9-Thioxanthone

Ullmann condensation of the sodium salt of p-chlorothiophe-nol (31) with 2-iodobenzoic (32) acid gives 33. Cyclization by means of sulfuric acid affords the thioxanthone, 34. Reaction with the Grignard reagent from 3-dimethylaminopropyl chloride affords the tertiary carbinol (35). Dehydration by means of acetic anhydride affords chlorprothixene as a mixture of geometric isomers, 36. (Subsequent work showed the Z isomer-chlorine and amine on the same side—to be the more potent compound.) Chlorprothixene is said to cause less sedation than the phenothiazines. ... 

Alkylated sulfonamide groups have proven useful additions to the phenothiazine nucleus. The same seems to hold true in the thioxanthene series. Chlorosulfonation of the benzoic acid, 38, followed by displacement with dimethylamine affords the sulfonamide, 39. This is then taken on to the substituted thioxanthone (41) by the sequence of steps shown above Grignard condensation followed by dehydration gives thiothixine (42). 

It is by now apparent that the nature of the aryl group in the aryl acetic and aryl propionic acid antiinflammatory agents can be varied quite widely without loss of activity. The corresponding derivatives of homologous xanthones and thioxanthones thus both show activity as nonsteroid antiinflammatory agents. 

The thioxanthene ligand is oxidized to thioxanthone and sulfone ligands, the ratio of which depends on the amount of KMn04 Eq. (37) ... 

Table 3 presents the hyperfme splitting constants of some sulfur-containing aromatic radical anions. The series studied included the monoxides and dioxides of dibenzothio-phene 1, thioxanthene 2, thioxanthone 3, dibenzo[b,/] thiepin 4 and dithienothiophene dioxide 5. 

Thioxanthone S-oxidec Thioxanthone S,S-dioxidec Dibenz[h,/]thiepin Dibenz[h,/]thiepin S-oxide Dibenz[6,/]thiepin S, S-dioxide Dithienothiophene 7,7-dioxide... 

TABLE 4. Hyperfine splitting constants (gauss) of thioxanthone S-(mono or dijoxide radical anions as free or tight contact ion-pair ... 

TABLE 5. Reduction potentials (volt) of thioxanthone (TOS) and its oxides (TOSO, T0S02) compared with that of fluorenone (FIO)... 

Friedel-Crafts cyclization of that sulfide by means of sulfuric acid gives the desired thioxanthone... 

The presence of a rather more complex substituent on the remote piperazine nitrogen atom is consistent with tranquilizing activity. The preparation of one such agent, 16, begins with reaction of thioxanthone 11 (obtained by a sequence analogous to that used to... 

Figure 6.10. Rate constants for quenching of sensitizers by cis- and trans-stilbenes (open and filled circles, respectively). Sensitizers are as follows (1) tri-phenylene, (2) thioxanthone, (3) phenanthrene, (4) 2-acetonaphthone, (3) 1-naphthyl phenyl ketone, (6) crysene, (7) fluorenone, (8) 1,2,5,6-dibenzanthracene, (9) benzil, (10) 1,2,3,4-dibenzanthracene, (11) pyrene, (12) 1,2-benzanthracene, (13) benzanthrone, (14) 3-acetyl pyrene, (15) acridine, (16) 9,10-dimethyl-l,2-benzanthracene, (17) anthracene, (18) 3,4-benzpyrene.<57> Reprinted by permission of the American Chemical Society.

As with 2-cyclopentenone, the ratio (70) (71) varies with the molar concentration of the enone, the head-to-head dimer (71) becoming increasingly important at higher concentrations/133 This reaction is efficiently sensitized by acetophenone, benzophenone, thioxanthone, and naphthalene. The same enone concentration effect was observed in the sensitized photo-dimerization as in the direct photolysis. Similarly, quenching of the dimerization by piperylene was not accompanied by a change in dimer ratio. Systematic... 

Isopropyl thioxanthone/Ethyl diethanol amine 1 80 All Removed... 

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