIJIAJPQS-VIFPVBQESA-N
Molfile

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

Physical properties

TemperaturePressureDensity
Appearance
White to slightly yellowish-white ... crystals or crystalline powder[2]
2 values

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

ValueAs writtenSource
–L-tryptophan is a white powder with a flat taste. An essential amino acid; occurs in isomeric forms. (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.
–shownWhite to slightly yellowish-white ... crystals or crystalline powder[2] Hazardous Substances Data Bank (HSDB)cites Reynolds, J.E.F., Prasad, A.B. (eds.) Martindale-The Extra Pharmacopoeia. 28th ed. London: The Pharmaceutical Press, 1982., p. 61
Odor
Odorless[2]
Melting point
290 to 292 °C (554 to 558 °F) (Decomposes) (NTP, 1992)[1]
Solubility in water
Soluble 1 in 100 of water; very slightly soluble in alcohol; practically insoluble chloroform and ether; soluble in hot alcohol and solutions of dilute acids and alkali hydroxides.[2]
2 values

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

ValueAs writtenSource
–1 to 5 mg/mL at 68 °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.
–shownSoluble 1 in 100 of water; very slightly soluble in alcohol; practically insoluble chloroform and ether; soluble in hot alcohol and solutions of dilute acids and alkali hydroxides.[2] Hazardous Substances Data Bank (HSDB)cites Reynolds, J.E.F., Prasad, A.B. (eds.) Martindale-The Extra Pharmacopoeia. 28th ed. London: The Pharmaceutical Press, 1982., p. 61
log P
log Kow = -1.06[2]

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
15
Rings
2
Aromatic rings
2
Fraction sp³ carbons (Fsp3)
0.18
H-bond donors
3
H-bond acceptors
2 computed here · PubChem 3
Rotatable bonds
3
TPSA (Ų)
79.1
Formal charge
0
XLogP3
-1.1 PubChem
Complexity
245 PubChem
Stereocenters
1 definedCIP: C2: S
Double-bond geometry
None specified
Point group
C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C64.69%
  • H5.92%
  • N13.72%
  • O15.67%

Isotope pattern

100%204.09013%205.0931.2%206.095

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
1.12 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-2.06 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: 204.23
  • log P ≤ 5 (Crippen): 1.12
  • H-bond donors ≤ 5: 3
  • H-bond acceptors ≤ 10: 2

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

This chemical does not meet GHS hazard criteria for 98.7% (222 of 225) of all reports.[3]

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]

Storage

  • Protect from light[2]

Safety data sheets on the supplier’s page: PharmaBlock, Sigma-Aldrich, Biorbyt.

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]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
  3. [3]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  4. [4]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  5. [5]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  6. [6]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
  7. [7]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  8. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  9. ·Literature on PubChem

Data last updated 2026-10-14.