The Elusive Antiaromaticity of Maleimides and Maleic Anhydride: Enthalpies of Formation of N-Methylmaleimide, N-Methylsuccinimide, N-Methylphthalimide, and N-Benzoyl-N-methylbenzamide.
In order to understand the antiaromaticity of maleimides, the enthalpies of formation and sublimation of N-methylmaleimide, N-methylsuccinimide, N-methylphthalimide, and N-benzoyl-N-methylbenzamide were measured. The numerical values of enthalpies of formation for these compounds in the solid state are -329.3 +/- 1.4, -469.8 +/- 1.6, -325.0 +/- 2.1, and -239.6 +/- 3.8 kJ mol(-)(1), respectively, while the corresponding values in the gaseous state are -256.0 +/- 1.5, -389.7 +/- 1.6, -233.9 +/- 2.2, and -119.5 +/- 3.8 kJ mol(-)(1), respectively. The values of enthalpies of sublimation for the same compounds are 73.3 +/- 0.5, 80.1 +/- 0.3, 91.1 +/- 0.5, and 120.1 +/- 0.4 kJ mol(-)(1), respectively. We find that the antiaromaticity of maleimides is only modest.
Roux
María Victoria
MV
Institute of Physical Chemistry "Rocasolano", CSIC, Serrano 119, 28006 Madrid, Spain, and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250.
Jiménez
Pilar
P
Martín-Luengo MÁ
Maria Ángeles
Dávalos
Juan Z.
JZ
Sun
Zhiyuan
Z
Hosmane
Ramachandra S.
RS
Liebman
Joel F.
JF