Editing Phenothiazine (section)

== Structure and synthesis==
The central C<sub>4</sub>SN ring is folded in phenothiazines.<ref>{{cite journal|title=The crystal and molecular structure of phenothiazine
|author=J. J. H. McDowell |doi=10.1107/S0567740876002215|journal=Acta Crystallographica Section B |volume=32|year=1976|issue=1 |page=5|bibcode=1976AcCrB..32....5M }}
</ref>

The compound was originally prepared by Bernthsen in 1883 via the reaction of [[diphenylamine]] with sulfur, but more recent syntheses rely on the cyclization of 2-substituted diphenyl sulfides. Few pharmaceutically significant phenothiazines are prepared from phenothiazine,<ref>Gérard Taurand, "Phenothiazine and Derivatives" in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim, 2005.{{doi|10.1002/14356007.a19_387}}</ref> although some of them are.<ref>T. Kahl, K.-W. Schröder, F. R. Lawrence, W. J. Marshall, Hartmut Höke, Rudolf Jäckh, "Aniline" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2005, Wiley-VCH: Weinheim.</ref>

Phenothiazines are electron donors, forming charge-transfer salts with many acceptors.