4-Fluorobenzoic acid

4-Fluorobenzoic acid (p-fluorobenzoic acid) is an organic compound with the formula C₇H₅FO₂. This colourless solid is a derivative of benzoic acid carboxylic acid. It is a synthetic intermediate.

4-Fluorobenzoic acid

Names
Preferred IUPAC name 4-Fluorobenzoic acid
Other names p-fluorobenzoic acid, para-fluorobenzoic acid, 4-fluoro-benzoic acid
Identifiers
CAS Number	456-22-4 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:20364
ChemSpider	9579
ECHA InfoCard	100.006.600
EC Number	207-259-0
PubChem CID	9973
UNII	V5ROO2HOU4 Y
CompTox Dashboard (EPA)	DTXSID9060023
InChI InChI=1S/C7H5FO2/c8-6-3-1-5(2-4-6)7(9)10/h1-4H,(H,9,10)
SMILES O=C(O)c1ccc(F)cc1
Properties
Chemical formula	C7H5FO2
Molar mass	140.113 g·mol−1
Appearance	white solid
Density	1.479 g/cm3
Melting point	184 °C (363 °F; 457 K)
Boiling point	253.687 °C (488.637 °F; 526.837 K) at 760 mmHg
Solubility in water	1200 mg/L
log P	2.07
Acidity (pKa)	4.14
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Irritates lungs, eyes, skin
GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H302, H318
Precautionary statements	P264, P270, P280, P301+P312, P305+P351+P338, P310, P330, P501
Flash point	107.226 °C (225.007 °F; 380.376 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

4-Fluorobenzoic acid is commercially available. It may be prepared via the Schiemann reaction, in which a 4-aminobenzoic acid, protected as the ethyl ester, is diazotised and then fluoride introduced using tetrafluoroborate. Hydrolysis of the ester converts it back to the free acid.^[2]

4-Fluorobenzoic acid has been observed to form by the aerobic biotransformation of 4-fluorocinnamic acid.^[3]

See also

• 2-Fluorobenzoic acid, the ortho isomer
• 3-Fluorobenzoic acid, the meta isomer