Synonyms: 1,1′-dimethyl-4,4′-bipyridinediium dichloride; 1,1′-dimethyl-4,4′-bipyridinium dichloride; 1,1′-dimethyl-4,4′-bipyridylium dichloride (IUPAC); methyl viologen dichloride
CAS No.: 1910-42-5
EC No.: 217-615-7
Molecular Weight: 257.2
Form: Colourless, hygroscopic crystals.
M.p.: Decomposes at c. 340 °C
V.p.: <1 × 10-2 mPa (25 °C)
S.g.: 1.5 (25 °C)
Solubility: In water c. 620 g/l (pH c. 5–9, 20 °C). In methanol 143 g/l (20 °C); practically insoluble in most other organic solvents.
Stability: Decomposes at c. 340 °C. Hydrolytically stable in alkaline, neutral and acidic media. Photolytically stable in aqueous solution at pH 7.
Used for broad-spectrum control of broad-leaved weeds and grasses in fruit orchards (including citrus), plantation crops, forestry, etc. Also used for general weed control on non-crop land; as a defoliant for cotton and hops; for destruction of potato haulms; as a desiccant for pineapples, sugar cane, soya beans and sunflowers; for strawberry runner control; and in pasture renovation.
Risks and Safety Information
Very Toxic pesticide. Class 6.1
Acute oral LD50(rats) 129 to 157, Skin and eye Acute percutaneous LD50(rats) >911mg/kg. Irritating to skin and eyes (rabbits). Absorption through intact human skin is minimal; exposures can cause irritation and a delay in the healing of cuts and wounds; can cause temporary damage to nails. Not a skin sensitiser (guinea pigs). Birds Acute oral LD50(bobwhite quail) 175,LC50 (5d) for bobwhite quail 981,Fish LC50 (96h) for rainbow trout 26, Algae EbC50 (96 h) for green algae 0.10mg/l. Bees LD50 (120h) (oral) 15μg/bee; (contact) 70μg/bee.