Amine functionalization of N,N,N',N'-tetramethyl-p-phenylenediamine applicable to electrosynthesis a wide range of p-phenylenediamines in green conditions

2021 ◽  
Author(s):  
Fahimeh Varmaghani ◽  
Maryam Abbasi
Keyword(s):  
Aqueous Solutions ◽  
Striking Feature ◽  
Amine Functionalization ◽  
Wide Range ◽  
Green Conditions

The voltammogram features of TMPD2+/TMPD, N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD), reflect intensive instability of TMPD2+ in aqueous solutions. The instability of TMPD2+ strongly restricts applications of TMPD2+ in electrochemical syntheses. The striking feature...

Modeling of the Extraction of Lanthanide Nitrates from Aqueous Solutions Over a Wide Range of Activities by CMPO

2004 ◽  
Vol 22 (5) ◽  
pp. 791-811 ◽  
Author(s):  
S. Belair ◽  
C. Lamouroux ◽  
M. Tabarant ◽  
A. Labet ◽  
C. Mariet ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Wide Range ◽  
Lanthanide Nitrates

An enhanced enzymatic reaction using a triphase system based on superhydrophobic mesoporous nanowire arrays

2019 ◽  
Vol 4 (1) ◽  
pp. 231-235 ◽  
Author(s):  
Fengying Guan ◽  
Jun Zhang ◽  
Heming Tang ◽  
Liping Chen ◽  
Xinjian Feng
Keyword(s):  
Mass Transport ◽  
Aqueous Solutions ◽  
Reaction Kinetics ◽  
Enzymatic Reaction ◽  
Reaction System ◽  
Nanowire Arrays ◽  
System P ◽  
Wide Range

Gaseous reactants play a key role in a wide range of biocatalytic reactions, however reaction kinetics are generally limited by the slow mass transport of gases (typically oxygen) in or through aqueous solutions. Herein we address this limitation by developing a triphase reaction system.

The effect of background rotation on fluid motions: a report on Euromech 245

1990 ◽  
Vol 211 ◽  
pp. 417-435 ◽  
Author(s):  
E. J. Hopfinger ◽  
P. F. Linden
Keyword(s):  
Coherent Structures ◽  
Stratified Flows ◽  
Striking Feature ◽  
Nonlinear Phenomena ◽  
Linear Wave ◽  
Rotating Fluids ◽  
Nonlinear Processes ◽  
Recent Advances ◽  
Wide Range ◽  
Coherent Vortices

The 245th Euromech Colloquium, on the effect of background rotation on fluid motions, was held in Cambridge from 10–13 April 1989 with the two authors acting as chairmen. There were sixty-five participants with widely different backgrounds. The striking feature of the Colloquium was the recent advances on nonlinear processes. A wide range of nonlinear phenomena was presented and particular emphasis was on the formation and dynamics of coherent vortices. The similarities between the processes in rotating, curved and stratified flows, which lead to anisotropic motions and long-lived coherent structures alongside linear wave motions was a feature of many of the presentations. Fifty-one papers were presented, covering engineering, geophysical and astrophysical applications of rotating fluids. These papers are summarized in this report with the purpose of giving an up-to-date view of current research in rotating fluids.

Replacement of anhydrite by hydroxyapatite: kinetic and textural characteristics

2020 ◽  
Author(s):  
Ana Roza ◽  
Amalia Jiménez ◽  
Lurdes Fernández-Díaz
Keyword(s):  
Aqueous Solutions ◽  
Molar Volume ◽  
Sedimentary Basins ◽  
Rietveld Analysis ◽  
Calcium Sulphate ◽  
Wide Range ◽  
Polycrystalline Aggregates ◽  
Diagenetic Evolution ◽  
Inner Region ◽  
Highly Porous

<p>Interface-coupled dissolution-precipitation (ICDP) reactions lead to the pseudomorphic replacement of minerals in a wide range of geological settings, exerting a significant impact in geochemical cycles (Putnis 2002). ICDP reactions play a major role in the diagenetic evolution of sedimentary rocks, specially of limestones and evaporites. Recent experimental works have studied ICDP reactions that lead to the formation of CaCO<sub>3</sub> pseudomorphs after anhydrite (CaSO<sub>4</sub>), upon interaction of the latter phase with carbonated aqueous solutions. These pseudomorphs are highly porous polycrystalline aggregates that mainly consist of calcite (Roncal-Herrero et al. 2018; Altree-Williams et al. 2017). The formation of a large volume of interconnected microporosity that balances the molar volume loss associated to the anhydrite-calcite transformation as well as the specific arrangement of this microporosity, influenced by the existence of epitactic relationships between anhydrite and calcite, facilitate the progress of the ICDP reaction.</p><p>Here, we study the ICDP reaction that leads to the formation of hydroxyapatite (Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH)) pseudomorphs after the interaction of anhydrite with phosphate-bearing aqueous solutions at temperatures 90 to180ºC during times that range from one hour to five weeks. The X-ray diffraction Rietveld analysis of the transformed samples indicates that the kinetics of the pseudomorphic transformation of anhydrite into hydroxyapatite strongly depends on temperature.  Thus, while at 180ºC a 100% transformation yield is attained in few hours, it takes five weeks of interaction at 90ºC. Scanning Electron Microscopy imagining of transformed samples shows the very good preservation of both, the original external shape and microtopographic features of anhydrite crystals. On cross-cut sections of partially replaced by hydroxyapatite anhydrite crystals we observe that the transformation advances from the surface inwards, with sharp separating the by replaced layer from the unreacted anhydrite core. Furthermore, this replaced layer is structured into a compact ~ 50 µm thick outer rim, which consists of coalescent small (~ 5 µm) hydroxyapatite crystals, and a progressively thickening inner region formed by hydroxyapatite columnar crystals in a stockade-like arrangement. This latter region is highly porous. We interpret these results taking into consideration the differences in solubility and molar volume between anhydrite and hydroxyapatite as well as the similarities/differences between the crystal structures of these phases. By comparing the characteristics of different ICDP reactions that involve anhydrite in sedimentary basins we derive implications about the diagenetic evolution of calcium sulphate evaporites. </p><p> </p><p>Altree-Williams, Alexander, et al. (2017). <em>ACS Earth and Space Chemistry</em> 1.2, 89-100.</p><p>Roncal-Herrero, Teresa, et al. (2017): <em>American Mineralogist</em> 102.6, 1270-1278.</p><p>Putnis A: (2002): <em>Mineralogical Magazine</em> 66.5, 689-708.</p><p> </p><p> </p>

scholarly journals Staminal wing and a novel secretory structure of asclepiads

Botany ◽  
2017 ◽  
Vol 95 (7) ◽  
pp. 763-772 ◽  
Author(s):  
Diego Demarco
Keyword(s):  
Flower Development ◽  
Striking Feature ◽  
Guide Rail ◽  
Secretory Structures ◽  
Floral Ontogeny ◽  
Floral Buds ◽  
Wide Range

Asclepiads (Asclepiadoideae, Apocynaceae) have morphologically complex flowers with a wide range of secretory structures related to their defense and pollination. A striking feature of the flowers is the presence of a guide rail formed by staminal wings, which is related to the guidance of the pollinator to the pollinarium translator and the retention of the pollinium. Previous analyses of floral ontogeny in asclepiads detected the presence of a possible gland on the staminal wing during flower development. The goal of the present study was to verify the occurrence of a secretory structure on the staminal wing and its possible function through ontogenetic and histochemical analyses of the presumed gland. Staminal wings are formed early in developing flowers, and a gland is originated in the outer and inner margins of the guide rail in all species. This gland releases a secretion composed of mucilage and lipids, which likely assists in the introduction of the pollinator appendage into the narrow guide rail by lubricating the staminal wings. The gland degenerates before anthesis, increasing the space within the guide rail and enabling the introduction of the pollinarium. This new secretory structure may be present in floral buds of all asclepiads.

scholarly journals A study of 12-tungstosilicic and 12-molybdophosphoric acids in solution

2008 ◽  
Vol 73 (2) ◽  
pp. 197-209 ◽  
Author(s):  
Danica Bajuk-Bogdanovic ◽  
Ivanka Holclajtner-Antunovic ◽  
Marija Todorovic ◽  
Ubavka Mioc ◽  
Joanna Zakrzewska
Keyword(s):  
Nmr Spectroscopy ◽  
Aqueous Solutions ◽  
Special Importance ◽  
Molybdophosphoric Acid ◽  
Physiological Conditions ◽  
Tungstosilicic Acid ◽  
Ir And Nmr Spectroscopy ◽  
Wide Range ◽  
Catalytic Applications ◽  
Anion Type

The behaviour of two heteropolyacids (HPAs) with quite different stability in aqueous solutions was systematically investigated by UV, IR and NMR spectroscopy and potentiometric titration. It was shown that the Keggin structure of 12-tungstosilicic acid (H4SiW12O40, WSiA) anion was sustained over a wide range of pH from 1.0 to 7.0, while the same anion type of 12-molybdophosphoric acid (H3PMo12O40, MoPA) was present only at pH 1.0. This means that under physiological conditions WSiA is dominantly present in the form of a Kegginanion, whereas the structure of MoPA is completely decomposed to molybdate and phosphate. The obtained results are of special importance for bio-medical and catalytic applications of these compounds and for a better understanding of the mechanism of their action.

Electron paramagnetic resonance study of the reactions of the spin trap 3,5-dibromo-4-nitrosobenzenesulfonate

1988 ◽  
Vol 66 (5) ◽  
pp. 1153-1158 ◽  
Author(s):  
Peter Smith ◽  
Jill Suzanne Robertson
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Aqueous Solutions ◽  
Electron Paramagnetic Resonance Study ◽  
Oxidation Mechanism ◽  
Azo Compounds ◽  
Electronic Effects ◽  
Paramagnetic Resonance ◽  
Wide Range ◽  
Methacrylic Monomers ◽  
Electron Paramagnetic

Using rapid-mixing, continuous-flow TiCl3-based techniques and also by means of static-sample studies involving the thermal decomposition of symmetric aliphatic azo compounds, we have characterized by electron paramagnetic resonance 22 spin adducts of 3,5-dibromo-4-nitrosobenzenesulphonate, 1, in aqueous solution at 25 °C. These spin adducts, all nitroxides, exhibit a moderately wide range of a-nitrogen and β-CH proton splitting constants, which we discuss in terms of steric and electronic effects. In connection with these studies, blank experiments showed that aqueous solutions of 1 gave no radicals when exposed to light and heat. In addition, we have studied by electron paramagnetic resonance at 25 °C static samples of aqueous solutions of 1 both by itself and in the presence of each of several acrylic and methacrylic monomers and in both the presence and absence of light. These solutions yielded radicals, namely, nitroxides, only when containing methacrylic monomers, the presence of light having no effect. These observations support the "ene" addition/oxidation mechanism of nitroxide formation.

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