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The study of the development of tannin-based adhesives from the African mahogany Khaya ivorensis A. Chev tannins condensed hexamine was carried out. Tannins from the bark, sapwood, and heartwood were extracted employing the industrial method (NaOH/Na2SO3/NaHSO3) and they were used to synthesize different formulations of biobased adhesives. Tannins/hexamine/water adhesives obtained were characterized by differential scanning analysis (DSC) to know their physical changes under heat action. Polymerization temperatures were between 90°C and 153°C. These adhesives heat resistance was studied by thermogravimetric analysis (TGA). Results showed good thermal stabilities properties for adhesives with degradation temperatures between 225°C and 250°C. Besides, a thermomechanical analysis (TMA) shows a high value of elasticity modulus for these adhesives. Finally, 2D HSQC NMR analysis was performed to confirm the good reactivity between African mahogany tannins and hexamine linked with strong bounds.

International audience; A complementary approach using Liquid Chromatographic-Mass Spectrometric analysis was proposed to characterize phenolic compounds from the methanol-water extracts of K. ivorensis A. Chev. Two High Performance Liquid Chromatography (HPLC) complementary methods were used for the determination of phenolic compounds from the bark, sapwood and heartwood of K. ivorensis. Methods employed involved direct analysis after filtration at 0.20 µm, using a RP C18 column and UV-VIS/ESI-FTMS detection. The methods used were different by their elution gradient and allowed analyzing the chemical composition of three parts of African mahogany extracts. In this study, 22 phenolic compounds and derivatives from K. ivorensis were separated, determined or tentatively characterized for the first time based on their methanol/water/formic acid extract mass spectra. The difference of gradients eluted various compounds, 8 were obtained with the first method and 14 with the second one. The main products were hydroxybenzoic acid and derivatives, resorcinol, esterified compounds, mannitol, quercetin and derivatives, dihydroxyflavan, and trihydroxyflavan.

International audience; The total phenolic and the condensed tannins content of the bark, the sapwood and the heartwood of Khaya ivorensis (K. ivorensis) from the natural forest of Gabon was investigated by Folin-Ciocalteu, vanillic assay and acid/butanol methods All these methods showed that the bark, the sapwood and the heartwood of K. ivorensis did not display a significant difference (p \textgreater 0.05) regarding their phenolic content and their condensed tannins content as well. The acetone/water extd. tannins from the bark were characterized by Matrix Assisted Laser Desorption/Ionization time of flight (MALDI-TOF) mass spectrometry and by Fourier Transform IR spectroscopy (FTIR). The presence of fisetinidin, gallocatechin, and trihydroxyflavan monomers was obsd. for the first time. Flavonoid oligomers linked to sugars were found within K. ivorensis condensed tannins. An heptamer formed by mixed fisetinidin, trihydroxyflavan, three dihydroxyflavans, and a carbohydrate dimer including mannose was also identified for the first time in the bark of K. ivorensis. That mahogany hardwood species did not exhibit any antifungal activity against the white rot fungus Coriolus versicolor. However, bark powder decreased the radial fungus growth.