- Stereoisomeric effects in thermo-remendable polymer networks based on diels-alder crosslink reactions
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This study describes the synthesis, the spectroscopic, and the thermal characterization of linear and crosslinked polymers as well as a number of corresponding model compounds, containing Diels-Alder adducts derived from furan and maleimide groups. The thermal reversibility (rDA, DA) of structurally varied model compounds, polymeric and network structures were studied by differential scanning calorimetry, where possible in combination with 1H NMR spectroscopy. It was established that the endo and exo DA stereoisomers show significantly different thermal responses: the rDA of the endo DA-adducts typically takes place at 20-40 K lower temperatures than that of the corresponding exo DA-adducts in all cases, with the exception of some aromatic maleimides. Although In situ isomerization was observed to a limited extent and only In some cases, this effect is not expected to influence the thermoremendability of DA-crosslinked networks being dependent on two separate stereoisomeric rDA steps.
- Canadell, Judit,Fischer, Hartmut,De With, Gijsbertus,Van Benthem, Rolf A. T. M.
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body text
p. 3456 - 3467
(2011/05/02)
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- A green chemical approach for the N-alkylation of aldoximes to form nitrones in organized aqueous media and their in situ cycloaddition with olefins
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Aldoximes react with α,β-unsaturated carbonyl and sulfonyl compounds in organized aqueous media (nanoreactor system) using dodecylbenzenesulfonic acid (DBSA) as surfactant to generate N-alkylated nitrones, which undergo intermolecular cycloaddition in the same pot with maleimides to give the desired cycloadduct in absence of any organic solvent and catalyst. Divinyl sulfone was successfully used for both N-alkylation and intramolecular cycloaddition, affording only one cycloadduct. This is a new example of green chemistry and provides a new aspect of reactions in water.
- Hota, Sandip K.,Chatterjee, Amrita,Bhattacharya, Pranab K.,Chattopadhyay, Partha
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supporting information; experimental part
p. 169 - 176
(2010/04/22)
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- Synthesis and antimicrobial activities of N-substituted imides
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In the field of our research programs concerning novel antimicrobial agents, a series of N-substituted imides was synthesized. These compounds were obtained by cyclization of amido-acids in acetic anhydride/sodium acetate or hexamethyldisilazane/zinc bromide for the hydroxy-aromatic derivatives. The hydroxy-alkyl maleimides were directly prepared by condensation of the corresponding amino-alcohol with maleic anhydride in boiling toluene. Most of N-substituted maleimides showed an interesting antimicrobial activity towards bacteria from the ATCC collection (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) but the MIC values for P. aeruginosa were always high (128 μg/ml). The imides with alkyl substituents showed higher activities than aromatic analogues with MIC values in the range of 8-32 μg/ml. Comparatively, succinimides were practically inactive.
- Zentz, Frederic,Valla, Alain,Le Guillou, Regis,Labia, Roger,Mathot, Anne-Gabrielle,Sirot, Danielle
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p. 421 - 426
(2007/10/03)
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- Process for preparation of N-substituted maleimides
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N-substituted maleimide represented by formula (2): STR1 is produced from N-substituted maleamic acid monoester represented by formula (1): STR2 in the presence of an acid catalyst by elmination of an alcohol from the monoester. The above N-substituted maleamic acid monoester represented by formula (1) is produced by esterification of N-substituted maleamic acid represented by formula (3): STR3 with an alcohol R2 -OH in the represence of an acid catalyst.
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- Novel Chromophoric Heterocycles Based on Maleimide and Naphthoquinone
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1-Phenyl-3,4-dichloromaleimide, 1-n-propyl-3-bromomaleimide, and 2,3-dichloro-1,4-naphthoquinone have been condensed with various mono- and bis-nucleophiles to yield a range of novel dyes and pigments.Their visible absorption spectra are discussed.
- Katritzky, Alan R.,Fan, Wei-Qiang,Li, Qiao-Ling,Bayyuk, Shibli
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p. 885 - 892
(2007/10/02)
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