Confirmation of the presence of imine bonds in thermally cured polyimides

Abstract

SYNOPSISModel compounds for imines formed during the thermal curing of short chain polyimides have been synthesized and characterized. These compounds have imine bonds ( C = N ) formed by the nucleophilic attack of primary amines on imide carbonyls. The C = N stretching mode appears at 1649-1664 cm-' in the Raman and infrared spectra of these compounds and the band assigned to the carbonyl mode in an imide ring with an imine bond appears near 1740 cm-' . These compounds have been prepared and characterized to verify the conclusions of a previously reported study in which bands observed in thermally cured short chain polyimides a t 1656 and 1742 cm-' were assigned as the C=N and associated C =O modes, respectively. It has also been confirmed that the C = N stretching mode in the imide model compounds is inherently IR weak and can only be seen if the concentration of imine species is high. 0 1993 John Wiley & Sons, Inc.

Assessment of Feasibility of Maillard Reaction between Baclofen and Lactose by Liquid Chromatography and Tandem Mass Spectrometry, Application to Pre Formulation Studies

“…FTIR analysis confirmed the formation of imine in the heated mixtures. Similar imine bonds have been reported in Maillard-type reactions but it has never been used in pharmaceutical evaluation of the Maillard reaction (37,38). Developing the brown color development is a key factor of the Maillard reaction occurrence and is also in accordance with the modern techniques used in this study.…”

“…Later at 2006, Namli et al followed the reaction process between benzaldehyde or salicylaldehyde and or 2-pyridinecarboxaldehyde with aniline and showed that resulting imine, shows a band in FTIR spectra at about 1,630 cm −1 (36). Other scientists have reported imine formation using FTIR spectroscopy with similar absorption bands (37,38). In the baclofen FTIR spectrum, the absorption band at about 1618 cm −1 is consistent with baclofen N-H bending vibration (Fig.…”

The synthesis and characterization of polyimide homopolymers based on 5(6)-amino-1-(4-aminophenyl)-1,3,3-trimethylindane

“…These wavelengths correspond to previously reported imide ring adsorptions 43–46. Complete cyclization was also evident by the lack of amide CO (1640 cm −1 ) and NH (1550 cm −1 ) peaks 47, 48.…”

Friction and Wear Mechanisms of Sintered and Thermoplastic Polyimides under Adhesive Sliding

“…This side reaction could lead to branching and is promoted by a slight excess of basic groups and suppressed by a slight excess of acid groups. Saini et al [51] monitored amine terminated imide compounds by spectroscopy during heating. The appearance of a C --N absorption band confirmed that imide-imine conversion was occurring, which was predicted by a cross-link reaction mechanism involving the attack of terminal amino groups into imide carbonyl groups, with the resulting formation of imine.…”