Ascorbic acid (C6H8O6): structure, properties and hazards

Names and identifiers

IUPAC name: (2R)-2-[(1S)-1,2-dihydroxyethyl]-3,4-dihydroxy-2H-furan-5-one
Synonyms: vitamin C, L-ascorbic acid, ascorbate
+ 39 more
E300, scurvy, l-ascorbic acid, L(+)-Ascorbic acid, Ascoltin, Ascorbicap, Cevitamic acid, Allercorb, Ascorbajen, Ascorin, Ascorteal, Ascorvit, Cantaxin, Cebicure, Cegiolan, Ceglion, Cenetone, Cergona, Cetemican, Cevatine, Redoxon, Viscorin, Vitacimin, Vitacin, Cantan, Cebion, Cereon, Cecon, Celin, Cevex, Hicee, Catavin C, Laroscorbine, Testascorbic, Ascorbutina, Celaskon, Cescorbat, Cevitamin, Citriscorb
Molecular formula: C₆H₈O₆
Empirical formula: C₃H₄O₃
Molecular weight: 176.12 g/mol
Exact mass: 176.03209
CAS number: 50-81-7
PubChem CID: 54670067
Canonical SMILES: C(C(C1C(=C(C(=O)O1)O)O)O)O
Isomeric SMILES: C([C@@H]([C@@H]1C(=C(C(=O)O1)O)O)O)O
InChI: InChI=1S/C6H8O6/c7-1-2(8)5-3(9)4(10)6(11)12-5/h2,5,7-10H,1H2/t2-,5+/m0/s1
InChIKey: CIWBSHSKHKDKBQ-JLAZNSOCSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: White crystals (plates or needles)[4]
5 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– L-ascorbic acid is a white to very pale yellow crystalline powder with a pleasant sharp acidic taste. Almost odorless. (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)
– ODOURLESS WHITE-TO-SLIGHTLY-YELLOW CRYSTALS OR POWDER. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown White crystals (plates or needles) [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. 103
– White to slightly yellow crystals or powder ... gradually darkens on exposure to light [4] Hazardous Substances Data Bank (HSDB)cites FCC; Food chemicals codex. Committee on Food Chemicals Codex, Food and Nutrition Board, Institute of Medicine. 5th. Washington, DC: National Academy Press p. 36 (2003)
Odor: Odorless[4]
Melting point: 190 to 192 °C (374 to 378 °F) (decomposes) (NTP, 1992)[1]
Density: 1.65 (NTP, 1992) - Denser than water[1]
Solubility in water: Solubility in water, g/100ml at 20 °C: 33 (freely soluble)[3]
4 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 73 °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.
– 1 g dissolves in about 3 ml of water. [4] Hazardous Substances Data Bank (HSDB)cites Chase et al; Remington's Pharmaceutical Sciences 14th ed. Mack Publ Co. Easton, PA p. 1036 (1970)
– The solubility in g/mL is 0.33 in water, 0.033 in 95 wt% ethanol, 0.02 in absolute ethanol, 0.01 in glycerol USP, 0.05 in propylene glycol. [4] Hazardous Substances Data Bank (HSDB)cites Kuellmer V; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). New York, NY: John Wiley & Sons; Ascorbic Acid. Online Posting Date: Apr 16, 2001.
–shown Solubility in water, g/100ml at 20 °C: 33 (freely soluble) [3] ILO-WHO International Chemical Safety Cards (ICSCs)
log P: -2.15[3]
2 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
– log Kow = -1.85 [4] Hazardous Substances Data Bank (HSDB)cites Avdeef A; Seminar on Ionization and Lipophilicity. Log P values measured by pION Inc., Brookline, MA (1997)
–shown -2.15 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
pKa: pKa = 4.70 at 10 °C[4]
Autoignition temperature: 660 °C (1220 °F, NTP 1992)[1]
2 values
Sources disagree; from CAMEO Chemicals, the most authoritative.
Value As written Source
660 °Cshown 1220 °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.
380 °C 380 °C [4] Hazardous Substances Data Bank (HSDB)cites Organization for Economic Cooperation and Development; Screening Information Data Set for L-Ascorbic acid CAS 50-81-7. Available from, as of January 13, 2009: https://www.chem.unep.ch/irptc/sids/OECDSIDS/sidspub.html

Value	As written	Source
–	L-ascorbic acid is a white to very pale yellow crystalline powder with a pleasant sharp acidic taste. Almost odorless. (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)
–	ODOURLESS WHITE-TO-SLIGHTLY-YELLOW CRYSTALS OR POWDER.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown	White crystals (plates or needles)	[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. 103
–	White to slightly yellow crystals or powder ... gradually darkens on exposure to light	[4] Hazardous Substances Data Bank (HSDB)cites FCC; Food chemicals codex. Committee on Food Chemicals Codex, Food and Nutrition Board, Institute of Medicine. 5th. Washington, DC: National Academy Press p. 36 (2003)

Value	As written	Source
–	greater than or equal to 100 mg/mL at 73 °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.
–	1 g dissolves in about 3 ml of water.	[4] Hazardous Substances Data Bank (HSDB)cites Chase et al; Remington's Pharmaceutical Sciences 14th ed. Mack Publ Co. Easton, PA p. 1036 (1970)
–	The solubility in g/mL is 0.33 in water, 0.033 in 95 wt% ethanol, 0.02 in absolute ethanol, 0.01 in glycerol USP, 0.05 in propylene glycol.	[4] Hazardous Substances Data Bank (HSDB)cites Kuellmer V; Kirk-Othmer Encyclopedia of Chemical Technology. (2001). New York, NY: John Wiley & Sons; Ascorbic Acid. Online Posting Date: Apr 16, 2001.
–shown	Solubility in water, g/100ml at 20 °C: 33 (freely soluble)	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	log Kow = -1.85	[4] Hazardous Substances Data Bank (HSDB)cites Avdeef A; Seminar on Ionization and Lipophilicity. Log P values measured by pION Inc., Brookline, MA (1997)
–shown	-2.15	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
660 °Cshown	1220 °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.
380 °C	380 °C	[4] Hazardous Substances Data Bank (HSDB)cites Organization for Economic Cooperation and Development; Screening Information Data Set for L-Ascorbic acid CAS 50-81-7. Available from, as of January 13, 2009: https://www.chem.unep.ch/irptc/sids/OECDSIDS/sidspub.html

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: 12
Rings: 1
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0.5
H-bond donors: 4
H-bond acceptors: 6
Rotatable bonds: 2
TPSA (Å²): 107.2 computed here · PubChem 107
Formal charge: 0
XLogP3: -1.6 PubChem
Complexity: 232 PubChem
Stereocenters: 2 definedCIP: C3: S · C5: R
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

C40.92%
H4.58%
O54.50%

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: -1.41 Crippen (Wildman and Crippen 1999)
log S (water solubility): 0.09 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.68 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 176.12
log P ≤ 5 (Crippen): -1.41
H-bond donors ≤ 5: 4
H-bond acceptors ≤ 10: 6

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 97.3% (572 of 588) of all reports.[5]

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.[3]
Rinse with plenty of water (remove contact lenses if easily possible).[3]
Rinse mouth.[3]

Storage

Separated from strong oxidants and strong bases.[3]
Solutions of ascorbic acid are rapidly oxidized in air and in alkaline media; the drug should be protected from air and light.[4]

Safety data sheets on the supplier’s page: Alfa Chemistry, AbaChemScene, Sigma-Aldrich.

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]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[6]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[7]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[8]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
[9]MassBank of North America (MoNA) · CC BY 4.0 · 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

Dehydroascorbic acid 58%

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

Isomers in the library

Glucurono-6,3-lactone