Photoredox reactions applied to the valorisation of carbon monoxide and 1,3-butadiene

Le domaine de la photocatalyse connait un intérêt important car il permet le développement de procédés éco-compatibles et l’emploi de conditions douces. De nombreux photocatalyseurs organiques ou organométalliques tels que les xanthènes, les complexes de ruthénium ou d’iridium ont été développés. A ce jour, très peu d’exemples décrivent la valorisation de gaz tels que le monoxyde de carbone et le 1,3-butadiène dans des réactions de catalyse photorédox. Dans ce contexte, les travaux présentés dans la thèse ont reporté la synthèse d’acides arylcarboxyliques et la fonctionnalisation en α d’aldéhydes photocatalysées respectivement par le ruthénium tris(bipyridine) et l’éosine Y, sous pression de monoxyde de carbone. La valorisation du 1,3-butadiène est également décrite par arylation de Meerwein à partir de sels d’aryldiazonium, associée à la réaction de Ritter photocatalysée par le ruthénium tris(bipyridine). L’arylation de Meerwein a également été associée à d’autres nucléophiles tels que les isonitriles, de même qu’à des étapes de cyclisation pour les synthèses de dihydroisoquinoléines et d’isochromanones. Enfin, la synthèse de phtalides par cyclisation intramoléculaire et photocatalysée par le 4CzIPN a été effectuée.Photocatalysis field is of great interest because it allows development of eco-friendly processes and use of mild conditions. Many organic and organometallic photocatalysts, such as xanthenes, as well as ruthenium and iridium complexes were then developed. To date, very few examples describe recovery of gases such as carbon monoxide and butadiene by photoredox catalysis. Therefore, the work presented in this thesis has reported synthesis of arylcarboxylic acids and fonctionalisation in position α of aldehydes, photocatalysed respectively by ruthenium tris(bipyridine) and eosin Y, under pressure of carbon monoxide. Valorisation of butadiene has also been described using Meerwein arylation from aryl diazonium salts, associated with Ritter reaction, photocatalysed by ruthenium tris(bipyridine). Meerwein arylation has also been conjugated to nucleophiles other than nitriles, as well as cyclisation steps for dihydroisoquinoleines and isochromanones synthesis. Finally, phtalides synthesis was carried out by intramolecular cyclisation, photocatalysed by 4CzIPN

Développement de nouvelles synthèses photocatalysées

National audienc

Visible-Light-Mediated Hydroxycarbonylation of Diazonium Salts

International audienceA visible light‐promoted catalytic photoredox hydroxycarbonylation was achieved on aryl diazonium salts whether preformed or generated in situ from the corresponding anilines. This strategy allows a straightforward access to a variety of carboxylic acids under mild conditions

Photocatalyzed Synthesis of 3-Substituted Phthalides: A Key Access to (+/-)-Herbaric Acid

International audienceAn efficient organophotocatalyzed protocol was developed for the preparation of 3-substituted phthalides. The presented transformation was performed under particularly mild conditions within 6 h and was ultimately applied to a precursor of the herbaric acid

Multi-platform observations of a representative springtime case of Bodélé and Sudan dust emission, transport and scavenging over West Africa

26-30 november

A new series of trivalent lanthanide (Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) coordination polymers with a 1,2-cyclohexanedicarboxylate ligand: synthesis, crystal structure, luminescence and catalytic properties

International audienc

Detection of hepatitis C virus antibodies and RNA among medicolegal autopsy cases in Northern France

International audienceForensic medical personnel are at risk of exposure to blood-borne viruses including hepatitis C virus (HCV). The aim of this study was to determine prevalence of HCV markers among a cadaver population at the medicolegal institute in Lille. Seventy-seven consecutive cadavers were screened for antibodies to HCV and for HCV RNA. Positive results were confirmed by an immunoblot assay. Fifty-three cadavers had a histopathologic study. Anti-HCV was detected in 13 (16.9%) and accompanied by HCV RNA in 7 (9%) cases. The rate of HCV RNA detection among seropositive cases was 53.8%. Five cases had histopathologic lesions suggestive of hepatitis. This is the first HCV RNA screening in forensic cadavers. The results highlight the high prevalence rate of HCV cases in medicolegal practice in Lille. All forensic specimens should be treated as potentially infectious and universal precautions should be taken

Multi-platform observations of a springtime case of Bodele and Sudan dust emission, transport and scavenging over West Africa

The structure of the Saharan air layer over Niger and Benin during a major springtime dust event from the Bodele region and Sudan is investigated using airborne lidar and dropsonde measurements. Aircraft operations were conducted on 13 and 14 June 2006, within the framework of the African Monsoon Multidisciplinary Analysis Special Observing Period. Complementary ground-based and satellite observations, as well as European Centre for Medium-range Weather Forecasts analyses are used to investigate the regional aspects of emission, transport and deposition in the period from 9 to 14 June 2006, to provide a framework for the interpretation of the airborne measurements. The study details the transport patterns of dust from eastern Saharan sources towards the southwest in the springtime, and highlights the role of the intertropical discontinuity and the Darfur mountains in injecting the aerosols from Bodele and Sudan, respectively, over the monsoon flow, and in the African easterly jet (AEJ) region. It also illustrates the impact of the daily variability of the emissions in the source regions on the dust load advected westward by the AEJ and observed over Benin. The impact of a mesoscale convective system (MCS) on the dust load and vertical distribution observed over Benin and southern Niger was also investigated, nearly 12 hours after its passage over Benin. The only discernible impact on the dust distribution is observed to be associated with widespread subsidence in the wake of the MCS, over northern Benin and Niger. Wet scavenging related to convective or stratiform rain could not be observed, as processed air masses were replaced by fresh dust transported in the upper Saharan air layer by the AEJ. Over southern Benin, the dust distribution appeared to be mostly controlled by processes affecting the planetary boundary layer upstream, i.e. over Nigeria or Chad. Because springtime dust from remote eastern sources (such as observed in this case) is mainly transported into the AEJ, it could impact on the radiation budget in the AEJ region, thereby possibly modifying the West African weather at the synoptic scale