1. The herbicidal activity of certain quaternary salts of 2,2′-dipyridyl is the subject of U.K. Patent Specification 785,732 ; U.K. Patent Specifications 813,531 and 813,532 disclose similar activity in the quaternary salts of 4,4′-dipyridyl. The activity of 2,4′-dipyridyl salts has not hitherto been disclosed.
2. Michaelis, L., and Hill, E. S., J. Gen. Physiol., 16, 859 (1933).
3. Michaelis, L., and Hill, E. S., J. Amer. Chem. Soc., 55, 1491 (1933).
4. Brian, R. C., Homer, R. F., Stubbs, J., and Jones, R. L., Nature, 181, 446 (1958).
5. Krumholtz, P., J. Amer. Chem. Soc., 73, 3487, 4449 (1951).