System to isolate dianhydrides

Distillation: apparatus – Apparatus – Systems

Reexamination Certificate

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C202S172000, C202S186000, C202S236000, C159S002100, C159S006200, C159S013200, C159S901000

Reexamination Certificate

active

07153394

ABSTRACT:
A process to isolate dianhydride from an exchange reaction comprises extracting a bisimide/anhydride exchange reaction aqueous phase with an organic solution comprising an exchange catalyst at a first temperature and pressure to form an extracted aqueous phase comprising water, exchange catalyst and a dianhydride precursor; removing water from the extracted aqueous phase at a second temperature and pressure to form a molten phase, wherein the second pressure is less than the first pressure; removing water and exchange catalyst from the molten phase at a third temperature and pressure to form an isolation mixture; and converting the dianhydride precursor in the isolation mixture to dianhydride at a fourth temperature and pressure, wherein the fourth temperature is greater than the second and third temperatures and the fourth pressure is less than the second and third pressures.

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DE 3213166. Publication Date Oct. 13, 1983. Abstract Only (1 page).
European Search Report Dated Aug. 6, 2003.

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