| Names | |
|---|---|
|  Preferred IUPAC name  3,5-dichloro-4-hydroxybenzonitrile  | |
| Identifiers | |
3D model (JSmol)  | |
| ECHA InfoCard | 100.015.976 | 
| EC Number | 
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 PubChem CID  | |
| UNII | |
 CompTox Dashboard (EPA)  | |
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| Properties | |
| C7H3Cl2NO | |
| Molar mass | 188.01 g·mol−1 | 
| Appearance | Off-white solid [1] | 
| Melting point | 140 °C (284 °F; 413 K) [2] | 
| Slightly soluble [3] | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards  | Toxic, harmful to aquatic life, irritant | 
| GHS labelling: [1] | |
|   | |
| Danger | |
| H301, H311, H315, H319, H331, H335 | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)  | 200 mg/kg (oral, rat) [4] | 
LC50 (median concentration)  | 21.4-27.5mg/L (96h, Pimephales promelas) [1] | 
| Related compounds | |
Related compounds  | Ioxynil, Bromoxynil, Bromoxynil octanoate | 
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).  | |
Chloroxynil is a postemergent [5] benzonitrile herbicide, used to control broad leaved weeds on cereal crops. It was manufactured by Rhone-Poulenc and May & Baker, and is now considered obsolete, though its usage may continue. [4]
Chloroxynil was developed as a variant of bromoxynil, which is identical except for bromines replacing chloroxynil's chlorines. A 1972 study found chloroxynil less injurious to alfalfa and red clover, but also less potent at controlling broadleaf weeds. [6]
Chloroxynil's MoA inhibits electron transfer in the photosystem II receptor. [7] Its HRAC group is Group C, (Australia) C3 (global) or 6 (numeric). [4]
Chloroxynil can greatly improve the speed and efficiency of agrobacterium-mediated transformation of plants. Compared to the control, acetosyringone was 6 times faster, and chloroxynil was 60 times faster. Chloroxynil's related herbicides were also tested: bromoxynil was 18 times faster than control but caused plant damage, and ioxynil showed no significant improvement. [8]
In soil, chloroxynil lasts about a month in aerobic soil (soil with sufficient oxygen to support microbial activity), or about two weeks in anaerobic soil. [5] Sunlight can photochemically degrade it, by splitting off the chlorine atoms. [9]
Chloroxynil was used on wheat, barley, oats, lucerne, sorghum and fax, to control pigweed, mayweed, knotweed, shepherd's purse, goosefoot and stinkweed. [4]