Nomeclature:
IUPAC name 1,1′-dimethyl-4,4′-bipyridinediium dichloride; 1,1′-dimethyl-4,4′-bipyridinium dichloride; 1,1′-dimethyl-4,4′-bipyridylium dichloride
Chemical Abstracts name 1,1′-dimethyl-4,4′-bipyridinium dichloride
Other names methyl viologen CAS RN [1910-42-5]; [2074-50-2] bis(methyl sulfate) EEC no. 217-615-7 Development codes PP148; PP910 for bis(methyl sulfate) (both ICI)

paraquat Common name paraquat (BSI, E-ISO, (m) F-ISO, ANSI, WSSA, JMAF); no name (Germany)
IUPAC name 1,1′-dimethyl-4,4′-bipyridinediium; 1,1′-dimethyl-4,4′-bipyridinium; 1,1′-dimethyl-4,4′-bipyridylium
Chemical Abstracts name 1,1′-dimethyl-4,4′-bipyridinium
CAS RN [4685-14-7] EEC no. 225-141-7

Physical Chamistry:
Composition Not normally isolated from the tech. products, which are >95% pure. Mol. wt. 257.2 M.f. C12H14Cl2N2 Form Colourless, hygroscopic crystals. M.p. Decomposes at c. 340 ºC V.p. <1 ´ 10-2 mPa (25 °C) KOW logP = -4.5 (20 °C) Henry <4 ´ 10-9 Pa m3 mol-1 (calc.) S.g./density 1.24-1.26 (20 ºC) Solubility In water c. 620 g/l (20 ºC). Practically insoluble in most organic solvents. Stability Stable in neutral and acidic media, but readily hydrolysed in alkaline media. Photochemically decomposed by u.v. irradiation in aqueous solution.