Propylène glycol

Le propylène glycol (PG) ou propane-1,2-diol, appelé aussi 1,2-dihydroxypropane ou méthyl glycol, est un diol de formule chimique ayant de nombreux usages industriels ou agropharmaceutiques, à faible dose comme additif alimentaire (E1520) et depuis peu dans les cigarettes électroniques (liquide à vapoter). Le propylène-glycol est obtenu à partir de la réaction de l'oxyde de propylène avec l'eau pour former du monopropylène glycol (MPG), les réactions ultérieures produisant des di-(DPG), tri-(TPG) et autres propylène-glycols. Stéréochimie L'atome de carbone 2 est asymétrique. Le propane-1,2-diol est donc chiral et se présente sous la forme d'une paire d'énantiomères, l'énantiomère R étant lévogyre tandis que le S est dextrogyre. Le propylène glycol est le plus souvent sous la forme d'un racémique. Production La société PKN Orlen produit du propylène glycol à partir de glycérol issu de la production de biogazole dans son usine de Trzebinia en Pologne. Ut

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Deep thiopental anesthesia alters steady-state glucose homeostasis but not the neurochemical profile of rat cortex

Rolf Gruetter, Hongxia Lei

Barbiturates are regularly used as an anesthetic for animal experimentation and clinical procedures and are frequently provided with solubilizing compounds, such as ethanol and propylene glycol, which have been reported to affect brain function and, in the case of 1H NMR experiments, originate undesired resonances in spectra affecting the quantification. As an alternative, thiopental can be administrated without any solubilizing agents. The aim of the study was to investigate the effect of deep thiopental anesthesia on the neurochemical profile consisting of 19 metabolites and on glucose transport kinetics in vivo in rat cortex compared with α-chloralose using localized 1H NMR spectroscopy. Thiopental was devoid of effects on the neurochemical profile, except for the elevated glucose at a given plasma glucose level resulting from thiopental-induced depression of glucose consumption at isoelectrical condition. Over the entire range of plasma glucose levels, steady-state glucose concentrations were increased on average by 48% ± 8%, implying that an effect of deep thiopental anesthesia on the transport rate relative to cerebral glucose consumption ratio was increased by 47% ± 8% compared with light α-chloralose-anesthetized rats. We conclude that the thiopental-induced isoelectrical condition in rat cortex significantly affected glucose contents by depressing brain metabolism, which remained substantial at isoelectricity.

Wiley-Blackwell2010

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Investigation of Ethylene and Propylene Production from CO2 Reduction over Copper Nanocubes in an MEA-Type Electrolyzer

Raffaella Buonsanti, Valery Okatenko

Previous work carried out in fully liquid environ-ments and at low current densities has demonstrated that highly uniform faceted copper nanocrystals display different selectivity profiles in CO2 reduction compared to polycrystalline copper. As part of ongoing upscaling efforts, it is a matter of interest to investigate whether the high selectivity toward ethylene of copper nanocubes, which show a preferential (100) orientation, is maintained in gas-fed electrolyzers, thus enabling the energy-efficient production of this valuable commodity chemical at industrially relevant current densities. In this work, we assessed the electrochemical CO2 reduction reaction performance of highly uniform copper nanocubes loaded onto gas diffusion electrodes (GDEs) in a zero-gap device. The copper nanocube-loaded GDEs maintained high Faradaic efficiencies toward ethylene at elevated total current densities, resulting in higher overall partial current densities toward this product compared to benchmark electrodes. Interestingly, CO2 reduction to propylene, albeit with low partial current densities, was also observed. However, double-layer capacitance measurements revealed that the performance observed at high current densities is significantly influenced by electrode flooding. The findings of this study can inform future efforts geared toward optimizing the electrodes with this promising class of catalysts.

AMER CHEMICAL SOC2022

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Catalyst design for C-O bond hydrogenolysis of renewable materials.

Antoine Philippe Van Muyden

Anthropogenic carbon dioxide emissions leading to climate change require to use of renewable carbon sources such as CO2 and biomass which differ from fossil resources by having a higher number of oxygen atoms. Therefore, catalytic C-O bond cleavage will play a pivotal role in their conversion into carbon neutral fuels, materials and chemicals. This thesis will focus on the most challenging substrate for selective C-O bond hydrogenolysis, diaryl ether present in lignin (i.e. one of the components of biomass), summarise the state of research and improve the comprehension in the characteristics a catalyst requires to selectively cleave these bonds without altering other functionalities. We showed that the modification in the electronic state and the resulting polarity between two different metals present in a bimetallic nanoparticle favour the selectivity towards hydrogenolysis of a polar C-O bonds over aromatic ring hydrogenation. In addition, we demon-strate that single metal sites cannot hydrogenate an aromatic ring and hence are selective. Final-ly, we applied our knowledge in C-O bond cleavage in CO2 conversion using propylene carbonate as a relay molecule to produce propylene glycol and methane.

EPFL2020

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Glycérol

Le glycérol, ou glycérine, est un composé organique de formule . C'est un liquide incolore, visqueux et inodore au goût sucré, utilisé dans de nombreuses compositions pharmaceutiques. Sa molécule po

Éthylène glycol

L'éthylène glycol ou glycol ou encore éthane-1,2-diol est le plus simple composé chimique de la famille des glycols. Sa formule semi-développée est et sa formule brute . L'éthylène glycol est fréqu

Polyéthylène glycol

On appelle polyéthylène glycol ou PEG des polyéthers linéaires de masse molaire inférieure à fabriqués à partir de monomères d'éthylène glycol. Leurs propriétés hydrosolubles et liposolubles en fon

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ENV-507: Fate and behaviour of environmental contaminants

The student will learn the important processes that control the transport and transformation of organic chemicals in the environment, as well as the formulation and solution of quantitative models to describe these processes.

BIOENG-442: Biomaterials

This course covers the fundamental concepts behind the design, function and application of state-of-the-art biomaterials, that is, materials that are designed based on a molecular understanding of their interactions with biological systems.