Photochemical synthesis of a “cage” compound in a microreactor: Rigorous comparison with a batch photoreactor

An intramolecular [2 + 2] photocycloaddition is performed in a microphotoreactor (0.81 mL) built by winding FEP tubing around a commercially available Pyrex immersion well in which a medium pressure mercury lamp is inserted. A rigorous comparison with a batch photoreactor (225 mL) is proposed by means of a simple model coupling the reaction kinetics with the mass, momentum and radiative transfer equations. This serves as a basis to explain why the chemical conversion and the irradiation time are respectively increased and reduced in the microphotoreactor relative to those in the batch photoreactor. Through this simple model reaction, some criteria for transposing photochemical synthesis from a batch photoreactor to a continuous microphotoreactor are defined

La micro-échelle en synthèse organique : un outil commun chimie/génie chimique

Cet article est une restitution courte de la présentation réalisée au cours des JIREC 2013 sur l’enseignement de la notion de changement d’échelle et de passage d’un mode batch à un mode continu en synthèse organique. L’enjeu est de faire travailler des étudiants issus des départements chimie et génie chimique autour d’un même outil, le microréacteur. Au cours d’une séance de travaux pratiques, les étudiants mettent en oeuvre une synthèse organique en continu à micro-échelle et comparent les résultats obtenus à ceux du procédé batch. Ils appréhendent ainsi la notion de synthèse en continu et de suivi cinétique le long du microréacteur et comprennent l’intérêt et les difficultés liés à la petite échelle. L’outil microréacteur mis en place à l’INP-ENSIACET peut être transféré vers d’autres formations de type ingénieurs, mais aussi CPGE, BTS ou IUT, pour accompagner le lien entre les domaines « génie de la réaction » et « synthèse organique »

Gold(I) complexes bearing phosphole ligands: Synthesis and antimalarial activity

AbstractA series of gold(I)-monophosphole complexes have been synthesized and characterized. The introduction of a nitrogen moiety in the complex structure was envisioned either by choosing the bis(trifluoromethanesulfonyl)imidate ligand as the X-ligand or by preparing a new pyrrolidinophosphole ligand as the L-ligand. All the complexes have been evaluated in vitro for their antimalarial activity. These gold–phosphole complexes showed moderate activities with IC50 values ranging from 9.7 to 24 μM against Plasmodium falciparum chloroquine-resistant strains

Performance of serum biomarkers for the early detection of invasive aspergillosis in febrile, neutropenic patients: a multi-state model

International audienceBACKGROUND: The performance of serum biomarkers for the early detection of invasive aspergillosis expectedly depends on the timing of test results relative to the empirical administration of antifungal therapy during neutropenia, although a dynamic evaluation framework is lacking.METHODS: We developed a multi-state model describing simultaneously the likelihood of empirical antifungal therapy and the risk of invasive aspergillosis during neutropenia. We evaluated whether the first positive test result with a biomarker is an independent predictor of invasive aspergillosis when both diagnostic information used to treat and risk factors of developing invasive aspergillosis are taken into account over time. We applied the multi-state model to a homogeneous cohort of 185 high-risk patients with acute myeloid leukemia. Patients were prospectively screened for galactomannan antigenemia twice a week for immediate treatment decision; 2,214 serum samples were collected on the same days and blindly assessed for (1->3)- β-D-glucan antigenemia and a quantitative PCR assay targeting a mitochondrial locus.RESULTS: The usual evaluation framework of biomarker performance was unable to distinguish clinical benefits of β-glucan or PCR assays. The multi-state model evidenced that the risk of invasive aspergillosis is a complex time function of neutropenia duration and risk management. The quantitative PCR assay accelerated the early detection of invasive aspergillosis (P = .010), independently of other diagnostic information used to treat, while β-glucan assay did not (P = .53). CONCLUSIONS: The performance of serum biomarkers for the early detection of invasive aspergillosis is better apprehended by the evaluation of time-varying predictors in a multi-state model. Our results provide strong rationale for prospective studies testing a preemptive antifungal therapy, guided by clinical, radiological, and bi-weekly blood screening with galactomannan antigenemia and a standardized quantitative PCR assay

Retour d'expérience sur un dispositif de Réflexivité et de Contextualisation en formation d'ingénieur par Apprentissage : RéCAp

International audienceRéCAp est un dispositif de problématisation permettant de mettre en lien les expériences professionnelles vécues en entreprise et les savoirs académiques dispensés dans les formations par apprentissage de Toulouse INP-ENSIACET. L’objectif de ce dispositif est double : (i) pour les élèves, il s’agit de les initier à une analyse réflexive de leurs activités et de leur positionnement en entreprise et de les accompagner dans la co-construction de leurs apprentissages à partir de la mise en relation des expériences en entreprise et des enseignements à l’école, (ii) pour les enseignants, il s’agit de leur donner l’opportunité de mieux contextualiser leurs enseignements et de mieux appréhender la notion de compétences au travers de situations authentique complexes. Par ailleurs, ce dispositif est suffisamment souple pour être adapté à différents contextes et il permet de relever le défi de la coopération via sa dimension collaborative tant au niveau des élèves que des enseignants

Microreactors as a Tool for Acquiring Kinetic Data on Photochemical Reactions

For the first time, the application of microreactors as a tool for acquiring kinetic data on a photochemical reaction is demonstrated. For illustration, a T-photochromic system is considered. By using modeling tools and carrying out specific experiments in a spiral-shaped microreactor irradiated by an ultraviolet/light-emitting diode (UV-LED) array, the two kinetic parameters of the reaction, namely, quantum yield and rate of thermal back reaction, are determined. Once these parameters are known, the photochromic reaction is performed in two other microreactors in order to investigate a wider range of operating conditions. It is observed that a critical residence time exists beyond which the conversion into the open form decreases due to a decomposition reaction. The value of the critical residence depends on the microreactor type, which can be predicted by applying the model developed

Photooxygenation in an advanced led-driven flow reactor module: experimental investigations and modelling

The photooxygenation of  α-terpinene was investigated as a benchmark reaction in an advanced LED-driven flow reactor module, both from an experimental and modelling point of view. Ethanol was used as a green solvent and rose Bengal was chosen as a cheap sensitizer of industrial importance. Firstly, the kinetic law based on all mechanistic steps was established for the chosen photooxygenation. From this, the set of operating parameters potentially influencing the photoreaction rate were identified. Subsequently, experiments were carried out under continuous-flow conditions to screen these operating parameters, namely concentration of α-terpinene, concentration of photosensitizer, residence time, structure of the segmented gas-liquid flow and nature of the reagent gas phase (air versus pure oxygen). Finally, the conditions enabling minimization of sensitizer bleaching were established. It was also shown that the hydrodynamic characteristics of the gas-liquid flow can have an effect on the conversion levels. From this, a simplified model was proposed to predict the conversion at the reactor’s outlet when pure oxygen was used

Transposition of a triphosgene-based process for pharmaceutical development: from mg·h-1 to kg·h-1 of an unsymmetrical urea

A two reaction synthesis of a urea, using triphosgene, was studied. The objective was to transpose the process from laboratory scale to pre-industrial plant. The whole study was performed in a continuous process, adapting the characteristic dimensions and length of the reactor. In this paper, the development of the process is presented, and the choices about safety and operating conditions constraints are discussed. The final operation allows a 70% global yield in a 7 week study. Furthermore, the use of microreactors not only permits an exhaustive study of the process operating parameters, but also provides feedback on the developed chemistry itself. The results obtained are a demonstration of the use of continuous processes in small scale reactors for complex molecule development. The mg·h-1 to kg·h-1 is a key transposition in the pharmaceutical industries project development, as it can help to accelerate the first lot production used in toxicological or pre-clinic stages

A revised experimental protocol for implementing the actinometry method with the Reinecke’s salt

The present short note aims at proposing a revised experimental protocol to implement the actinometry method with Reinecke’s salt. It consists in substituting - for the dosing of the thiocyanate anions produced - perchloric acid (HClO4) by nitric acid (HNO3) - the latter being carefully chosen regarding the chemical equilibria occurring in the aqueous medium and the moderate risks of HNO3. This substitution has been rigorously validated by carrying out the experiments in a dedicated torus batch photoreactor enabling simple treatment of experimental results from a one-dimensional model