Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1986-09-02
1987-09-15
Raymond, Richard L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D30789
Patent
active
046940898
ABSTRACT:
A process for preparing pyromellitic dianhydride by dehydration of pyromellitic acid is disclosed. The dehydration is conducted in solid state by indirect heating. The characteristic feature of the process is that when the most part of pyromellitic acid was converted to the dianhydride, the remaining pyromellitic acid is dehydrated while regulating the temperature of the heating medium between 200.degree. C. and 235.degree. C. By this process, pyromellitic dianhydride with excellent quality, good color and free flowing property can be obtained easily, smoothly, and rapidly. A very simple apparatus can be used in the process and the apparatus can be constructed from cheap materials.
REFERENCES:
patent: 2937189 (1960-05-01), Hoffman
Kosaka Tsuneo
Sakai Yukio
Mitsubishi Gas Chemical Company Inc.
Raymond Richard L.
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