Search results for "Esteri"
showing 10 items of 220 documents
Microwave-assisted catalytic esterification of α-glucoisosaccharino-1,4-lactone with tall oil fatty acids
2016
Background: Carbohydrates-rich materials are partly degraded during alkaline kraft pulping into a complex mixture of aliphatic carboxylic acids consisting of α-glucoisosaccharinic acid as one of the main acids. On the other hand, crude tall oil, containing significant amounts fatty acids, is obtained as a by-product from kraft pulping. One interesting novel approach is to utilize chemically both these side-streams by producing renewable surfactants from aliphatic carboxylic acids and fatty acids via esterification. Results: In this paper, lauric (C12:0) and oleic (C18:1) acids as well as a mixture of tall oil fatty acids were esterified with α-glucoisosaccharino-1,4-lactone in a microwave-a…
Cluster Preface: Heterogeneous Catalysis
2016
International audience; Jean-Cyrille Hierso is full professor of Chemistry since 2009, heading the group of ‘Organometallic Chemistry and Catalysis’ at the Institute of Molecular Chemistry at the University of Bourgogne Franche-Comté (UBFC). He has interest in the fields of organometallic chemistry, ligand design, homo- and heterogeneous catalysis, chemical physics, and material sciences. In 2011 he was awarded the National Prize for Coordination Chemistry from the French Chemical Society (SCF), and at the end of 2012 he was elected a junior Member of the French Professors Academy ‘Institut Universitaire de France’ (IUF).Yasuhiro Uozumi is a full professor at the Institute for Molecular Sci…
Undecylenic acid: A tunable bio-based synthon for materials applications
2016
International audience; An undecylenic acid-based monoglyceride prepared from glycidol and undecylenic acid is used as suitable and tunable synthon for polymerization applications. Epoxidation and acrylation reactions lead to photopolymerizable monomers while transesterification with dimethyl carbonate, metathesis and aminolysis reactions provide access to polyhydroxyurethane-based materials. The successive intermediates were synthesized according to a green chemistry approach implicating solvent-less and catalyzed reactions, and were at each step fully characterized by infrared, 1H and 13C{1H} NMR spectroscopy, elemental analysis and mass spectrometry. Analyses of the resulting polymer mat…
Holskābes un tās atvasinājumu solvātu veidošanās un desolvatācijas mehānisms
2015
Holskābes un tās atvasinājumu solvātu veidošanās un desolvatācijas mehānisms. Zvaniņa D., darba vadītāji prof. Actiņš A., Mg.Chem. Bērziņs A. Maģistra darbs, 60 lappuses, 27 attēli, 6 tabulas, 47 literatūras avoti, 3 pielikumi. Latviešu valodā. Darbā tika pagatavots holskābes metilestera dimetilformamīda solvāts un, kristalizējot holskābes metilesteri no izo-propanola, n-propanola un izo-butilspirta, iegūta holskābes metilestera I polimorfā forma. Kristalizējot holskābi, henodeoksiholskābi un ursodeoksiholskābi no dažādiem organiskajiem šķīdinātājiem, tika iegūti holskābes etanola, metanola un acetonitrila solvāti un henodeoksiholskābes nitrometāna solvāts. Iegūtās cietās fāzes tika pārbaud…
Pacienta dzīvesveida izmaiņas hiperholesterinēmijas gadījumā
2015
Bakalaura darba tēma – “Pacienta dzīvesveida izmaiņas hiperholesterinēmijas gadījumā”. Paaugstināts holesterīna līmenis jeb hiperholesterinēmija ir viens no galvenajiem cēloņiem saslimšanā ar sirds asinsvadu slimībām un insultu. Globāli kopumā trešā daļa no sirds išēmiskām slimībām ir saistīta ar paaugstinātu holesterīna līmeni. Pasaulē ar hiperholesterinēmiju saskaras vairāk kā 5,6 miljoni cilvēku. Bakalaura darba literatūras apskata daļā tiek aprakstīts, kas ir holesterīns, hiperholesterinēmija, tās cēloņi un ietekme uz organismu un veselīga dzīvesveida nozīme pie hiperholesterinēmijas. Bakalaura darba tēmai tika izvēlēta un analizēta V. Hendersones māszinības teorija, par cilvēka nepieci…
Characterization of Acylating and Deacylating Activities of an Extracellular Phospholipase A2 in a Water-Restricted Environment
1994
The behavior of porcine pancreatic phospholipase A2 (ppPLA2) in monophasic low-water media has been explored, for the first time, in a systematic manner. It has been investigated how a number of variables can modulate both acylating and deacylating activities of the enzyme, and several interesting, unexpected results are presented. Among the most relevant, when placing ppPLA2 in the water-restricted environment, are the following: (i) it displays a remarkable alteration of its specificity toward the substrate polar head relative to all-water medium; (ii) it is quite severely inhibited by lysophosphatidylcholine (LPC), which has important implications, particularly concerning its acylation a…
Development of Kesterite (Cu2ZnSnS4) absorber material for solar cell application.
2021
Kesterite-based solar cells still suffer from limited efficiency due to various problems related to the absorber and device interfaces. Absorber defects and non-ideal band alignment at the absorber/buffer hetero-interface, resulting in a cliff-like conduction band offset (CBO), and non-ideal absorber/back contact interfaces are the main factors limiting efficiency.This thesis focuses mainly on the absorber-related problems such as the secondary phases and the band alignment at the absorber-buffer heterojunction as well as the back interface.In the first part, the properties of the absorber layer were studied. Thin layers of Cu2ZnSnS4 (CZTS) were obtained by chemical route. This study reveal…
Innesto di catene polimeriche sulla superficie di nanotube di carbonio mediante reazione di accoppiamento radicalico
2015
La modifica di nanotubi di carbonio (CNT) attraverso innesto (grafting) di catene polimeriche sulla loro superficie è un metodo efficace per promuovere la dispersione di queste cariche a livello nanometrico in una matrice polimerica. La funzionalizzazione covalente di CNT con catene polimeriche viene generalmente ottenuta sia attraverso crescita controllata di polimeri a partire dalle pareti della nanocarica mediante metodi "grafting from" sia attraverso metodi di "grafting to" che si basano sulla reazione di condensazione tra polimeri preformati e CNT opportunamente modificati. In questo lavoro viene proposto un nuovo approccio di tipo "grafting to" per innestare catene polimeriche su CNT …
Sequestering ability of some chelating agents towards methylmercury(II).
2013
A study on the interactions between CH3Hg+ and some S, N and O donor ligands (2-mercaptopropanoic acid (thiolactic acid (H2 TLA)), 3-mercaptopropanoic acid (H2 MPA), 2-mercaptosuccinic acid (thiomalic acid (H3 TMA)), d,l-penicillamine (H2 PSH), l-cysteine (H2 CYS), glutathione (H3 GSH), N,N′-bis(3-aminopropyl)-1-4-diaminobutane (spermine (SPER)), 1,2,3,4,5,6-benzenehexacarboxylic acid (mellitic acid (H6 MLT)) and ethylenediaminetetraacetic acid (H4 EDTA)) is reported. The speciation models in aqueous solution and the possible structures of the complexes formed are discussed on the basis of potentiometric, calorimetric, UV spectrophotometric and electrospray mass spectrometric results. For t…
Interesterification of rapeseed oil catalysed by a low surface area tin (II) oxide heterogeneous catalyst
2018
Abstract The interesterification of rapeseed oil was performed in a batch reactor using for the first time low surface area massive tin(II) oxide as heterogeneous catalyst and methyl acetate as acyl acceptor. The effect of reaction temperature, methyl acetate to oil molar ratio and catalyst loading on the performances of the process were investigated. Yields in fatty acid methyl esters (FAMEs) and triacetin (TA) up to 90% and 70% respectively, were achieved after 4 h of reaction time at 483 K in the presence of 0.69 mol of SnO per mole of rapeseed oil using a methyl acetate to oil molar ratio of 40. Quite interestingly, the catalyst performances improved when water was added to the reaction…