2,4-Dichlorophenol

2,4-Dichlorophenol (2,4-DCP) is a chlorinated derivative of phenol with the molecular formula Cl₂C₆H₃OH. It is a white solid that is mildly acidic (pK_a = 7.9). It is produced on a large scale as a precursor to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D).^[4]

2,4-Dichlorophenol

Skeletal formula Ball-and-stick model
Names
Preferred IUPAC name 2,4-Dichlorophenol
Identifiers
CAS Number	120-83-2 Y
3D model (JSmol)	Interactive image
Beilstein Reference	742467
ChEBI	CHEBI:16738 Y
ChEMBL	ChEMBL1143 Y
ChemSpider	8140 Y
ECHA InfoCard	100.004.027
EC Number	204-429-6
Gmelin Reference	261170
KEGG	C02625 Y
PubChem CID	8449
RTECS number	SK8575000
UNII	R669TG1950 Y
UN number	2020
CompTox Dashboard (EPA)	DTXSID1020439
InChI InChI=1S/C6H4Cl2O/c7-4-1-2-6(9)5(8)3-4/h1-3,9H Y Key: HFZWRUODUSTPEG-UHFFFAOYSA-N Y InChI=1/C6H4Cl2O/c7-4-1-2-6(9)5(8)3-4/h1-3,9H Key: HFZWRUODUSTPEG-UHFFFAOYAU
SMILES Clc1cc(Cl)c(O)cc1
Properties
Chemical formula	C6H4Cl2O
Molar mass	163.00 g·mol−1
Appearance	White solid
Odor	Phenolic
Density	1.38 g/cm3
Melting point	43.2 °C (109.8 °F; 316.3 K)[1]
Boiling point	210 °C (410 °F; 483 K)[1]
Solubility in water	50 g/L
Thermochemistry[2]
Std enthalpy of formation (ΔfH⦵298)	−226.4 kJ·mol−1 (s) −156.3 kJ·mol−1 (gas)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H311, H314, H411
Precautionary statements	P260, P264, P270, P273, P280, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P361, P363, P391, P405, P501
NFPA 704 (fire diamond)	0 1 0 COR
Flash point	114 °C (237 °F; 387 K)[3]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	47.0 mg/kg (oral in rats) 790.0 mg/kg (Dermal exposure in mammals)
Safety data sheet (SDS)	External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Production and use

2,4-DCP is produced by chlorination of phenol.^[4]

Annual worldwide production is estimated at 88 million pounds.^[5] It is also a photo-degradation product of the common antibacterial and antifungal agent triclosan along with the dioxin 2,8-dichlorodibenzo-p-dioxin.^[6][7]

Safety

The LD50 is 580 mg/kg (rats, oral). Liquid (molten) 2,4-DCP is readily absorbed through the skin.^[8] Solid 2,4-DCP does not readily absorb through skin and has a lower NFPA H=3 rating (versus H=4 for molten 2,4-DCP). This is primarily caused by instantaneous kidney failure, liver failure, and failure of various other organs.^{[dubious – discuss]}

See also

• Dichlorophenol
• 2,4-dichlorophenol 6-monooxygenase