Preparation from carbonaceous material: M.
Kiebler, US2461740 (1949 to Carnegie Inst. of Tech.); Germain et al.,Bull.
Soc. Chim. Fr.1962, 779; from tetrahalophthalic acid: Brusset,
Uny, ibid.1951, 565; Juettner, US3067246 (1962).
Properties
Crystals. mp 286-288° in sealed tube with decompn. Freely sol in
water or alcohol; sol in boiling concd H2SO4 without decompn.