Method of preparation of maleimides by thermal cyclization...

Details Method of preparation of maleimides by thermal cyclization... Method of preparation of maleimides by thermal cyclization...

2005-12-15

2009-11-24

Shameem, Golam M. M. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C548S549000, C562S595000

Reexamination Certificate

active

07622597

ABSTRACT:
Method of preparation of maleimides by thermal cyclization of maleamic acids in the presence of a catalyst consists in that reaction of a substituted maleic anhydride with a primary amine is performed in an organic solvent in the presence of betaine at a temperature of 100 to 180° C., at a ratio of the primary amine to the substituted maleic anhydride of 0.6:1.6. Maleimides, obtained in this way, are further purified by extraction, and finally, they are crystallized. As a catalyst, there may be also used betaine in a mixture with inorganic and organic acids, or betaine may be deposited on a solid carrier, or possibly, betaine may be deposited on a carrier in combination with inorganic acids.

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