Butyraldehyde (C4H8O): structure, properties and hazards

Names and identifiers

IUPAC name: butanal
Synonyms: butanal, butyral, n-butyraldehyde
+ 35 more
Butyral, 1-butanal, Butyric aldehyde, Butaldehyde, Butanaldehyde, Butal, n-Butanal, Butylaldehyde, Butalyde, Butyraldehyd, Aldeide butirrica, Aldehyde butyrique, Butyrylaldehyde, n-Butyl aldehyde, butan-1-al, NCI-C56291, FEMA Number 2219, DTXSID8021513, NSC-62779, DTXCID601513, FEMA NO. 2219, H21352682A, CHEBI:15743, RefChem:31171, 204-646-6, Butyl aldehyde, NSC 62779, n-C3H7CHO, MFCD00007023, BUTANAL N-BUTYRALDEHYDE, Butyraldehyd [German], 1-butanone, Aldehyde butyrique [French], Aldeide butirrica [Italian], CCRIS 3221
Molecular formula: C₄H₈O
Empirical formula: C₄H₈O
Molecular weight: 72.11 g/mol
Exact mass: 72.05751
CAS number: 123-72-8
PubChem CID: 261
Canonical SMILES: CCCC=O
Isomeric SMILES: CCCC=O
InChI: InChI=1S/C4H8O/c1-2-3-4-5/h4H,2-3H2,1H3
InChIKey: ZTQSAGDEMFDKMZ-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Water-white liquid[4]
4 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Butyraldehyde appears as a clear liquid with a pungent odor. Less dense than water and insoluble in water. Vapors heavier than air. [1] CAMEO Chemicals
– Liquid [2] EPA Chemical Data Reporting (CDR)
– COLOURLESS LIQUID WITH PUNGENT ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown Water-white liquid [4] 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. 206
Odor: Characteristic, pungent, aldehyde odor[4]
Melting point: -99 °C (-146 °F, NTP 1992)[1]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source
−99 °Cshown -146 °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.
−99 °C -99 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−96.9 °C -96.86 °C [5] PAC Chemical Database, U.S. Department of Energy
Boiling point: 74.8 °C[3]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source
75 °C 167 °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.
74.8 °Cshown 74.8 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
74.7 °C 74.7 °C @760 [mm Hg] [5] PAC Chemical Database, U.S. Department of Energy
Density: 0.803 at 20 °C (68 °F) (USCG, 1999) - Less dense than water[1]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
–shown 0.803 at 68 °F (USCG, 1999) - Less dense 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.
– 0.8 g/cm³ [3] ILO-WHO International Chemical Safety Cards (ICSCs)
1 more value was reported but failed the checks (unreadable or out of range), so it is not shown.
Solubility in water: Solubility in water, g/100ml: 7[3]
3 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– less than 1 mg/mL at 66 °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, 7.10X10+4 mg/L at 25 °C [4] Hazardous Substances Data Bank (HSDB)cites Yalkowsky SH, Dannenfelser RM; The AQUASOL dATAbASE of Aqueous Solubility. Fifth ed, Tucson,AZ: Univ Az, College of Pharmacy (1992)
–shown Solubility in water, g/100ml: 7 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
log P: 0.88[3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
– log Kow = 0.88 [4] 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. 9
–shown 0.88 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Vapor pressure: 111 mmHg at 25 °C[4]
4 values
2 of 4 sources agree on it (most common value).
Value As written Source
91.5 mmHg 91.5 mmHg 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.
111 mmHgshown 111 mm Hg at 25 °C [4] 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.
92 mmHg Vapor pressure, kPa at 20 °C: 12.2 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
111 mmHg 111 [mm Hg] @25 °C [5] PAC Chemical Database, U.S. Department of Energy
Flash point: -12 °C c.c.[3]
3 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
−7 °C 20 °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.
−22 °C -8 °F (-22 °C) (CLOSED CUP) [4] Hazardous Substances Data Bank (HSDB)cites Fire Protection Guide to Hazardous Materials. 13 ed. Quincy, MA: National Fire Protection Association, 2002., p. 325-9
−12 °Cshown -12 °C c.c. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Autoignition temperature: 230 °C[3]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source
230 °C 446 °F (USCG, 1999) [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.
218 °C 425 °F 218 °C [4] Hazardous Substances Data Bank (HSDB)cites Fire Protection Guide to Hazardous Materials. 13 ed. Quincy, MA: National Fire Protection Association, 2002., p. 325-27
230 °Cshown 230 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Viscosity: 0.45 cP at 20 °C[4]

Value	As written	Source
–	Butyraldehyde appears as a clear liquid with a pungent odor. Less dense than water and insoluble in water. Vapors heavier than air.	[1] CAMEO Chemicals
–	Liquid	[2] EPA Chemical Data Reporting (CDR)
–	COLOURLESS LIQUID WITH PUNGENT ODOUR.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown	Water-white liquid	[4] 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. 206

Value	As written	Source
−99 °Cshown	-146 °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.
−99 °C	-99 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−96.9 °C	-96.86 °C	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
75 °C	167 °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.
74.8 °Cshown	74.8 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
74.7 °C	74.7 °C @760 [mm Hg]	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–shown	0.803 at 68 °F (USCG, 1999) - Less dense 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.
–	0.8 g/cm³	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	less than 1 mg/mL at 66 °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, 7.10X10+4 mg/L at 25 °C	[4] Hazardous Substances Data Bank (HSDB)cites Yalkowsky SH, Dannenfelser RM; The AQUASOL dATAbASE of Aqueous Solubility. Fifth ed, Tucson,AZ: Univ Az, College of Pharmacy (1992)
–shown	Solubility in water, g/100ml: 7	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	log Kow = 0.88	[4] 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. 9
–shown	0.88	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
91.5 mmHg	91.5 mmHg 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.
111 mmHgshown	111 mm Hg at 25 °C	[4] 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.
92 mmHg	Vapor pressure, kPa at 20 °C: 12.2	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
111 mmHg	111 [mm Hg] @25 °C	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
−7 °C	20 °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.
−22 °C	-8 °F (-22 °C) (CLOSED CUP)	[4] Hazardous Substances Data Bank (HSDB)cites Fire Protection Guide to Hazardous Materials. 13 ed. Quincy, MA: National Fire Protection Association, 2002., p. 325-9
−12 °Cshown	-12 °C c.c.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
230 °C	446 °F (USCG, 1999)	[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.
218 °C	425 °F 218 °C	[4] Hazardous Substances Data Bank (HSDB)cites Fire Protection Guide to Hazardous Materials. 13 ed. Quincy, MA: National Fire Protection Association, 2002., p. 325-27
230 °Cshown	230 °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: 5
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0.75
H-bond donors: 0
H-bond acceptors: 1
Rotatable bonds: 2
TPSA (Å²): 17.1
Formal charge: 0
XLogP3: 0.9 PubChem
Complexity: 24 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

C66.63%
H11.18%
O22.19%

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: 0.99 Crippen (Wildman and Crippen 1999)
log S (water solubility): -0.78 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.73 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 72.11
log P ≤ 5 (Crippen): 0.99
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 [6].

Flammable

NFPA 704[4]

H225Highly Flammable liquid and vapor

Precautionary statements: P210, P233, P240, P241, P242, P243, P280, P303+P361+P353, P370+P378, P403+P235, P501

View all classifications (2)

[6] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH225
[7] European Chemicals Agency (ECHA) · 2,152 reports · DangerH225, H319

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]
General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[8]
Fresh air, rest.[3]
Remove contaminated clothes. Rinse skin with plenty of water or shower.[3]

Storage

Fireproof. Separated from incompatible materials. See Chemical Dangers. Cool. Keep in the dark. Store in an area without drain or sewer access.[3]
On contact with air butyraldehyde is oxidized readily to the butyric acids. Therefore, storage under inert gas is mandatory.[4]
Store in cool, dry, well ventilated location. Separate from oxidizing materials, amines, strong alkalies, acids, and other reactive hazards. Inside storage should be in a standard flammable liquids storage warehouse, room, or cabinet. Bulk storage should be blanketed with inert gas.[4]
Outside or detached storage is preferred. ...Metal containers involving the transfer of this chemical should be grounded and bonded. Drums must be equipped with self-closing valves, pressure vacuum bungs, and flame arresters. Use only non-sparking tools and equipment, especially when opening and closing containers of this chemical. Sources of ignition such as smoking and open flames, are prohibited where this chemical is used, handled, or stored ina manner that could create a potential fire or explosion hazard.[4]

Incompatibilities

Incompatible with oxidizing materials.[4]
Reacts vigorously with chlorosulfonic acid, (nitric acid), oleum, (sulfuric acid).[4]
Butyraldehyde mixed with chlorosulfonic acid, 70% nitric acid, oleum, or 96% sulfuric acid in closed containers causes the temperature, and pressure to increase.[4]
Mixing n-butyrlaldehyde and chlorosulfonic acid in a closed container caused the temperature and pressure to increase.[4]

Safety data sheets on the supplier’s page: Smolecule, Oakwood Products, ChemShuttle.

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]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[5]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[6]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
[7]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[8]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
[9]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[10]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[11]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[12]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[13]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[14]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

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