N-Methylpyrrolidone

Athanor · official

C₅H₉NO · 99.13 g/mol

IUPAC name: 1-methylpyrrolidin-2-one

Also called NMP, 1-methyl-2-pyrrolidinone

Solvents Rings

Open in Athanor

Drawn from its SMILES with RDKit

DangerCauses skin irritation · Causes serious eye irritation · May cause respiratory irritation

Names and identifiers

IUPAC name: 1-methylpyrrolidin-2-one
Synonyms: NMP, 1-methyl-2-pyrrolidinone, 1-METHYL-2-PYRROLIDINONE
+ 35 more
N-Methyl-2-pyrrolidone, N-Methyl-2-pyrrolidinone, Methylpyrrolidone, 1-Methyl-2-pyrrolidone, 1-Methylpyrrolidone, Methyl pyrrolidone, N-Methylpyrrolidinone, 1-Methylpyrrolidinone, n-methyl-pyrrolidone, 1-Methyl-5-pyrrolidinone, 2-Pyrrolidinone, 1-methyl-, 1-Methylazacyclopentan-2-one, N-Methyl-gamma-butyrolactam, Agsolex 1, DTXSID6020856, N-Methyl-alpha-pyrrolidone, Microposit 2001, N-Methyl-alpha-pyrrolidinone, NSC-4594, JR9CE63FPM, DTXCID60856, CHEBI:7307, NSC4594, N 0131, RefChem:57504, DTXSID101057601, 212-828-1, 1-methylpyrrolidin-2-one, M-Pyrol, N-methylpyrrolidin-2-one, 1-methyl-2-pyrrolidon, N-methyl pyrrolidone, 1-methylpyrrolidine-2-one, N-methyl pyrrolidinone, Methyl-2-pyrrolidinone
Molecular formula: C₅H₉NO
Empirical formula: C₅H₉NO
Molecular weight: 99.13 g/mol
Exact mass: 99.06841
CAS number: 872-50-4
PubChem CID: 13387
Canonical SMILES: CN1CCCC1=O
Isomeric SMILES: CN1CCCC1=O
InChI: InChI=1S/C5H9NO/c1-6-4-2-3-5(6)7/h2-4H2,1H3
InChIKey: SECXISVLQFMRJM-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: N-methyl-2-pyrrolidone appears as a clear colorless liquid with a "fishlike" odor. Denser than water. Flash point 93 °C (199 °F). Contact may irritate skin, eyes and mucous membranes. May be toxic by ingestion.[1]
4 values
From CAMEO Chemicals, the most authoritative source here.
Value As written Source
–shown N-methyl-2-pyrrolidone appears as a clear colorless liquid with a "fishlike" odor. Denser than water. Flash point 199 °F. Contact may irritate skin, eyes and mucous membranes. May be toxic by ingestion. [1] CAMEO Chemicals
– Liquid; Liquid; Other Solid; Dry Powder; CBI [2] EPA Chemical Data Reporting (CDR)
– COLOURLESS HYGROSCOPIC LIQUID WITH CHARACTERISTIC ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– A clear colorless liquid with a fish-like odor. [4] Occupational Safety and Health Administration (OSHA)
Odor: Mild amine odor[5]
Melting point: -23.09 °C[6]
5 values
4 of 5 sources agree on it (most common value).
Value As written Source
−23 °C -9 °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.
−25 °C -25 °C [5] Hazardous Substances Data Bank (HSDB)cites Ashford, R.D. Ashford's Dictionary of Industrial Chemicals. London, England: Wavelength Publications Ltd., 1994., p. 595
−24.4 °C -24.4 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−23 °C -9 °F [4] Occupational Safety and Health Administration (OSHA)
−23.1 °Cshown -23.09 °C [6] PAC Chemical Database, U.S. Department of Energy
Boiling point: 202 °C[3]
4 values
4 of 4 sources agree on it (most common value).
Value As written Source
202 °C 396 °F at 760 mmHg (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.
202 °Cshown 202 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
202 °C 396 °F [4] Occupational Safety and Health Administration (OSHA)
202 °C 202 °C @760 [mm Hg] [6] PAC Chemical Database, U.S. Department of Energy
Density: 1.027 @25 °C[6]
4 values
4 of 4 sources agree on it (most common value).
Value As written Source
– 1.03 at 77 °F (USCG, 1999) - Denser than water [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
– Relative density (water = 1): 1.03 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 1.03 [4] Occupational Safety and Health Administration (OSHA)
–shown 1.027 @25 °C [6] PAC Chemical Database, U.S. Department of Energy
Solubility in water: Solubility in water: miscible[3]
5 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– greater than or equal to 100 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.
– Miscible with castor oil [5] 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. 842
– Miscible with lower alcohols and ketones [5] Hazardous Substances Data Bank (HSDB)cites Kirk-Othmer Encyclopedia of Chemical Technology. 4th ed. Volumes 1: New York, NY. John Wiley and Sons, 1991-Present., p. V20: 714 (1996)
– Moderately soluble in aliphatic hydrocarbons and dissolves many organic and inorganic compounds. [5] Hazardous Substances Data Bank (HSDB)cites Kirk-Othmer Encyclopedia of Chemical Technology. 4th ed. Volumes 1: New York, NY. John Wiley and Sons, 1991-Present., p. V20: 714 (1996)
–shown Solubility in water: miscible [3] ILO-WHO International Chemical Safety Cards (ICSCs)
log P: -0.38[3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
– log Kow = -0.38 [5] Hazardous Substances Data Bank (HSDB)cites Sasaki H et al; Int J Pharm 44: 15-24 (1988)
–shown -0.38 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Vapor pressure: 3.45 × 10⁻¹ mmHg at 25 °C[5]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source
0.345 mmHgshown 3.45X10-1 mm Hg at 25 °C [5] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
0.29 mmHg Vapor pressure, Pa at 25 °C: 39 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
0.345 mmHg 0.345 [mm Hg] @25 °C [6] PAC Chemical Database, U.S. Department of Energy
Flash point: 96 °C (204 °F) (OPEN CUP)[5]
4 values
3 of 4 sources agree on it (most common value).
Value As written Source
96 °C 204 °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.
96 °Cshown 204 °F (96 °C) (OPEN CUP) [5] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-89
86 °C 86 °C c.c. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
96 °C 204 °F [4] Occupational Safety and Health Administration (OSHA)
Autoignition temperature: 245 °C[3]
2 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
346 °C 655 °F (346 °C) [5] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-89
245 °Cshown 245 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Viscosity: Reported, but no value passed the checks.
The value and why
1.62 mm²/s at 25 °C (could not be read; source [3])

Value	As written	Source
–shown	N-methyl-2-pyrrolidone appears as a clear colorless liquid with a "fishlike" odor. Denser than water. Flash point 199 °F. Contact may irritate skin, eyes and mucous membranes. May be toxic by ingestion.	[1] CAMEO Chemicals
–	Liquid; Liquid; Other Solid; Dry Powder; CBI	[2] EPA Chemical Data Reporting (CDR)
–	COLOURLESS HYGROSCOPIC LIQUID WITH CHARACTERISTIC ODOUR.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	A clear colorless liquid with a fish-like odor.	[4] Occupational Safety and Health Administration (OSHA)

Value	As written	Source
−23 °C	-9 °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.
−25 °C	-25 °C	[5] Hazardous Substances Data Bank (HSDB)cites Ashford, R.D. Ashford's Dictionary of Industrial Chemicals. London, England: Wavelength Publications Ltd., 1994., p. 595
−24.4 °C	-24.4 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−23 °C	-9 °F	[4] Occupational Safety and Health Administration (OSHA)
−23.1 °Cshown	-23.09 °C	[6] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
202 °C	396 °F at 760 mmHg (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.
202 °Cshown	202 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
202 °C	396 °F	[4] Occupational Safety and Health Administration (OSHA)
202 °C	202 °C @760 [mm Hg]	[6] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	1.03 at 77 °F (USCG, 1999) - Denser than water	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
–	Relative density (water = 1): 1.03	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	1.03	[4] Occupational Safety and Health Administration (OSHA)
–shown	1.027 @25 °C	[6] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	greater than or equal to 100 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.
–	Miscible with castor oil	[5] 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. 842
–	Miscible with lower alcohols and ketones	[5] Hazardous Substances Data Bank (HSDB)cites Kirk-Othmer Encyclopedia of Chemical Technology. 4th ed. Volumes 1: New York, NY. John Wiley and Sons, 1991-Present., p. V20: 714 (1996)
–	Moderately soluble in aliphatic hydrocarbons and dissolves many organic and inorganic compounds.	[5] Hazardous Substances Data Bank (HSDB)cites Kirk-Othmer Encyclopedia of Chemical Technology. 4th ed. Volumes 1: New York, NY. John Wiley and Sons, 1991-Present., p. V20: 714 (1996)
–shown	Solubility in water: miscible	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	log Kow = -0.38	[5] Hazardous Substances Data Bank (HSDB)cites Sasaki H et al; Int J Pharm 44: 15-24 (1988)
–shown	-0.38	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
0.345 mmHgshown	3.45X10-1 mm Hg at 25 °C	[5] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
0.29 mmHg	Vapor pressure, Pa at 25 °C: 39	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
0.345 mmHg	0.345 [mm Hg] @25 °C	[6] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
96 °C	204 °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.
96 °Cshown	204 °F (96 °C) (OPEN CUP)	[5] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-89
86 °C	86 °C c.c.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
96 °C	204 °F	[4] Occupational Safety and Health Administration (OSHA)

Value	As written	Source
346 °C	655 °F (346 °C)	[5] Hazardous Substances Data Bank (HSDB)cites National Fire Protection Association; Fire Protection Guide to Hazardous Materials. 14TH Edition, Quincy, MA 2010, p. 325-89
245 °Cshown	245 °C	[3] 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: 7
Rings: 1
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0.8
H-bond donors: 0
H-bond acceptors: 1
Rotatable bonds: 0
TPSA (Å²): 20.3
Formal charge: 0
XLogP3: -0.5 PubChem
Complexity: 90 PubChem
Stereocenters: None
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

C60.58%
H9.15%
N14.13%
O16.14%

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: 0.24 Crippen (Wildman and Crippen 1999)
log S (water solubility): -0.6 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.13 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 99.13
log P ≤ 5 (Crippen): 0.24
H-bond donors ≤ 5: 0
H-bond acceptors ≤ 10: 1

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

Danger

Harmonized EU classification (CLP Annex VI). Source [7].

Harmful or irritant
Health hazard

NFPA 704[5]

H315Causes skin irritation
H319Causes serious eye irritation
H335May cause respiratory irritation

Precautionary statements: P203, P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P318, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501

View all classifications (3)

[7] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH315, H319, H335
[8] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for < 0.1% (1 of 2679) of reports.
[8] European Chemicals Agency (ECHA) · 2,679 reports · DangerH335, H360

Exposure limits

EU-OEL: 40 mg/m[3]
MAK (Maximale Arbeitsplatz Konzentration): 82 mg/m[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]
Fresh air, rest. Refer for medical attention.[3]
Rinse skin with plenty of water or shower.[3]
First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.[3]

Storage

Dry. Ventilation along the floor. Separated from strong oxidants, strong acids, strong bases, copper and plastics.[3]
Small quantities can be stored in polyethylene, polypropylene, or clear glass bottles.[5]
Safe Storage: Separated from oxidants, rubber, plastics, aluminum and light metals. Dry. Ventilation along the floor.[5]

Incompatibilities

Reacts with sulfur or carbon disulfide at high temperatures and pressures.[5]
Attacks aluminum, light metals, rubber and plastics.[5]

Safety data sheets on the supplier’s page: Yuhao Chemical, J&H Chemical Co.,ltd, Thermo Fisher Scientific.

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]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[4]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
[5]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[6]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[7]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
[8]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[9]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[10]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[11]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[12]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[13]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.