Chemical Constitution and Activity of Bipyridylium Herbicides. XII. Diquaternary Salts of 6-Methyl-2,2'-bipyridyl and 2-Methyl-4,4'-bipyridyl

Abstract

6-Methyl- and 6-ethyl-2,2?-bipyridyl and 2-methyl-4,4?-bipyridyl have been prepared by reaction of the appropriate alkyllithiums with 2,2?- and 4,4?-bipyridyl. The alkylbipyridyls have been converted into diquaternary salts related to the herbicides diquat and paraquat. Two of the salts, 4-methyl-6,7-dihydrodipyrido[1,2-a:2?,1?-c]pyrazinediium dibromide and 1,1?,2-trimethyl-4,4?-bipyridinediiumdibromide, are about as active as post-emergent herbicides as diquat and paraquat.