The Synthesis of N-Substituted Isomaleimides

Abstract

Reaction of terephthalamie acid with ethyl chloroformate and triethylamine. A solution of terephthalamie acid (1.4 g., 0.0085 mole) and triethylamine (1.72 g., 0.017 mole) in 20 ml. of dichloromethane was cooled to 0-6°and 1.9 g. (0.018 mole) of ethyl chloroformate was added. Stirring was continued for 3.5 hr. at room temperature after the addition. The mixture was filtered to remove triethylamine hydrochloride and the solvent was removed under reduced pressure. The residue was washed several times with ether. The ether-insoluble material (1.4 g.) melted at 140-155°. The ether-soluble material (0.2 g.) melted with decomposition at 90-95°. The infrared spectra and melting points of these products preclude the presence of more than a trace of ethyl p-cyanobenzoate which has a reported melting point of 50°."Mixed anhydride of benzoic and ethylcarbonic acids prepared in presence of ethanol. A stirred solution of 12.2 g. (0.1 mole) of benzoic acid, 4.6 g. (0.1 mole) of ethanol and 10.1 g. (0.1 mole) of triethylamine in 100 ml. of dichloromethane was stirred at 0°while ethyl chloroformate (10.8 g., 0.1 mole) was added dropwise over 30 min. The temperature was kept below 0°d uring the addition. After the addition the external cooling bath was removed and the reaction mixture was stirred for 3 hr. The mixture was filtered and the filtrate washed with water, 5% sodium carbonate solution, water and dried over magnesium sulfate. The drying agent was removed by filtration and the solvent removed under reduced pressure. The clear, colorless liquid which remained, n" 1.4930, showed absorption in the carbonyl region of its infrared spectrum (liquid film) at 1775 cm.-1 (s) and 1715 cm.-1 (w). The spectrum was identical with that for the (25) K. H. Slotta and R. Kethur, Ber., 71, 335 (1938). mixed anhydride of benzoic and ethyl carbonic acids (n" 1.4941) obtained by the procedure described above11 except that no ethanol was added and the reaction time was 1 hr. An attempt was made to distill the crude product in a semimicro distilling apparatus. A vacuum of 1 mm. was applied and the distillation pot heated slowly. Nothing distilled until the temperature of the pot reached 140°; then the pressure rose to 4 mm. and vigorous decomposition of the product began.Dehydration of benzamide with ethyl chloroformate and triethylamine. A solution of 2.8 g. (0.023 mole) of benzamide in 25 ml. of acetone and 2.3 g. (0.023 mole) of triethylamine was cooled to 0-5°. Ethyl chloroformate (2.5 g., 0.023 mole) was added dropwise with stirring. After the addition, the cooling bath was removed and the reaction was stirred at room temperature for 3 hr. The reaction mixture was diluted with water and extracted three times with dichloromethane. The dichloromethane extracts were dried over magnesium sulfate and solvent was removed under vacuum. An infrared spectra of the solid residue (2.4 g.) indicated traces of benzonitrile. The residue was washed with ether which left a white solid (2.0 g.), m.p. 119-121.5". Recrystallization from aqueous ethanol raise...

Asymmetric Oligomerization of N-Substituted Isomaleimide

“…Six RIMI were prepared from maleic anhydride and the corresponding primary amines, according to the method by Cotter et al 5 Boiling points and melting points of RIMI are as follows: nBIMI bp 96°Cj6 mmHg, iBIMI bp 97°Cjl7mmHg, tBIMI bp 32-36°Cj5.0 x 10-2 mmHg, CHIMI bp 76--79°Cj5.0x 10-2 mmHg; mp 35-37°C, PhiMI mp 62-63°C, and MBZIMI bp 112-ll4°Cj5.0x 10-2 mmHg. RIMI monomers were identified by IR and NMR spectra.…”

Anionic Polymerizations of N-Substituted Isomaleimide

“…12 types of RIMI were synthesized according to the method by Cotter et al, 13 as shown in Scheme 1. N-Substituted maleamic acid CHCO,11 o + CHCO,,, the results of elemental analysis, IR and 1 H NMR spectra.…”

Synthesis and Characterization of Newer Homopolymaleamides and Copolymaleamides from N,N′-Methanedianiline-bisisomaleimide and Aliphatic Diamines

“…This methane dianilinebismaleamic acid (0.05 mol) was treated with DCC (0.1 mol) in dichloromethane and an ether mixture. 13 The precipitated dicyclohexylurea was filtered off and the product MBIMI was recovered from the filtrate by removing the solvent under reduced pressure. MBIMI, after recrystallization from benzene-ether, melted at 155oC.…”