... 2,3,5-BenzenetetracarboxylicAnhydride;1H,3H-Benzo[1,2-c:4,5-c']difuran- 1,3,5,7-tetrone;DerivationAppearanceWhite to light ... conditionsPmda content98.5% minAcid value1015min ( mg KOH/g)Melting point284 °C minParticle size90% min ( 150µm)Packing25kgs in Fiber Drum * ... needle shape, with density 1.68g/cm3,melting point 285°C--288°C,neutralization equivalent 54.5±0.2 , and easy to sublimate ...