4,459 research outputs found
Ferrocene in agriculture: from agrochemicals and soil remediation to selective chemosensors
No full textFerrocene and derivatives find numerous application in agriculture, both as agrochemicals and as catalysts for selective synthesis of agrochemicals. Moreover, they can be used as surfactants in soil remediation and as selective colorimetric and electrochemical chemosensors for analytes of interest in agriculture
Vanadium catalyzed oxidation with hydrogen peroxide
No full textVanadium peroxides are known as very effective oxidants af different organic and inorganic substrates. In this short account reactivity, structural and mechanistic studies concerning the behaviour of peroxovanadates toward a number of different substrates are collected. Homogeneous and two-phases systems are presented, in addition, interesting synthetic results obtained with the use of ionic liquids as reaction media are also presented
Poster P15: Excited states of molecular solutes with Quantum Monte Carlo: vertical transition and geometry optimization
No full textRecently, we have developed a novel Polarizable Continuum Model (PCM), which includes both surface and volume polarization of the dielectric medium (pure SVPE scheme), designed for the Quantum Monte Carlo (QMC) treatment of the solute. In particular, the treatment of volume polarization, due to quantum mechanical penetration of the solute charge density in the solvent domain, is based on quantum Monte Carlo techniques. The method allows to accurately solve Poisson's equation of the solvation model coupled with the Schrödinger equation for the solute [1,2,3]. The present model has been now extended to treat the effects of solvation in solute vertical electronic transitions and to the search of the solute equilibrium geometry in the excited states. For the first case, here we show the results of our study
performed on fast n → pi* and pi → pi* vertical transitions of s-trans- acrolein in water [4]. To perform calculations in a non-equilibrium solvation regime for the solute excited state, we have added a correction to the global dielectric polarization charge density, obtained self consistently with the solute ground-state wave function by assuming a linear-response scheme. The calculated solvatochromic shifts are properly described. For the second case, we start from recent
advances made to carry out the ground- and excited-state geometry optimization within QMC [5]. For the present purpose, we have extended the calculation of the forces to include solvent e_ects through our QMC implementation of PCM [6]. We show results, performed at the variational Monte Carlo level, on the excited-state geometry optimization of some small organic molecules in water solution and we make a comparison with the more widely used TDDFT and CASPT2 methods.
[1] C. Amovilli, C. Filippi, F. M. Floris, J. Phys. Chem. B (2006) 110 26225.
[2] C. Amovilli, C. Filippi, F. M. Floris, J. Chem. Phys. (2008) 129 244106.
[3] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2012) 137 075102.
[4] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2014) 140 034109.
[5] R. Guareschi, C. Filippi, J. Chem. Theor. Comput. (2013) 9 5513.
[6] R. Guareschi, F. M. Floris, C. Amovilli, C. Filippi, in preparation (2014)
On the B-Semiampleness Conjecture
No full textThe B-Semiampleness Conjecture of Prokhorov and Shokurov predicts that themoduli part in a canonical bundle formula is semiample on a birationalmodification. We prove that the restriction of the moduli part to anysufficiently high divisorial valuation is semiample, assuming the conjecture inlower dimensions.Comment: 26 page
The addition of 2,4-dinitrobenzenesulfenyl chloride to some alkyl-substituted vinylferrocenes
No full textThe addition of 2,4-dinitrobenzenesulfenyl chloride to alkyl-substituted vinylferrocenes has been investigated in CH2Cl2, 1,1,2,2-tetrachloroethane and acetic acid solutions. Product analyses were carried out by VPC and PMR techniques and reaction rates measured by a spectrophotometric method. The orientation appears to be determined by the structural features of the intermediate episulfonium ion rather than by the site of the primary attack of the electrophile on the starting substrate. A comparison with the results previously obtained with the methoxymercuration reaction has a bearing on the mechanism of the latter reactio
Reaction of ethynylferrocene with arenesulphenyl chlorides
No full textThe reaction of ethynylferrocene with arenesulphenyl chlorides [ArSCl; Ar = Ph, p-ClC6H4, p-MeC6H4, p-MeOC 6H4, p-NO2C6H4, or 2,4-(NO2)2C6H3] follows an unusual pathway; the main outcome is substitution of the acetylenic proton, rather than electrophilic addition to the triple bond. The following compounds were isolated and identified: FcC≡CSAr, FcCCl=CHSAr, and FcCCl=CH2 or FcCOCH3 (Fc = ferrocenyl), depending on the reaction conditions. A mechanistic scheme is proposed
Chimica consapevole, responsabile, sostenibile: la sfida entra nella scuola
No full textConscious, Responsible, Sustainable Chemistry. The Challenge Goes to School
Green chemistry is more and more diffuse in academics, its principles are gaining favor and followers among scientists, aware of the huge problems related
to environment depletion and not renewable energetic sources. It is time that green chemistry principles enter the school and thereby the society. After a brief
presentation and explanation of green chemistry principles, a number of successful practical applications is reported
The kinetics and mechanism of the protodeboronation of ferroceneboronic acid in moderately concentrated sulfuric acid
No full textFerroceneboronic acid has been characterized by its UV and NMR spectrum and its dissociation constant in water/ethanol solvents has been determined. The kinetics of protodeboronation have been studied in the same solvents containing moderate concentrations of sulfuric acid; the H0 acidity function has been evaluated throughout the range of the reaction media used. The log of the rate of reaction of ferroceneboronic acid depends linearly with unit slope on H0. The solvent hydrogen isotope effect, the temperature dependence and the nature of acid catalysis have also been investigated. The reaction probably proceeds by an A-SE2-type mechanism
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