Benzoic acid
An aromatic carboxylic acid used to connect acid–base extraction with organic structure.
- Formula
- C7H6O2
- Functional group
- Carboxylic acids
- Molar mass
- 122.12 g/mol
- Also known as
- Dracylic acid, benzenecarboxylic acid, Benzeneformic acid, Carboxybenzene, phenylformic acid, Benzenemethanoic acid
Overview
An aromatic carboxylic acid used to connect acid–base extraction with organic structure.
A carboxyl group is bonded directly to a benzene ring. Converting the acid into a benzoate salt changes its charge and can change its distribution between aqueous and organic phases. Recovery by acidification depends on the resulting solubility and experimental conditions.
Identifiers
- Formula
- C7H6O2
- Functional group
- Carboxylic acids
- Molar mass
- 122.12 g/mol
- Also known as
- Dracylic acid, benzenecarboxylic acid, Benzeneformic acid, Carboxybenzene, phenylformic acid, Benzenemethanoic acid
Chemical identifiers
- SMILES
- C1=CC=C(C=C1)C(=O)O
- InChI
- InChI=1S/C7H6O2/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9)
- PubChem CID
- 243
Properties
- Melting Point
- 122.35 °C
- Boiling Point
- 249.2 °C at 760 mm Hg
- Density
- 1.2659 g/cu cm at 15 °C
- Water solubility
- In water, 3.5X10+3 mg/L at 25 °C
Diagnostic tests
Hydrogencarbonate acid-group test
- Reagent
- aqueous sodium hydrogencarbonate
- Conditions
- Bring a small sample into contact with the aqueous reagent.
- Positive observation
- Effervescence accompanies formation of carbon dioxide and benzoate.
- Negative observation
- No effervescence with an unhydrolysed neutral ester control.
- Interpretation
- The carboxylic acid proton reacts with hydrogencarbonate.
- Scope
- Expected positive for benzoic acid.
- Limitations
- Low water solubility can slow contact. Other acids can produce the same response.
- Evidence
- established acid–base chemistry
Related compounds
- Carboxylic acids
An aromatic carboxylic acid used to connect acid–base extraction with organic structure.
Connected reactions
- Side chain oxidation: Toluene → Benzoic acid
Toluene gives benzoic acid through side-chain oxidation.
- Complete oxidation: Benzyl alcohol → Benzoic acid
Oxidation first changes the benzylic CH2OH group into an aldehyde and then into carboxylate under the alkaline conditions. Acid work-up gives benzoic acid; the ring is retained while the side-chain carbon becomes more oxidised.
- Aldehyde oxidation: Benzaldehyde → Benzoic acid
Water reversibly adds to the aldehyde to form a hydrate, which can then be oxidised. The aldehyde carbon becomes the acid carbonyl carbon; acid work-up converts the initially formed benzoate into benzoic acid.
- Acyl chloride preparation: Benzoic acid → Benzoyl chloride
Reaction with phosphorus(V) chloride replaces the carboxyl OH group with chlorine, retaining the acyl carbon and aromatic ring. The new acyl chloride is more susceptible to nucleophilic substitution, while POCl3 and HCl account for the remaining atoms.
- Esterification: Benzoic acid → Ethyl benzoate
Acid activation allows ethanol to add to benzoic acid; proton transfers and water loss produce ethyl benzoate. The aromatic ring stays intact throughout the acyl substitution.
References
- PubChem Compound Summary: Benzoic acid (CID 243)National Center for Biotechnology Information · PubChem
Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.
- OpenStax Organic Chemistry: Structure and properties of carboxylic acidsJohn McMurry · OpenStax · 2023
Supports the qualitative structural interpretation of the recorded molecular structure; no new physical measurement or verified preparative yield is claimed.
- Hazardous Substances Data Bank (HSDB): Benzoic acid — melting pointHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/243#section=Melting-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 3-38
- Hazardous Substances Data Bank (HSDB): Benzoic acid — boiling pointHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/243#section=Boiling-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 3-38
- Hazardous Substances Data Bank (HSDB): Benzoic acid — densityHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/243#section=Density. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Haynes, W.M. (ed.) CRC Handbook of Chemistry and Physics. 91st ed. Boca Raton, FL: CRC Press Inc., 2010-2011, p. 3-38
- Hazardous Substances Data Bank (HSDB): Benzoic acid — solubilityHazardous Substances Data Bank (HSDB)
Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/243#section=Solubility. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Yalkowsky, S.H., He, Yan, Jain, P. Handbook of Aqueous Solubility Data Second Edition. CRC Press, Boca Raton, FL 2010, p. 368
- Compound confusion: acid and ester comparisonsRoyal Society of Chemistry · RSC Education
Source-supported qualitative reference observations.