Boric acid

Athanor · official

BH₃O₃ · 61.84 g/mol

Also called boracic acid, orthoboric acid

Inorganic

Open in Athanor

Drawn from its SMILES with RDKit

DangerMay damage fertility; May damage the unborn child

Names and identifiers

IUPAC name: boric acid
Synonyms: boracic acid, orthoboric acid, Orthoboric acid
+ 37 more
Boracic acid, Borofax, Boron hydroxide, Boric acid (H3BO3), Boron trihydroxide, Basilit B, Three Elephant, Boric acid (BH3O3), Trihydroxyborane, Trihydroxyborone, Flea Prufe, Super Flea Eliminator, Orthoborsaeure, Borsaeure, Borsaure, Orthoboric acid (B(OH)3), NCI-C56417, Dr.'s 1 Flea Terminator DT, Dr.'s 1 Flea Terminator DFPBO, Collyrium Eye Wash, hydrogen orthoborate, Dr.'s 1 Flea Terminator DF, B(OH)3, Boricum acidum, Dr.'s 1 Flea Terminator DTPBO, trihydroxidoboron, NSC-81726, DTXSID1020194, Orthoboric acid (H3BO3), INS NO.284, R57ZHV85D4, INS-284, Boric acid (h(sub 3)bo(sub 3)), DTXCID10194, E-284, CHEBI:33118, [B(OH)3]
Molecular formula: BH₃O₃
Empirical formula: BH₃O₃
Molecular weight: 61.84 g/mol
Exact mass: 62.01752
CAS number: 10043-35-3
PubChem CID: 7628
Canonical SMILES: B(O)(O)O
Isomeric SMILES: B(O)(O)O
InChI: InChI=1S/BH3O3/c2-1(3)4/h2-4H
InChIKey: KGBXLFKZBHKPEV-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: White waxy triclinic solid plates[5]
5 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Boric acid is an odorless white solid. Melting point 171 °C. Sinks and mixes with water. (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.
– Dry Powder; Other Solid; Large Crystals; Dry Powder; Large Crystals; Liquid; Other Solid [2] EPA Chemical Data Reporting (CDR)
– ODOURLESS COLOURLESS CRYSTALS OR WHITE POWDER. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– Odorless white solid. [4] Occupational Safety and Health Administration (OSHA)
–shown White waxy triclinic solid plates [5] Hazardous Substances Data Bank (HSDB)cites Bingham, E.; Cohrssen, B.; Powell, C.H.; Patty's Toxicology Volumes 1-9 5th ed. John Wiley & Sons. New York, N.Y. (2001)., p. V3: 521
Melting point: 170.9 °C[6]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source
171 °C 340 °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.
171 °C 340 °F [4] Occupational Safety and Health Administration (OSHA)
170.9 °Cshown 170.9 °C [6] PAC Chemical Database, U.S. Department of Energy
Boiling point: 300 °C (572 °F) at 760 mmHg (decomposes) (NTP, 1992)[1]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
300 °Cshown 572 °F at 760 mmHg (decomposes) (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.
300 °C 572 °F [4] Occupational Safety and Health Administration (OSHA)
Density: 1.435 @25 °C[6]
4 values
3 of 4 sources agree on it (most common value).
Value As written Source
– 1.435 at 68 °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): 1.5 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 1.435 [4] Occupational Safety and Health Administration (OSHA)
–shown 1.435 @25 °C [6] PAC Chemical Database, U.S. Department of Energy
Solubility in water: Solubility in water, g/100ml at 20 °C: 5.6[3]
5 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– 10 to 50 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.
– Solubility: in glycerol 17.5% at 25 °C; ethylene glycol 18.5% at 25 °C; in methanol 173.9 g/L at 25 °C; in ethanol 94.4 g/L at 25 °C; in acetone 0.6% at 25 °C; ethyl acetate 1.5% at 25 °C [5] Hazardous Substances Data Bank (HSDB)cites Schubert D; Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2011). New York, NY: John Wiley & Sons; Boron Oxides, Boric Acid, and Borates. Online Posting Date: 15 April 2011
– Water solubility: 2.52% at 0 °C; 3.49% at 10 °C; 4.72% at 20 °C; 6.23% at 30 °C; 8.08% at 40 °C; 10.27% at 50 °C; 12.97% at 60 °C; 15.75% at 70 °C; 19.10% at 80 °C; 23.27% at 90 °C; 27.53% at 100 °C [5] Hazardous Substances Data Bank (HSDB)cites Schubert D; Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2011). New York, NY: John Wiley & Sons; Boron Oxides, Boric Acid, and Borates. Online Posting Date: 15 April 2011
– In water, 5.0X10+4 mg/L at 25 °C [5] Hazardous Substances Data Bank (HSDB)cites PMID:2205893 Shiu WY et al; Rev Environ Contam Toxicol 116: 15-187 (1990)
–shown Solubility in water, g/100ml at 20 °C: 5.6 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
log P: -1.09[3]
2 values
Sources disagree; from ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative.
Value As written Source
– log Kow = 0.175 [5] Hazardous Substances Data Bank (HSDB)cites WHO; Environmental Health Criteria 204, Boron. World Health Org (1998). Available from, as of Oct 4, 2011: https://www.inchem.org/documents/ehc/ehc/ehc204.htm
–shown -1.09 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
pKa: Reported, but no value passed the checks.
The value and why
Ka = 5.80X10-10 at 25 °C (pKa = 9.24) (could not be read; source [5])
Vapor pressure: 1.6 × 10⁻⁶ mmHg at 25 °C (2.136 × 10⁻⁴ Pa)[5]

Value	As written	Source
–	Boric acid is an odorless white solid. Melting point 171 °C. Sinks and mixes with water. (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.
–	Dry Powder; Other Solid; Large Crystals; Dry Powder; Large Crystals; Liquid; Other Solid	[2] EPA Chemical Data Reporting (CDR)
–	ODOURLESS COLOURLESS CRYSTALS OR WHITE POWDER.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	Odorless white solid.	[4] Occupational Safety and Health Administration (OSHA)
–shown	White waxy triclinic solid plates	[5] Hazardous Substances Data Bank (HSDB)cites Bingham, E.; Cohrssen, B.; Powell, C.H.; Patty's Toxicology Volumes 1-9 5th ed. John Wiley & Sons. New York, N.Y. (2001)., p. V3: 521

Value	As written	Source
171 °C	340 °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.
171 °C	340 °F	[4] Occupational Safety and Health Administration (OSHA)
170.9 °Cshown	170.9 °C	[6] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
300 °Cshown	572 °F at 760 mmHg (decomposes) (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.
300 °C	572 °F	[4] Occupational Safety and Health Administration (OSHA)

Value	As written	Source
–	1.435 at 68 °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): 1.5	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	1.435	[4] Occupational Safety and Health Administration (OSHA)
–shown	1.435 @25 °C	[6] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	10 to 50 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.
–	Solubility: in glycerol 17.5% at 25 °C; ethylene glycol 18.5% at 25 °C; in methanol 173.9 g/L at 25 °C; in ethanol 94.4 g/L at 25 °C; in acetone 0.6% at 25 °C; ethyl acetate 1.5% at 25 °C	[5] Hazardous Substances Data Bank (HSDB)cites Schubert D; Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2011). New York, NY: John Wiley & Sons; Boron Oxides, Boric Acid, and Borates. Online Posting Date: 15 April 2011
–	Water solubility: 2.52% at 0 °C; 3.49% at 10 °C; 4.72% at 20 °C; 6.23% at 30 °C; 8.08% at 40 °C; 10.27% at 50 °C; 12.97% at 60 °C; 15.75% at 70 °C; 19.10% at 80 °C; 23.27% at 90 °C; 27.53% at 100 °C	[5] Hazardous Substances Data Bank (HSDB)cites Schubert D; Kirk-Othmer Encyclopedia of Chemical Technology. (1999-2011). New York, NY: John Wiley & Sons; Boron Oxides, Boric Acid, and Borates. Online Posting Date: 15 April 2011
–	In water, 5.0X10+4 mg/L at 25 °C	[5] Hazardous Substances Data Bank (HSDB)cites PMID:2205893 Shiu WY et al; Rev Environ Contam Toxicol 116: 15-187 (1990)
–shown	Solubility in water, g/100ml at 20 °C: 5.6	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	log Kow = 0.175	[5] Hazardous Substances Data Bank (HSDB)cites WHO; Environmental Health Criteria 204, Boron. World Health Org (1998). Available from, as of Oct 4, 2011: https://www.inchem.org/documents/ehc/ehc/ehc204.htm
–shown	-1.09	[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: 4
Rings: 0
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0
H-bond donors: 3
H-bond acceptors: 3
Rotatable bonds: 0
TPSA (Å²): 60.7
Formal charge: 0
Complexity: 8 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

H4.89%
B17.49%
O77.62%

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: -2.05 Crippen (Wildman and Crippen 1999)
log S (water solubility): 1.07 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.43 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 61.83
log P ≤ 5 (Crippen): -2.05
H-bond donors ≤ 5: 3
H-bond acceptors ≤ 10: 3

Passes all four rules.

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].

Health hazard

H360FDMay damage fertility; May damage the unborn child

Precautionary statements: P203, P280, P318, P405, P501

View all classifications (5)

[7] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH360FD
[7] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH360FD
[8] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for < 0.1% (1 of 2123) of reports.
[8] European Chemicals Agency (ECHA) · 2,123 reports · DangerH360, H360FD
[8] European Chemicals Agency (ECHA) · 241 reports · DangerH360

Exposure limits

TLV: (inhalable fraction): 2 mg/m[3]
TLV-TWA (Time Weighted Average): 2 mg/m³ (inhalable particulate matter) [2004][4]
TLV-STEL (Short Term Exposure Limit): 6 mg/m³ (inhalable particulate matter) [2004][4]
MAK (Maximale Arbeitsplatz Konzentration): (inhalable fraction): 10 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.[3]
Rinse and then wash skin with water and soap.[3]
Rinse with plenty of water (remove contact lenses if easily possible).[3]

Storage

Separated from strong bases.[3]
Preserve in well-closed containers.[5]

Incompatibilities

During an attempt to make triacetyl borate, a mixture of boric acid and acetic anhydride exploded when heated to 58-60 °C.[5]
A mixture of potassium and (boric acid) ... May explode on impact ...[5]

Safety data sheets on the supplier’s page: ChemoSapiens, Strem Chemicals, Inc., Sigma-Aldrich.

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

Spectra

NMRNMRShiftDB
11B NMRSpectraBase
17O NMRSpectraBase
GC-MSNIST Mass Spectrometry Data Center · SpectraBase
FTIRSpectraBase (KBr WAFER)
ATR-IRSpectraBase (Bio-Rad FTS · ATR-Neat (DuraSamplIR II))
RamanSpectraBase (Bio-Rad FTS 175C with Raman accessory · 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]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]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.