PURPOSE: To provide novel aromatic tetracarboxylic acids and derivatives thereof which are suitable in preparing polyimides to be used as protective films and photographic relief duplicates.
CONSTITUTION: Novel aromatic tetracarboxylic acids and derivatives thereof are represented by formula I {wherein Z" is one of groups of formulae II-IV; free bonds are linked with each other at the ortho-position; Y'' is a direct bond, CH2, CH2-CH2, O, S, SO, SO2, NR or CRR1 [wherein R is H, 1-10C alkyl, phenyl, naphtyl or phenyl-CaH2a (wherein (a) is 1-4); and R1 is R excluding H]; R0 is 1-12C alkyl a halogen, CN, NO2, 1-12C alkoxy, phenoxy, naphthoxy or phenyl-CaH2a; and n' is 0-3} and include, e.g. xanthenetetracarboxylic acid clianhydride. Of these compounds, xanthenetetracarboxylic acid can be obtained by treating 3,3',4,4'-tetra-methylbiphenyl ether with CCl4 in the presence of AlCl3, then hydrolyzing the resulting product with diluted hydrochloric acid and oxidizing the resulting 2,3,6,7-tetramethylxanthone.
RUDORUFU DOUTOHAARAA
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