220 research outputs found
A kinetic study of the basic hydrolysis of 2-phenylethyl nitrite in the presence of borate buffer and β-cyclodextrin
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WO3 and Ionic Liquids: A Synergic Pair for Pollutant Gas Sensing and Desulfurization
This review deals with the notable results obtained by the synergy between ionic liquids
(ILs) and WO3 in the field of pollutant gas sensing and sulfur removal pretreatment of fuels. Starting
from the known characteristics of tungsten trioxide as catalytic material, many authors have proposed
the use of ionic liquids in order to both direct WO3 production towards controllable nanostructures
(nanorods, nanospheres, etc.) and to modify the metal oxide structure (incorporating ILs) in order
to increase the gas adsorption ability and, thus, the catalytic eciency. Moreover, ionic liquids are
able to highly disperse WO3 in composites, thus enhancing the contact surface and the catalytic
ability of WO3 in both hydrodesulfurization (HDS) and oxidative desulfurization (ODS) of liquid
fuels. In particular, the use of ILs in composite synthesis can direct the hydrogenation process (HDS)
towards sulfur compounds rather than towards olefins, thus preserving the octane number of the fuel
while highly reducing the sulfur content and, thus, the possibility of air pollution with sulfur oxides.
A similar performance enhancement was obtained in ODS, where the high dispersion of WO3 (due to
the use of ILs during the synthesis) allows for noteworthy results at very low temperatures (50 C)
Natural Compounds as Sustainable Additives for Biopolymers
In the last few decades, the interest towards natural compounds, coming from a natural
source and biodegradable, for biopolymers is always increasing because of a public request for the
formulation of safe, eco-friendly, and sustainable materials. The main classes of natural compounds
for biopolymers are: (i) naturally occurring fillers (nFil), such as nano-/micro- sized layered
alumino-silicate: halloysite, bentonite, montmorillonite, hydroxyapatite, calcium carbonate, etc.; (ii)
naturally occurring fibers (nFib), such as wood and vegetable fibers; (iii) naturally occurring
antioxidant molecules (nAO), such as phenols, polyphenols, vitamins, and carotenoids. However,
in this short review, the advantages and drawbacks, considering naturally occurring compounds as
safe, eco-friendly, and sustainable additives for biopolymers, have been focused and discussed
briefly, even taking into account the requests and needs of different application fields
The Gelling Ability of Some Diimidazolium Salts: Effect of Isomeric Substitution of the Cation and Anion
The gelling ability of some geminal imidazolium salts was investigated
both in organic solvents and in water solution. Organic
salts differing either in the cation or anion structure
were taken into account. In particular, the effects on the gelphase
formation of isomeric substitution on the cation or
anion as well as of the use of mono- or dianions were evaluated.
As far as the cation structure is concerned, isomeric cations,
such as 3,3’-di-n-octyl-1,1’-(1,4-phenylenedimethylene)diimidazolium
and 3,3’-di-n-octyl-1,1’-(1,3-phenylenedimethylene)
diimidazolium, were used. On the other hand, in addition
to the bromide anion, isomeric dianions, such as the 1,5- and
2,6-naphthalenedisulfonate anions, were also examined. After
preliminary gelation tests, different factors affecting the obtained
gel phases, such as the nature of the solvent, organogelator
concentrations, and action of external stimuli, were analyzed.
The gel-phase formation was also studied as a function
of time, by using resonance light scattering measurements. Gel
morphologies were analyzed by scanning electron microscopy.
To further support the understanding of the different behavior
shown by the isomeric cations, some representative ion pairs
were analyzed by DFT-based investigations. The collected data
underline the significant role played by isomeric substitution
of both cation and anion structures in determining the gelling
capability of the investigated salts, as well as the properties of
the gel phases. Finally, DFT investigations were helpful in the
identification of the structural features affecting the self-assembly
A competitive reactivity study on the oxidative cyclization of thiosemicarbazones into 1,3,4-thiadiazolidines
Abstract
In order to obtain useful insights on the mechanism of formation of 2(3H)-imino-1,3,4-thiadiazoles by
oxidative cyclization of aldehyde thiosemicarbazones with Cu(II) or Fe(III) salts, a competitive reactivity study
was performed on a suitable set of diversely substituted substrates, by means of HPLC techniques. This
approach enabled to exploit Hammett\u2019s equation without performing otherwise difficult-to-run kinetic
experiments. The results presented herein support the hypothesis that the formation of the thiadiazole ring is
induced by the attack of the oxidizing Lewis acid metal cation onto the imine-like nitrogen atom of the
thiosemicarbazone substrate. Beyond mechanistic interpretation, the paper particularly focuses onto the
methodological issues implied
Variable Temperature Synthesis of Tunable Flame-Generated Carbon Nanoparticles
In this study, flame-formed carbon nanoparticles of different nanostructures have been produced by changing the flame temperature. Raman spectroscopy has been used for the characterization of the carbon nanoparticles, while the particle size has been obtained by online measurements made by electrical mobility analysis. The results show that, in agreement with recent literature data, a large variety of carbon nanoparticles, with a different degree of graphitization, can be produced by changing the flame temperature. This methodology allows for the synthesis of very small carbon nanoparticles with a size of about 3–4 nm and with different graphitic orders. Under the perspective of the material synthesis process, the variable-temperature flame-synthesis of carbon nanoparticles appears as an attractive procedure for a cost-effective and easily scalable production of highly tunable carbon nanoparticles
Cyclodextrin-[60]fullerene conjugates: synthesis, characterization, and electrochemical behavior
Thermodynamics of binding between alfa- and beta-cyclodextrins and some p-nitro-aniline derivatives: reconsidering the enthalpy-entropy compensation effect
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