Thianthrene-2,3,7,8-tetracarboxylic

It is not surprising that in attempted AICI3 catalysis of the reaction between thiophenol and various lactones, considerable amounts of thianthrene were obtained from a side reaction (81JOC5163). A low yield of thianthrene itself was obtained by converting o-bromobenzene thiol into its copper derivative (66JOC4071), but a good yield of thianthrene-2,3,7,8-tetracarboxylic acid 83 was observed from a hot reaction between 84 with cuprous oxide in DMF (82MI5). The saturated o-chlorobenzene thiols, 85... 

Poly(imide)s with the dithiathianthrene group are accessible from the reaction of thianthrene-2,3,7,8-tetracarboxylic dianhydride aromatic diam-ines. Thianthrene-2,3,7,8-tetracarboxylic dianhydride can be synthesized via a nucleophilic aromatic substitution of A-phenyl-4,5-dichloro-phthalimide with thiobenzamide, thioacetamide, and sodium sulfide. The polymers obtained have a good thermal stability in air and nitrogen. The polymers are amorphous and have been found to be soluble only in H2SO4. 

Thianthrene-2,3,7,8-tetracarboxylic anhydride polymerized with aromatic diamines by the conventional low temperature technique to yield soluble poly(amic acid)s. Polyimides were obtained by thermal cyclization of poly(amic add) films. Rigid diamines gave brittle films whereas 4,4 -oxydianiline and 4,4-methylene dianiline gave films that were creasable. The polyimides had excellent thermal stability in nitrogen and air and a moderate increase in solubility over the more linear and rigid analogs obtained firom pyromellitic dianhydride. 

Overall goals of our research in this area include synthesis of thianthrene di-, tri- and tetracarboxylic acid derivatives (10,11,12,13 Figure 7) starting with 3,4-dichlorobenzoic acid and 4,5-dichlorophthalic acid evaluation of their use in formation of thianthrene-containing polyimides, aramids, and polybenzoxazoles and... 

Thianthrene-di-, tri-, and tetracarboxylic acids, and a variety of their derivatives, were prepared and polymerized with co-monomers to obtain thianthiene-containing polyimides, aramids and polybenzoxazoles. The multiply substituted thianthrene derivatives were prepared starting with dichloro-substituted benzamide or phthalimide via chlorine displacement by sulfur nucleophiles. The protected carboxyl groups enhanced the displacement reaction to give thianthrene bisamides and imides in good yields. Deprotection with base gave carboxylic acid derivatives. 

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