1,720,976 research outputs found
Synthesis of DPA-triazole structures and their application as ligand for metal catalyzed organic reactions
No full textIn this work, the use of DPA-triazole (DPA = dipicolylamine) molecules as ligands for metal catalyzed organic reactions has been investigated. A small library of ligands has been prepared by a CuAAC (click reaction) between propargyl-DPA and different azides. For a selected ligand the complexation with Zn(II) in solution has been investigated by NMR and MS. DFT calculation supported the structure of the complex as revealed by NMR data. The ligand was then used for metal-catalyzed organic transformation. The Henry reaction between nitromethane and aromatic aldehydes was efficiently catalyzed by the Zn(II)-DPA-triazole complex with only 2 mol% of catalyst. Changing the metal from Zn(II) to Cu(II), the system proved to be effective in the formation of acetals from the reaction of aldehydes and methanol or ethanol, thus revealing the versatility of the DPA-triazole ligand. Finally, a soluble polymer-supported ligand was used in the Zn(II) catalyzed Henry reaction, allowing for the recovery and reuse of the catalyst up to five times without evident loss of activity
From deep eutectic solvents to deep band gap systems
No full textThe optical properties of nine choline-based Deep Eutectic Solvents (DESs) of the type choline+X− (X− = chloride or acetate)/Y (Y = ethylene glycol, glycolic or levulinic acid) were studied by measuring their band gap through the UV-VIS-based Tauc method. All the considered systems showed a direct optical transition. A correlation between band gap and eutectic composition was discovered by plotting the variation of the band gap versus the molar fraction of choline+X−/Y in the parent systems containing 10 wt% of H2O. The main parameters influencing the energy of the optical transition in these “Deep Band Gap Systems” (DeBaGS) where studied through Design of Experiments (DoE) combined with multivariate analysis. The effect on the band gap of the anion (chloride or acetate), the acid (levulinic or glycolic), the water, and the stirring time, considered as single factor or in combination was clarified. Thus a multivariate model was implemented through surface responding analysis which allows engineering such kind of systems and opening to further applications in material science
Synthesis and Characterization of New Triazole-Bispidinone Scaffolds and Their Metal Complexes for Catalytic Applications
Full text linkBispidines are a family of ligands that plays a pivotal role in various areas of coordination chemistry, with applications in medicinal chemistry, molecular catalysis, coordination polymers synthesis, and molecular magnetism. In the present work, triazole moieties were introduced using the CuAAC click-reaction, with the aim of expanding the number of coordination sites on the bispidine core. The 1,2,3-triazole rings were thus synthesized on propargyl-derived bispidines after reaction with different alkyl azides. The new class of triazole-bispidines was characterized, and their chelation capabilities were evaluated with different metals through NMR titration, ESI-MS spectrometry, and single-crystal X-ray diffraction (SC-XRD). Finally, the suitability of these molecules as metal ligands for the catalytic Henry reaction was demonstrated with copper and zinc
In Competition for Water: Hydrated Choline Chloride:Urea vs Choline Acetate:Urea Deep Eutectic Solvents
Full text linkUnlike the archetypal deep eutectic solvent (DES) choline chloride:urea (ChCl:U), fundamental knowledge of the intermolecular network in choline acetate (ChOAc) DESs and how they change upon dilution is still missing. Here we jointly use UV resonance Raman (UVRR) and NMR spectroscopy to comparatively explore how the strength and distribution of hydrogen bonding and the solvation of the components are modified in ChOAc:U and ChCl:U with increasing hydration. Overall, Raman and NMR data indicate that ChOAc:U is continuously affected by hydration and, even at low water concentrations, undergoes a breakage of DES-DES interactions, with rapid solvation of the urea portion and full exchange of mobile protons. On the contrary, ChCl:U seems to maintain its structure as small interplays gradually occur between urea in the DES and the surrounding water molecules. The combined approach provides a multifaceted consistent description of the systems, outlining the crucial role of the anion in driving the structure and dynamics of the materials and then yielding valuable data toward the exploitation of DESs as tunable systems
A limescale composition
No full textUso come decalcificante o anticalcare di una composizione comprendente:
a) un primo solvente scelto tra:
a1) un solvente eutettico costituito da un accettore di legame idrogeno e da un donatore di legame idrogeno,
a2) un liquido ionico o
a3) una miscela di detto solvente eutettico e detto liquido ionico;
eventualmente in associazione con un secondo solvente b) scelto tra almeno un alcol inferiore, acqua o relative miscele,
in cui
nel primo solvente eutettico a1) l’accettore di legame idrogeno e il donatore di legame idrogeno sono privi di alogeni
Process for extracting and purifying chitin by using green solvents
No full textProcess for the treatment of biomass comprising chitin with a process solvent selected from a eutectic solvent consisting of a hydrogen bond acceptor and a hydrogen bond donor, an ionic liquid and/or a mixture of said eutectic solvent and said ionic liquid, said process comprising the following steps: A. mixing the biomass with the process solvent; B. separating the chitin precipitated in step A. from the remainder of the mixture; wherein: i. the hydrogen bond acceptor is a choline salt with a C2-C6 organic acid, and containing at least one carboxyl group and optionally substituted in the alkyl chain with at least one hydroxyl group, ii. the hydrogen bond donor is an organic acid selected from: glycolic acid, diglycolic acid, levulinic acid, or is imidazole; provided that when choline glycolate is used as a hydrogen bond acceptor, the hydrogen bond donor must be different from glycolic acid; iii. in step A. a polar protic solvent soluble in both said process solvent and water is added to the process solvent; selected from a linear or branched C1-C6 aliphatic alcohol; iv. the ionic liquid is the salt resulting from the exchange reaction between one of the organic acids used as a hydrogen bond donor listed above in point ii. and a choline salt specified in i. used as a hydrogen bond acceptor
Processo per il trattamento di biomasse
No full textProcesso per il trattamento di biomasse lignocellulosiche con un solvente di processo scelto tra un solvente eutettico, un liquido ionico o una miscela di detto solvente eutettico e detto liquido ionico
Deep eutectic solvent as solvent and catalyst: One-pot synthesis of 1,3-dinitropropanes via tandem Henry reaction/Michael addition
No full textThe Henry reaction was performed using microwave heating within the deep eutectic solvent (DES)
choline chloride/urea (ChCl/urea) which acted as both the catalyst and solvent for the reaction. The
optimisation of the conditions (temperature, heating mode, time, DES) allowed 1,3-dinitropropane derivatives
to be obtained via tandem Henry reaction/Michael addition, in one step from a range of different
aromatic aldehydes in high yields and under mild reaction condition
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