representative suitable organic anions are carboxylate r coo amide rcon h 2 r alkoxide r 3 co or etherate ro suitable alkali or alkaline earth metals are lithium li sodium na potassium k cesium cs magnesium mg calcium ca preferably sodium or potassium and most preferably sodium the synthesis of the diquat 7 salt is conducted with a continuous stirring at a temperature of about 50 u00b0 c to about 80 u00b0 c preferably about 60 u00b0 c to about 80 u00b0 c at autogenous pressure in a suitable non aqueous solvent such as alcohol e g ethanol toluene or tetrahydrofuran until crystals of the diquat 7 salt are formed usually for about 4 to about 24 hours the crystals of the product settle to the bottom the reaction mixture is cooled e g in a water ice bath and the product is separated from the reaction mixture by any suitable means e g by filtration the crystals are then washed with a suitable solvent e g absolute ethanol followed by a wash with an anhydrous diethyl ether the diquat 7 salt crystals are then dried the hydroxide form of diquat 7 may be obtained in any conventional manner from the salt of diquat 7 such as by ion exchanging the salt of diquat 7 with a suitable hydroxide in any conventional manner e g in an ion exchange column any of the.