Chlorpromazine-iodine reaction

Conductimetric Titrations and Spectrophotometric Study of the Chlorpromazine-Iodine Reaction... 

Chlorpromazine (33) can probably be considered the prototype of the phenothiazine major tranquilizers. The antipsychotic potential of the phenothiazines was in fact discovered in the course of research with this agent. It is of note that, despite the great number of alternate analogs now available to clinicians, the original agent still finds considerable use. The first recorded preparation of this compound relies on the sulfuration reaction. Thus, heating 3-chlorodiphenylamine (30) with sulfur and iodine affords the desired phenothiazine (31) as well as a lesser amount of the isomeric product (32) produced by reaction at the 2 position. The predominance of reaction at 6 is perhaps due to the sterically hindered nature of the 2 position. Alkylation with w-C3-chloropropyl)dimethylamine by means of sodium amide affords chlorpromazine (33). ... 

Chlorpromazine plus iodine is not a combination that is likely to occur in a pharmaceutical formulation nor is the interaction of any significance in therapeutics. The study of the reaction is of biological importance, however, because of the information provided with respect to the electronic properties of the phenothiazine derivatives, and these properties in turn are likely to have significance in understanding the underlying mechanisms of the drug. That is, CPZ-I2 is a model system. 

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