Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1998-03-02
1999-10-26
Richter, Johann
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
549262, 562595, C07D207448, C07D30760, C07C 5703
Patent
active
059731664
ABSTRACT:
In accordance with the present invention, there are provided improved methods for the preparation of maleimide monomers. This new method for the synthesis of maleimides is clearly superior to those documented in the prior art. Furthermore, the invention method utilizes materials with reduced toxicity, thus the overall process has a minimal impact on the environment. Thus, in accordance with the present invention, it has been discovered that certain amine salts can be successfully used to replace the polar, aprotic solvents cited in the prior art for the cyclodehydration of maleamic acids. The use of these salts provides competitive reaction times and product yields relative to results obtained with the polar, aprotic solvents. These salts have the advantage of having no vapor pressure and, therefore, have no possibility to co-distill with the water produced by the cyclodehydration reaction. Furthermore, such salts can be tailored to have desirable solubility characteristics (i.e., soluble in the refluxing azeotropic solvent, but insoluble at room temperature) that permit their easy removal from the reaction product. Such salts are not destroyed during the cyclodehydration reaction and, therefore, can be efficiently recycled again and again.
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Kita et al., Journal of Applied Polymer Science, 63(3), pp. 363-368, Jan. 1997.
Coleman et al., "Reaction of Primary Aliphatic Amines with Maleic Anhydride" Journal of Organic Chemistry, 24:135 (1959).
Kita et al., The Chemical Society of Japan 12:971-976 (1995).
Dershem Stephen M.
Mizori Farhad G.
Keating Dominic
Reiter Stephen E.
Richter Johann
The Dexter Corporation
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