ABSTRACT
Bipyridiliums Sunlight and UV light degrade paraquat dichloride (1,1 -dimethyi-4,4-bipyridil ium dichloride), first by demethylation followed by ring cleavage of one of the heterocyclic rings to form 4-carboxy-l-methylpyridinium ion and methylamine. Paraquat can be photodegraded from desiccated leaf surfaces and possibly to the extent of 25-50% in 3 w k under bright sunlight.
