Recent Advances in the Chemistry of Phenothiazines

This chapter discusses the chemistry of phenothiazines— that is, preparation of phenothiazines via ring closure, molecular structure and physical properties, free radicals, cations, and charge-transfer complexes within the phenothiazine class, ring substitution reactions of phenothiazines, and metabolism of phenothiazines. The name “phenothiazine” and the numbering given in the Revised Ring Index, used in Chemical Abstracts, and recommended by the lUPAC Rules of Organic Nomenclature is be used throughout this chapter. The 0- and p-quinonoid forms of phenothiazine— namely, 1H-, 3H-, and 4aH-phenothiazine are represented only by 3H-phenothiazines, in which both the hydrogen atoms are substituted. The cation obtained on two-electron oxidation of phenothiazine is referred to as the phenazathionium cation.