2657-15-0Relevant academic research and scientific papers
Synthesis of asymmetric tetracarboxylic acids and dianhydrides
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Page/Page column 14-15, (2008/12/05)
This invention relates to the compositions and processes for preparing 2,3,3′,4′-tetramethylbenzophenone and asymmetrical dianhydrides such as 2,3,3′,4′ benzophenone dianhydride (a-BTDA), and 3,4′-(hexafluoroisopropylidene)diphthalic anhydride (a-6FDA). a-BTDA is prepared by Suzuki coupling with catalysts from a mixed anhydride of 3,4-dimethylbenzoic acid and 2,3-dimethylbenzoic acid with a respective 2,3-dimethylphenylboronic acid and 3,4-dimethyl phenylboronic acid to form 2,3,3′,4′-tetramethylbenzophenone which is oxidized to 2,3,3′,4′-benzophenonetetracarboxylic acid followed by cyclodehydration to obtain a-BTDA. The a-6FDA was prepared by nucleophilic trifluoromethylation of 2,3,3′,4′-tetramethylbenzophenone with trifluoromethyltrimethylsilane to form 3,4′-(trifluoromethylmethanol) bis(o-xylene) which is converted to 3,4′-(hexafluoroisopropylidene-bis(o-xylene). The 3,4′-(hexafluoroisopropylidene)-bis(o-xylene) is oxidized to the corresponding tetraacid followed by cyclodehydration to yield a-6FDA.
