Effect of catalytic conditions on the synthesis of new aconitate esters

Sugar cane is a crop which generates large amounts of biomass and a juice rich in highvalue natural molecules. After extracting sugar from the juice, the recovering of various compounds such as organic acids contained in molasses could contribute to increase the competivity of the sugar industry. Therefore, according to the biorefinery approach, we propose to study the chemical conversion of one of these acids, the aconitic acid, by esterification reactions. A new series of aconitate esters have been synthesized by combining aconitic acid and alcohols from natural origin. The effects of experimental conditions have been investigated and have shown that the type of catalysis has a significant effect on the selectivity. Kinectics have thus been performed to determine the best conditions to synthetize enriched compositions in esters. Homogeneous catalysis generates the highest yield in triester. Heterogeneous catalysis(macroporous resins) is prefered for the production of monoesters while catalysis assisted by ionic liquid is adapted to prepare mainly diesters. Green indicators have been discussed according to the calculations performed. The resulting polyfunctional esters are totally biosourced molecules and have a great potential as bioproducts for different applications

Valorisation de la bagasse de canne à sucre (chimie, photochimie et élaboration de panneaux et composites)

Une méthode originale de la modification des fibres de bagasse de canne à sucre est présentée. Elle consiste en l'oxydation au periodate de sodium ou au bioxyde de chlore des groupes hydroxyle phénoliques de la lignine pour l'obtention de quinones suivie du greffage en surface de l'alcool furfurylique. Des matériaux originaux, composites (18 % de fibres et 82 % de résine) et panneaux (90 % de fibres et 10 % de résine) avec une résine phénolique ou lignophénolique ont été élaborés. Parallèlement, une étude photochimique sur des fibres de bagasse a éte entreprise. Cette étude s'est poursuivie à un niveau moléculaire sur de la lignine extraite de bagasse ainsi que sur un modèle dibenzodioxocine de lignine, groupement récemment identifié dans les lignines.An original method of modification of sugar cane bagasse fibres is presented. It consists in the oxidation with sodium periodate or with chlore dioxyde of the phenolic hydroxyl groups of the lignin so as to obtain quinones before the grafting of furfuryl alcohol at the surface. Original materials, composites (18 % fibres and 82 % resin) and panels (90 % fibres and 10 % resin) with a phenolic or lignophenolic resin were realized. At the same time, a photochemical study was undertaken on bagasse fibres. This photochemical study was carried out at a molecular level on lignin extracted from some bagasse and on a dibenzodioxocine model of lignin, a group recently identified in lignins.BORDEAUX1-BU Sciences-Talence (335222101) / SudocSAINT DENIS/REUNION-Droit Lettre (974112101) / SudocSudocFranceReunionFRR

Heterogeneous catalytic valorization of aconitic acid produced form sugar cane

+CDFA+WHN:MET:LMA:LCH:NESInternational audienceNon

Cassava mosaic disease in Madagascar: complex epidemiology and evolutionary dynamics of cassava mosaic geminiviruses

International audienceBACKGROUND and OBJECTIVES Cassava is the staple food for hundreds of millions of people in Africa but its cultivation is seriously constrained by cassava mosaic disease (CMD) in Madagascar and in Africa in general. We have undertaken (1) to identify the cassava mosaic geminiviruses (CMGs) involved in CMD in Madagascar and their epidemiological characteristics from country-wide surveys, and (2) to study the genetic and spatial structure of Malagasy CMGs populations. MATERIAL and METHODS Altogether 708 cassava leaf samples were collected with and without CMD symptoms from the main cassavagrowing areas of Madagascar during 2009 to 2011. Prevalence and symptom severity of CMD, origin of infection (whitefly or cutting), and abundance of whiteflies were assessed. RESULTS Molecular diagnosis of CMGs in Madagascar revealed an unprecedented diversity and co-occurrence of six CMGs. Distinct geographical distributions were observed for the six viruses. While EACMCV and SACMV were widespread, ACMV was more prevalent in the central highlands, and EACMV and EACMKV were prevalent in lowlands and coastal regions. PCR diagnosis revealed that mixed infection (up to four co-infected viruses) occurred in 21% of the samples and were associated with higher symptom severity scores. Pairwise comparisons of virus associations showed that EACMCV was found in mixed infections more often than expected while ACMV and SACMV were mostly found in single infections. Even if the whitefly vector Bemisia tabaci was more abundant in lowland and coastal areas, infected cuttings remain the primary source of CMD propagation (95%) in Madagascar. SACMV and ACMV, the two most prevalent viruses, displayed low degrees of genetic diversity and have most likely been introduced to the island only once. By contrast, EACMV-like CMG populations (EACMV, EAMCKV, EACMCV and complex recombinants of these) were more diverse, more spatially structured, and displayed evidence of at least three independent introductions from mainland Africa. CONCLUSIONS Our study highlights both the complexity of CMD in Madagascar, and the distinct evolutionary and spatial dynamics of the different viral species that collectively are associated with this disease. (Résumé d'auteur