2,4-Dichlorophenol Explained

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).

Production and use

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

Annual worldwide production is estimated at 88 million pounds.^[1] It is also a photo-degradation product of the common antibacterial and antifungal agent triclosan along with the dioxin 2,8-dichlorodibenzo-p-dioxin.^{[2] [3]}

Safety

The LD50 is 580 mg/kg (rats, oral). Liquid (molten) 2,4-DCP is readily absorbed through the skin.^[4] 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.

See also

• Dichlorophenol
• 2,4-dichlorophenol 6-monooxygenase

Notes and References

1. Desmurs J, Ratton S. Chlorophenols. In: Kirk-Othmer Encyclopedia of Chemical Technology, 4th Edition. Kroschwitz JI, Howe-Grant M, eds. New York: John Wiley and Sons, 1993;6:156–168
2. Singer H, Muller S, Tixier C, Pillonel L . Triclosan: occurrence and fate of a widely used biocide in the aquatic environment: field measurements in wastewater treatment plants, surface waters, and lake sediments. . Environ Sci Technol . 36 . 23 . 4998–5004 . 2002 . 12523412 . 10.1021/es025750i. 2002EnST...36.4998S .
3. Latch DE, Packer JL, Stender BL, VanOverbeke J, Arnold WA, McNeill K . Aqueous photochemistry of triclosan: formation of 2,4-dichlorophenol, 2,8-dichlorodibenzo-p-dioxin, and oligomerization products . Environ. Toxicol. Chem. . 24 . 3 . 517–25 . 2005 . 15779749. 10.1897/04-243R.1. 19322739 .
4. Kintz P, Tracqui A, Mangin P . Accidental death caused by the absorption of 2,4-dichlorophenol through the skin . Arch. Toxicol. . 66 . 4 . 298–9 . 1992 . 1514931 . 10.1007/BF02307178. 23764834 .