On September 9, 1980, Chen, Min-Feng published a patent.Electric Literature of 52243-87-5 The title of the patent was 1,1′-Dialkyl-4,4′-bipyridinium dihalides and their herbicidal use. And the patent contained the following:
The title compounds I (R = alkyl, X = halogen) were prepared by treating 4,4′-bipyridine (II) with a haloalkanoic acid and H2O at pH <4. Thus II was treated with saturated aqueous ClCH2CO2H to give I (R = Me, X = Cl) in 99% yield. The experimental process involved the reaction of 1,1'-Dipropyl-[4,4'-bipyridine]-1,1'-diium bromide(cas: 52243-87-5).Electric Literature of 52243-87-5
The Article related to dialkylbipyridinium dihalide, bipyridinium dialkyl dihalide, Heterocyclic Compounds (One Hetero Atom): Pyridines and other aspects.Electric Literature of 52243-87-5