4-Chlorophenol

4-Chlorophenol is an organic compound with the formula C₆H₄ClOH. It is one of three monochlorophenol isomers. It is a colorless or white solid that melts easily and exhibits significant solubility in water. Its pK_a is 9.41.

4-Chlorophenol

Names
Preferred IUPAC name 4-Chlorophenol
Other names p-Chlorophenol
Identifiers
CAS Number	106-48-9 Y
3D model (JSmol)	Interactive image
Beilstein Reference	507004
ChEBI	CHEBI:28078
ChEMBL	ChEMBL57053
ChemSpider	13875219
DrugBank	DB13154
ECHA InfoCard	100.003.094
EC Number	203-402-6
Gmelin Reference	2902
KEGG	C02124
PubChem CID	4684
RTECS number	SK2800000
UNII	3DLC36A01X
UN number	2020
CompTox Dashboard (EPA)	DTXSID1021871
InChI InChI=1S/C6H5ClO/c7-5-1-3-6(8)4-2-5/h1-4,8H Key: WXNZTHHGJRFXKQ-UHFFFAOYSA-N
SMILES C1=CC(=CC=C1O)Cl
Properties
Chemical formula	C6H5ClO
Molar mass	128.56 g·mol−1
Appearance	White solid
Density	1.2651 g/cm3 at 40 °C[1]
Melting point	43.1 °C (109.6 °F; 316.2 K)[1]
Boiling point	219 °C (426 °F; 492 K)[1]
Solubility in water	27.1 g/L
Acidity (pKa)	9.41[2]
Magnetic susceptibility (χ)	−77.7·10−6 cm3/mol[3]
Refractive index (nD)	1.5579[1]
Structure[4]
Dipole moment	2.11 D
Thermochemistry[5]
Std enthalpy of formation (ΔfH⦵298)	−197.7 kJ·mol−1 (s) −181.3 kJ·mol−1 (l)
Enthalpy of fusion (ΔfH⦵fus)	14.1 kJ·mol−1
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H290, H301, H302, H312, H314, H332, H411
Precautionary statements	P234, P260, P261, P264, P270, P271, P273, P280, P301+P310, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P363, P390, P391, P404, P405, P501
Flash point	121 °C (250 °F; 394 K)[6]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation and reaction

It is prepared by chlorination of phenol, preferably in polar solvents, which tends to yield the 4-chloro derivative. Direct chlorination of molten phenol favors the formation of 2-chlorophenol.^[7]

It once was produced on a large scale as a precursor to hydroquinone.^[7] It is a classic precursor, upon reaction with phthalic anhydride, to quinizarin.^[8] The commercial dye quinizarin is produced by the reaction of phthalic anhydride and 4-chlorophenol followed by hydrolysis of the chloride.^[9]

Clofibrate, a drug for controlling the high cholesterol and triacylglyceride level in the blood, is derived from 4-chlorophenol.