2,4,5-T

2,4,5-Trichlorophenoxyacetic acid

Names
IUPAC name (2,4,5-Trichlorophenoxy)acetic acid
Other names 2,4,5-Trichlorophenoxyacetic acid 2,4,5-T Trioxone
Identifiers
CAS Number	93-76-5 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:27903 Y
ChEMBL	ChEMBL194458 Y
ChemSpider	1435 Y
ECHA InfoCard	100.002.068
KEGG	C07100 Y
RTECS number	AJ8400000
UNII	9Q963S4YMX Y
InChI InChI=1S/C8H5Cl3O3/c9-4-1-6(11)7(2-5(4)10)14-3-8(12)13/h1-2H,3H2,(H,12,13) Y Key: SMYMJHWAQXWPDB-UHFFFAOYSA-N Y InChI=1/C8H5Cl3O3/c9-4-1-6(11)7(2-5(4)10)14-3-8(12)13/h1-2H,3H2,(H,12,13) Key: SMYMJHWAQXWPDB-UHFFFAOYAR
SMILES Clc1cc(OCC(=O)O)c(Cl)cc1Cl
Properties
Chemical formula	C8H5Cl3O3
Molar mass	255.48 g/mol
Appearance	Off-white to yellow crystalline solid
Odor	odorless
Density	1.80 g/cm3, 20 °C
Melting point	154 to 158 °C (309 to 316 °F; 427 to 431 K)
Boiling point	decomposes
Solubility in water	238 mg/kg (30 °C)
Vapor pressure	6995133322387415000♠1×10−7 mmHg
Hazards
R-phrases	22-36/37/38-50/53
S-phrases	24-60-61
Lethal dose or concentration (LD, LC):
LD50 (median dose)	381 mg/kg (guinea pig, oral) 300 mg/kg (rat, oral) 425 mg/kg (hamster, oral) 242 mg/kg (mouse, oral)
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 10 mg/m3
REL (Recommended)	TWA 10 mg/m3
IDLH (Immediate danger)	250 mg/m3
Related compounds
Related compounds	2,4-D auxin
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

2,4,5-Trichlorophenoxyacetic acid (also known as 2,4,5-T), a synthetic auxin, is a chlorophenoxy acetic acid herbicide used to defoliate broad-leafed plants. It was developed in the late 1940s and was widely used in the agricultural industry until being phased out, starting in the late 1970s due to toxicity concerns. Agent Orange, a defoliant used by the British in the Malayan Emergency and the U.S. in the Vietnam War, was equal parts 2,4,5-T and 2,4-D (2,4-dichlorophenoxyacetic acid). 2,4,5-T itself is toxic with a NOAEL of 3 mg/kg/day and a LOAEL of 10 mg/kg/day. Additionally, the manufacturing process for 2,4,5-T contaminates this chemical with trace amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD is a carcinogenic persistent organic pollutant with long-term effects on the environment. With proper temperature control during production of 2,4,5-T, TCDD levels can be held to about .005 ppm. Before the TCDD risk was well-understood, early production facilities lacked proper temperature controls and individual batches tested later were found to have as much as 60 ppm of TCDD.

In 1970, the United States Department of Agriculture halted the use of 2,4,5-T on all food crops except rice, and in 1985, the EPA terminated all remaining uses in the U.S. of this herbicide. The international trade of 2,4,5-T is restricted by the Rotterdam Convention. 2,4,5-T has since largely been replaced by dicamba and triclopyr.

Human health effects from 2,4,5-T at low environmental doses or at biomonitored levels from low environmental exposures are unknown. Intentional overdoses and unintentional high dose occupational exposures to chlorophenoxy acid herbicides have resulted in weakness, headache, dizziness, nausea, abdominal pain, myotonia, hypotension, renal and hepatic injury, and delayed neuropathy.. Cometabolism of 2,4,5-T is possible to produce 3,5-dichlorocatechol which, in turn, can be degraded by Pseudomona bacteria. IARC considers the chlorophenoxyacetic acids group of chemicals as possibly carcinogenic to humans.