4,4′-Bipyridine (abbreviated to 4,4′-bipyor4,4′-bpy) is an organic compound with the formula (C5H4N)2. It is one of several isomers of bipyridine. It is a colorless solid that is soluble in organic solvents. is mainly used as a precursor to N,N′-dimethyl-4,4′-bipyridinium [(C5H4NCH3)2]2+, known as paraquat.
4,4′-Bipyridine was first obtained in 1868 by the Scottish chemist Thomas Anderson via heating pyridine with sodium metal.[1] However, Anderson's empirical formula for 4,4′-bipyridine was incorrect.[2] The correct empirical formula, and the correct molecular structure, for 4,4′-bipyridine was provided in 1882 by the Austrian chemist Hugo Weidel and his student M. Russo.[3]
4,4'-Bipyridine is an intermediate in the production of paraquat, a widely-used herbicide. In this process, pyridine is oxidized to 4,4'-bipyridine in a coupling reaction, followed by dimethylation to form paraquat.[4]
The reducing agent is N,N'-bis(trimethylsilyl)-4,4'-bipyridinylidene is produced by reduction of 4,4'-bipyridine in the presence of trimethylsilyl chloride (Me = CH3):
See also: Fehling, Hermann Christian von, ed. (1890). Neues Handwörterbuch der Chemie [New Concise Dictionary of Chemistry] (in German). Vol. 5. Braunschweig, Germany: Friedrich Vieweg und Sohn. p. 974. See γ-Dipyridyl.
^Anderson gave the empirical formula for 4,4′-bipyridine as C10H10N2. See:
(Anderson, 1868), p. 209.
(Fehling, 1890), p. 974 (γ-Dipyridyl).
^Weidel, H.; Russo, M. (1882). "Studien über das Pyridin" [Studies of pyridine]. Monatshefte für Chemie (in German). 3: 850–885. doi:10.1007/BF01516855. S2CID97065714. The empirical formula for 4,4′-bipyridine (γ-Dipyridyl) appears on p. 856 ; the molecular structure of 4,4′-bipyridine (γ-Dipyridyl) appears on p. 867.
^Tsurugi, Hayato; Mashima, Kazushi (2019). "Salt-Free Reduction of Transition Metal Complexes by Bis(trimethylsilyl)cyclohexadiene, -dihydropyrazine, and -4,4′-bipyridinylidene Derivatives". Accounts of Chemical Research. 52 (3): 769–779. doi:10.1021/acs.accounts.8b00638. PMID30794373. S2CID73505603.
^Biradha, K.; Sarkar, M.; Rajput, L. (2006). "Crystal engineering of coordination polymers using 4,4′-bipyridine as a bond between transition metal atoms". Chemical Communications (40): 4169–79. doi:10.1039/B606184B. PMID17031423.
