Gourt Home::Gourt :: 2,4,5-Trichlorophenoxyacetic acid
| 2,4,5-Trichlorophenoxyacetic acid | |
|---|---|
| General | |
| Systematic name | (2,4,5-trichlorophenoxy)acetic acid) |
| Other names | 2,4,5-trichlorophenoxyacetic acid 2,4,5-T trioxone |
| Molecular formula | C8H5Cl3O3 |
| SMILES | OC(COC1=CC(Cl)=C(Cl)C=C1Cl)=O |
| Molar mass | 255.49 g/mol |
| Appearance | off-white to yellow crystalline solid |
| CAS number | * |
| Properties | |
| Density and phase | 1.80 g/cm3, 20 °C |
| Solubility in water | 238 mg/kg (30 °C) |
| Melting point | 154-158 °C |
| Boiling point | ? °C (? K) |
| Acidity (pKa) | ? |
| Viscosity | ? cP at ? °C |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | ? |
| NFPA 704 | |
| Flash point | ? °C |
| R/S statement | R: 22-36/37/38-50/53 S: 24-60-61 |
| RTECS number | AJ8400000 |
| Supplementary data page | |
| Structure and properties | n, εr, etc. |
| Thermodynamic data | Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related compounds | 2,4-D auxin |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Chemical infobox | |
2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) is an herbicide used to defoliate broad leafed plants. It was developed in the late 40's and had been widely used in the agricultural industry for many years until being phased out starting in the late 1970s due to toxicity concerns.
2,4,5-T itself is of only moderate toxicity, with oral LD50 of 389 mg/kg in mice and 500 mg/kg in rats. However, 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 reported to be extremely toxic to humans, however this is disputed. 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 Department of Agriculture halted the use of 2,4,5-T on all food crops except rice. In 1985, the EPA terminated all uses of this herbicide on rice fields as well as all non-crop sites. 2,4,5-T has since largely been replaced by dicamba and triclopyr.
Apart from agricultural uses, 2,4,5-T is also a major ingredient in Agent Orange, an herbicide blend used by the U.S. military in Vietnam between January 1965 and April 1970 as a defoliant. Agent Orange was a mixture of 2,4,5-T, 2,4-dichlorophenoxyacetic acid (2,4-D) and picloram. Because of TCDD contamination in the 2,4,5-T component, it has been blamed for serious illnesses in many veterans who were exposed to it. However, research on populations exposed to its dioxin contaminant have been inconsistent and inconclusive. Agent Orange often had much higher levels of TCDD than 2,4,5-T used in the US.
External links
"2,4,5-Trichlorophenoxyacetic acid"