Ninhydrin

Athanor · official

C₉H₆O₄ · 178.14 g/mol

IUPAC name: 2,2-dihydroxyindene-1,3-dione

Also called triketohydrindene hydrate, amino acid stain, fingerprint reagent, TLC stain

Reagents Rings

Open in Athanor

Drawn from its SMILES with RDKit

Names and identifiers

IUPAC name: 2,2-dihydroxyindene-1,3-dione
Synonyms: triketohydrindene hydrate, amino acid stain, fingerprint reagent
+ 39 more
TLC stain, Ninhydrin hydrate, 1,2,3-Indantrione monohydrate, 2,2-Dihydroxy-1H-indene-1,3(2H)-dione, 1H-Indene-1,3(2H)-dione, 2,2-dihydroxy-, Triketohydrindene hydrate, 2,2-Dihydroxy-1,3-indandione, 2,2-Dihydroxy-1,3-indanedione, 1,2,3-Indantrione, 2-hydrate, DTXSID7025716, 1,3-Indandione, 2,2-dihydroxy-, HCL6S9K23A, DTXCID605716, CHEBI:86374, Indantrione Monohydrate, Monohydrate, Indantrione, RefChem:854157, 207-618-1, Ninhydrine, 2,2-Dihydroxyindane-1,3-dione, 2,2-dihydroxyindene-1,3-dione, Ninhydrin Spray, 2,2-dihydroxy-2,3-dihydro-1H-indene-1,3-dione, Trioxohydrindene monohydrate, MFCD00003791, 2,2-Dihydroxy-1,3-dioxoindan, CHEMBL1221925, CCRIS 4849, EINECS 207-618-1, UNII-HCL6S9K23A, BRN 1910963, 2,2-dihydroxy-2-hydrocyclopenta[1,2-a]benzene-1,3-dione, Ningidrin, nin-hydrin, AI3-04464, Ninhydrin, solution, Ninhydrin ACS grade, Ninhydrin solution R1, Ninhydrin solution R2
Molecular formula: C₉H₆O₄
Empirical formula: C₉H₆O₄
Molecular weight: 178.14 g/mol
Exact mass: 178.02661
CAS number: 485-47-2
PubChem CID: 10236
Canonical SMILES: C1=CC=C2C(=C1)C(=O)C(C2=O)(O)O
Isomeric SMILES: C1=CC=C2C(=C1)C(=O)C(C2=O)(O)O
InChI: InChI=1S/C9H6O4/c10-7-5-3-1-2-4-6(5)8(11)9(7,12)13/h1-4,12-13H
InChIKey: FEMOMIGRRWSMCU-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Ninhydrin appears as white to light yellow crystals or powder. Becomes anhydrous with reddening at 125-130 °C (257-266 °F). (NTP, 1992)[1]
2 values
From CAMEO Chemicals, the most authoritative source here.
Value As written Source
–shown Ninhydrin appears as white to light yellow crystals or powder. Becomes anhydrous with reddening at 257-266 °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.
– ODOURLESS COLOURLESS-TO-CREAM-COLOURED CRYSTALLINE SOLID. [2] ILO-WHO International Chemical Safety Cards (ICSCs)
Melting point: 241 to 243 °C (466 to 469 °F) (Decomposes) (NTP, 1992)[1]
Density: 0.862 @25 °C[3]
Solubility in water: Solubility in water: soluble[2]
2 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– 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.
–shown Solubility in water: soluble [2] ILO-WHO International Chemical Safety Cards (ICSCs)
Vapor pressure: 0.000000236 [mmHg] @25 °C[3]

Value	As written	Source
–shown	Ninhydrin appears as white to light yellow crystals or powder. Becomes anhydrous with reddening at 257-266 °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.
–	ODOURLESS COLOURLESS-TO-CREAM-COLOURED CRYSTALLINE SOLID.	[2] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	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.
–shown	Solubility in water: soluble	[2] ILO-WHO International Chemical Safety Cards (ICSCs)

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: 13
Rings: 2
Aromatic rings: 1
Fraction sp³ carbons (Fsp3): 0.11
H-bond donors: 2
H-bond acceptors: 4
Rotatable bonds: 0
TPSA (Å²): 74.6
Formal charge: 0
XLogP3: 0.1 PubChem
Complexity: 243 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: C2 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C60.68%
H3.40%
O35.92%

Isotope pattern

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: -0.25 Crippen (Wildman and Crippen 1999)
log S (water solubility): -1.13 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.45 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 178.14
log P ≤ 5 (Crippen): -0.25
H-bond donors ≤ 5: 2
H-bond acceptors ≤ 10: 4

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

No GHS hazard classification was found in the sources.

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.[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]

Safety data sheets on the supplier’s page: eNovation Chemicals, abcr GmbH, BLD Pharm.

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

Spectra

NMRNMRShiftDB
1H NMRSpectraBase (Varian A-60)
13C NMRSpectraBase
17O NMRSpectraBase
GC-MSNIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · SpectraBase
FTIRSpectraBase (KBr WAFER)
ATR-IRSpectraBase (Bruker Tensor 27 FT-IR · ATR-Neat (DuraSamplIR II))
RamanSpectraBase (Bruker MultiRAM Stand Alone FT-Raman Spectrometer · FT-Raman)

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]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
[2]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[3]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[4]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[5]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[6]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
·Literature on PubChem

Data last updated 2026-10-14.