Phthalimide (C8H5NO2): structure, properties and hazards

Names and identifiers

IUPAC name: isoindole-1,3-dione
Synonyms: isoindole-1,3-dione, Gabriel synthesis, Isoindole-1,3-dione
+ 35 more
1H-Isoindole-1,3(2H)-dione, o-Phthalic imide, Benzoimide, 1,3-Isoindolinedione, 2-Diazoindan-1,3-dione, Phenylimide, Phthalimid, 1,2-Benzenedicarboximide, Ftalimmide, DTXSID3026514, 1J6PQ7YI80, NSC-3108, DTXCID506514, CHEBI:38817, RefChem:6138, 201-603-3, 621-254-4, isoindoline-1,3-dione, O-Phthalimide, 2,3-dihydro-1H-isoindole-1,3-dione, phtalimide, 1,3-Dihydroisoindole-1,3-dione, NSC 3108, 1,3-Isoindoledione, 1,3-Dihydro-1,3-dioxoisoindole, Epinastine Impurity 17, MFCD00005881, Phthalimid [German], Ftalimmide [Italian], 2H-benzo[c]azoline-1,3-dione, CAS-85-41-6, Phthalic dicarboximide, Phthalimide; Tafenoquine related; SKF-2450, HSDB 5007, EINECS 201-603-3
Molecular formula: C₈H₅NO₂
Empirical formula: C₈H₅NO₂
Molecular weight: 147.13 g/mol
Exact mass: 147.03203
CAS number: 85-41-6
PubChem CID: 6809
Canonical SMILES: C1=CC=C2C(=C1)C(=O)NC2=O
Isomeric SMILES: C1=CC=C2C(=C1)C(=O)NC2=O
InChI: InChI=1S/C8H5NO2/c10-7-5-3-1-2-4-6(5)8(11)9-7/h1-4H,(H,9,10,11)
InChIKey: XKJCHHZQLQNZHY-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: White crystalline leaflets[3]
3 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Phthalimide is a white to light tan powder. Slightly acidic. (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.
– Dry Powder; CBI [2] EPA Chemical Data Reporting (CDR)
–shown White crystalline leaflets [3] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J., Sr (Ed.). Hawley's Condensed Chemical Dictionary. 12th ed. New York, NY: Van Nostrand Rheinhold Co., 1993, p. 913
Melting point: 238 °C (460 °F, NTP 1992)[1]
Boiling point: Reported, but no value passed the checks.
The value and why
Sublimes (NTP, 1992) (could not be read; source [1])
Solubility in water: Water solubility = 360 mg/l[3]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– less than 1 mg/mL at 67.1 °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 Water solubility = 360 mg/l [3] Hazardous Substances Data Bank (HSDB)cites Yalkowsky SH, Dannenfelser RM; Aquasol Database of Aqueous Solubility. Version 5 (1992)
log P: log Kow = 1.15[3]

Value	As written	Source
–	Phthalimide is a white to light tan powder. Slightly acidic. (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.
–	Dry Powder; CBI	[2] EPA Chemical Data Reporting (CDR)
–shown	White crystalline leaflets	[3] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J., Sr (Ed.). Hawley's Condensed Chemical Dictionary. 12th ed. New York, NY: Van Nostrand Rheinhold Co., 1993, p. 913

Value	As written	Source
–	less than 1 mg/mL at 67.1 °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	Water solubility = 360 mg/l	[3] Hazardous Substances Data Bank (HSDB)cites Yalkowsky SH, Dannenfelser RM; Aquasol Database of Aqueous Solubility. Version 5 (1992)

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: 11
Rings: 2
Aromatic rings: 1
Fraction sp³ carbons (Fsp3): 0
H-bond donors: 1
H-bond acceptors: 2
Rotatable bonds: 0
TPSA (Å²): 46.2
Formal charge: 0
XLogP3: 1.1 PubChem
Complexity: 190 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: C2v of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C65.31%
H3.43%
N9.52%
O21.75%

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: 0.57 Crippen (Wildman and Crippen 1999)
log S (water solubility): -1.52 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 1.78 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 147.13
log P ≤ 5 (Crippen): 0.57
H-bond donors ≤ 5: 1
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 98.2% (111 of 113) of all reports.[4]

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. If symptoms (such as redness or irritation) develop, immediately transport the victim to a hospital. Skin: Immediately flood affected skin with water while removing and isolating all contaminated clothing.[1]

Safety data sheets on the supplier’s page: CATO Research Chemicals Inc., abcr GmbH, Mcule.

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]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
[2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
[3]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[4]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[5]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[6]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[7]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[8]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[9]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[10]MassBank Europe · 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.

Similar structures

Ninhydrin 45%

Tanimoto similarity on Morgan fingerprints (radius 2) with RDKit 2026.09, at least 45%.