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.

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.

Abstract: Aliphatic amines are obtained by continuous addition of ammonia to C2- to C8-alkenes in the presence of a heterogeneous or homogeneous catalyst at a pressure of 2 to 8 MPa, a temperature of 220 to 320° C. and a molar ratio of ammonia to the alkene of 1.5 to 20, while the gaseous reaction mixture which leaves the second section, is cooled to a temperature near the dew point, it is led to the enrichment part of the first section, where it is sprayed in counterflow with a liquid mixture consisting of the starting substances. The unreacted starting substances thus disposed of the most of the amine formed are recycled under pressure in gaseous state to the second section, the liquid mixture in the impoverishment part of the section gets rid of the unreacted starting substances, and from the bottom of the first section the concentrate is conducted to further processing.