Search results for "Reaction condition"
showing 10 items of 70 documents
Dissolution and hydrolysis of fibre sludge using hydroxyalkylimidazolium hydrogensulphate ionic liquids
2014
Abstract The dissolution and hydrolysis of wet fibre sludge in ionic liquids (ILs) with different reaction conditions are performed in this study. Novel types of hydroxyalkylimidazolium hydrogensulphate ILs, [glymim]HSO 4 , [hemim]HSO 4 and [hpmim]HSO 4 , are especially designed and aimed to combine the dissolution and hydrolysis of wet fibre sludge in a one-step pretreatment. The results were obtained based on the analysis of total reducing sugars (TRS) with the DNS method. The dissolution and hydrolysis of fresh wild horse chestnut fruit ( Aesculus hippocastanum ) with the same ILs were also carried out as a comparison reference. Since fibre sludge is cellulose based and horse chestnut fr…
A Combination of Visible-Light Organophotoredox Catalysis and Asymmetric Organocatalysis for the Enantioselective Mannich Reaction of Dihydroquinoxal…
2019
[EN] An enantioselective photooxidative Mannich reaction of dihydroquinoxalinones with ketones by the merger of organophotoredox and asymmetric organocatalysis is described. This protocol features very mild reaction conditions using simple and cheap catalysts (Eosin Y and (S)-Proline) for the synthesis of chiral quinoxaline derivatives with good to high yields (up to 94%) and excellent enantioselectivities (up to 99% ee).
Regio-specific synthesis of new 1-(tert-butyl)-1H-pyrazolecarboxamide derivatives
2017
Regio-specific and non-regiospecific condensation reactions on 1,3-dicarbonyl compounds rendered 1,3,5-trisubstituted pyrazoles. Herein, the control of regio-specificity was a significant improvement in pyrazole research. A high yield acylation of poorly nucleophilic aryl amines, which resulted in mono- or diacylated products depending on the reaction conditions, is described. As a result, a library of potentially bioactive compounds was obtained. Fil: Ruatta Merke, Santiago Matías. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina Fil: Murguia, Marcelo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Co…
Untersuchungen zur Diastereoselektivität beim O ‐Angriff von Elektrophilen auf β‐Ketocarbonsäureester‐Enolate
1989
Aus den in reiner Form eingesetzten Z- oder E-Enolen 2a–c werden uber die Enolatstufe 3a–c die O-alkylierten, -silylierten oder -acylierten Produkte 4aa–ae, 4ba, bf und 4ca, cc, cf hergestellt. Im Gegensatz zu der vollstandigen Regioselektivitat hangt die Z/E-Diastereoselektivitat dabei von den Substituenten in 2/3, dem verwendeten Elektrophil und den Reaktionsbedingungen ab. Insbesondere bei weichen Elektrophilen kann sich das Z/E-Verhaltnis bei der Umsetzung 34 stark andern. On the Diastereoselectivity of the O-Attack of Electrophiles on Enolates from β-Ketocarboxylates The O-alkylated, -silylated or -acylated derivatives 4aa–ae, 4ba, bf, 4ca, cc, cf of the pure Z or E enoles 2a–c are gen…
Photochemie des 1,3,5‐Tristyrylbenzols
1984
In Abhangigkeit von den Reaktionsbedingungen erhalt man bei der Belichtung der Titelverbindung 1 das Cyclophan 5, das Pyrenderivat 6 oder das polykondensierte aromatische System 9. Fur den neuen Cyclophantyp 5, bei dem zwei Benzolringe selbst wieder durch Ringe verbruckt sind, wurde eine Rontgenstrukturanalyse durchgefuhrt. Photochemistry of 1,3,5-Tristyrylbenzene Depending on the reaction conditions the irradiation of the title compound 1 yields the cyclophane 5, the pyrene derivative 6, or the polycondensed aromatic system 9. An X-ray analysis was performed for 5, representing a new type of cyclophane in which two benzene rings are bridged again by rings.
Synthesen mit substituierten Malondialdehyden, XI. γ‐Formyl‐tetramethinmerocyanin‐, γ‐Formyl‐pentamethincyanin‐ und [2.2.2]Heptamethincyanin‐Farbstof…
1972
Durch Kondensation des Formylmalondialdehyds (Triformylmethan) 5 mit heterocyclischen Imoniumsalzen 4 werden je nach Reaktionsbedingungen neuartige γ-Formyl-tetramethinmerocyanin-(6), γ-Formyl-pentamethincyanin-(8) und trinucleare symmetrische [2.2.2]Heptamethincyanin-Farbstoffe (9) dargestellt. Die Isolierung der Mono- (6) und Dikondensationsprodukte (8) des Formylmalondialdehyds ermoglicht die Darstellung unsymmetrischer Farbstoffe 8 und 9 mit verschiedenen Endgruppen. — Die trinuclearen [2.2.2]Heptamethincyanine 9 lassen sich in Analogie zu den phenylogen Guanidiniumionen (Triphenylmethanfarbstoffe) als methinyloge Guanidiniumkationen 3 (n = 3) auffassen. — Die spektroskopischen Eigensch…
Direct formation of Sub-Micron and Nanoparticles of a bioinspired coordination polymer based on Copper with Adenine
2017
We report on the use of different reaction conditions, e.g., temperature, time, and/or concentration of reactants, to gain control over the particle formation of a bioinspired coordination polymer based on copper(II) and adenine, allowing homogeneous particle production from microto submicro-, and up to nano-size. Additionally, studies on this reaction carried out in the presence of different surfactants gives rise to the control of the particle size due to the modulation of the electrostatic interactions. Stability of the water suspensions obtained within the time and pH has been evaluated. We have also studied that there is no significant effect of the size reduction in the magnetic prope…
The rate of polymerization in two loci reaction systems: VDF-HFP precipitation copolymerization in supercritical carbon dioxide
2011
When the copolymerization of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) is carried out in supercritical carbon dioxide (scCO 2) under heterogeneous conditions, the reaction occurs both in the continuous CO 2-rich phase and in the dispersed polymer-rich phase. The two phases being characterized by different values of reactant concentrations and kinetic parameters, one would expect that the reaction kinetics is affected by the polymer phase holdup in the reactor. However, the reaction rate is almost insensitive to the amount of produced polymer, at least at specific reaction conditions. This apparent contradiction is discussed and clarified in this paper by a series of comparativ…
Biomimetic chitosan-mediated synthesis in heterogeneous phase of bulk and mesoporous silica nanoparticles
2009
Both bulk and mesoporous silica nanoparticles can be obtained in the form of granular aggregates using chitosan flakes as additive under very soft biomimetic reaction conditions. Puchol Estors, Victoria, Victoria.Puchol@uv.es ; El Haskouri, Jamal, Jamal.Haskouri@uv.es ; Latorre Saborit, Julio, Julio.Latorre@uv.es ; Beltran Porter, Aurelio, Aurelio.Beltran@uv.es ; Beltran Porter, Daniel, Daniel.Beltran@uv.es ; Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es
Alkylation of Benzene with Short-Chain Olefins over MCM-22 Zeolite: Catalytic Behaviour and Kinetic Mechanism
2000
Abstract Benzene alkylation with ethene and propene has been carried out under liquid-phase reaction conditions over zeolites MCM-22, Beta, and ZSM-5. MCM-22 seems to be a good catalyst for benzene alkylation especially with propene, showing high activity and stability and good selectivity. Kinetic experiments show that alkylation with propene follows an Eley–Rideal type mechanism.