Search results for "40"

Enhanced NiO Dispersion on a High Surface Area Pillared Heterostructure Covered by Niobium Leads to Optimal Behaviour in the Oxidative Dehydrogenatio…

2020

[EN] A Nb-containing siliceous porous clay heterostructure (PCH) with Nb contents from 0 to 30 wt %) was prepared from a bentonite and used as support in the preparation of supported NiO catalysts with NiO loading from 15 to 80 wt %. Supports and NiO-containing catalysts were characterised by several physicochemical techniques and tested in the oxidative dehydrogenation (ODH) of ethane. The characterisation studies on Nb-containing supports showed the presence of well-anchored Nb(5+)species without the formation of Nb(2)O(5)crystals. High dispersion of nickel oxide with low crystallinity was observed for the Nb-containing PCH supports. In addition, when NiO is supported on these Nb-containi…

Synthesis of 2-Aminothiazole Derivatives in Easy Two-Step, One-Pot Reaction

2018

Reactivity of [1,2,3]Triazolo[1,5-a]pyridines as 1,3-dipoles

2016

Abstract We have studied the reactions between [1,2,3]Triazolo[1,5- a ]pyridines 1a,b,c and electron-deficient ethylenes in different conditions. Compounds 1a and 1b react with ethyl propiolate, and dimethyl acetylene dicarboxylate giving a new class of biaryl compounds pyridyl pyrazoles, and with ethyl acrylate giving pyridyl cyclopropanes. Compound 1c did not give any product in the studied conditions. A proposal of mechanism of these reactions is done in which the triazolopyridines act as 1,3-dipoles giving 1,3-dipolar cycloadditions.

Unsymmetrically Substituted Bis(phosphino)Ferrocenes Triggering Through-Space 31(P, P′)-Nuclear Spin Couplings and Encapsulating Coinage Metal Cations

2021

International audience; We describe unsymmetrically substituted di-tert-butylated 1,1'-bis(phosphino)ferrocenes, with phosphino substituents R = [5-methyl]-2-furyl = Fu, and R' = phenyl (4a), i-propyl (4b). A modular synthetic approach was applied from the di-tert-butylated ferrocene platform (1), which lead to the formation of new diphosphines by using 1,1'bis(diiodo)-3,3'-bis(tert-butyl)ferrocene (2) as synthetic precursor. In contrast to the cousin non-alkylated unsymmetrically substituted diphosphino-ferrocenes which were reported up to now, these diphosphines showed strong (31 P, P')nonbonded (" ug-p e") nuclear spin-spin coupling. The strength of such internuclear spin-spin coupling c…

X-ray, conformation and electronic structures of 1-nitropyrrolidine

2016

Abstract The chemistry of pyrrolidine compounds has drawn much attention because of their biological activities. The crystal and molecular structure of 1-nitropyrrolidine (C4H8NNO2) at 150K, along with calculated structures (DFT and MP2), are reported herein. In the solid-state, the asymmetric part of the unit cell is composed of one quartermolecule at the position of two perpendicular mirror planes and the five-membered ring is disordered over a mirror plane, revealing the twisted conformation. Both geometries suggest slight sp3 hybridization of the amine nitrogen atom. The non-planar geometry suggests the lack of conjugation of the amine nitrogen lone pair with the nitro group, however th…

Facile synthesis of annulated heterocyclic benzo[kl]acridine derivatives via one-pot N–H/C–H coupling

2016

An efficient N–H/C–H one-pot coupling method for the preparation of benzo[kl]acridines has been developed based on palladium-catalyzed domino synthesis. Using commercially available starting materials such as dihalonaphthalenes and diphenylamines, and combining amination with catalysts for C–H activation, up to 95% overall yield can be achieved.

Diels–Alder reaction on perylenediimides: synthesis and theoretical study of core-expanded diimides

2019

A one-step reaction for the fusion of aromatic rings to one or both bay areas of perylenediimides using benzynes is presented. Yields as high as 70% for naphthoperylenendiimide 2 and 80% for dibenzocoronenediimide 3 are obtained. The reaction is also carried out using substituted benzynes, heteroaromatic benzynes and substituted perylenediimides. A combined experimental/theoretical approach, based on measuring redox and absorption/emission properties and performing density functional theory calculations, indicates that increasing the π-skeleton of PDIs transversally leads to significant and unexpected changes in the electronic, redox and optical properties. The observed trends are rationali…

Understanding the Participation of Fluorinated Azomethine Ylides in Carbenoid-Type [3 + 2] Cycloaddition Reactions with Ynal Systems: A Molecular Ele…

2021

The carbenoid-type (cb-type) 32CA reaction of 1,1-difluoroated azomethine ylide (DFAY) with phenylpropynal has been studied using the molecular electron density theory (MEDT). Electron localization function (ELF) characterizes DFAY as a carbenoid species participating in cb-type 32CA reactions. The supernucleophilic character of DFAY and the strong electrophilic character of the ynal cause this polar 32CA reaction to have an unappreciable barrier; the reaction, which is highly exothermic, presents total chemo- and regioselectivity. ELF topological analysis of the bonding changes along the reaction establishes its non-concerted two-stage one-step mechanism, in which the nucleophilic attack o…

Acceptorless dehydrogenative condensation: synthesis of indoles and quinolines from diols and anilines.

2021

The use of diols and anilines as reagents for the preparation of indoles represents a challenge in organic synthesis. By means of acceptorless dehydrogenative condensation, heterocycles, such as indoles, can be obtained. Herein we present an experimental and theoretical study for this purpose employing heterogeneous catalysts Pt/Al2O3 and ZnO in combination with an acid catalyst (p-TSA) and NMP as solvent. Under our optimized conditions, the diol excess has been reduced down to 2 equivalents. This represents a major advance, and allows the use of other diols. 2,3-Butanediol or 1,2-cyclohexanediol has been employed affording 2,3-dimethyl indoles and tetrahydrocarbazoles. In addition, 1,3-pro…

Planar Benzo[1,2-b:4,5-b′]dithiophene Derivatives Decorated with Nitronyl and Imino Nitroxides

2018

Four weakly antiferromagnetic interacting biradicals of benzo[1,2- b:4,5- b']dithiophene (BDT) and BDT extended with two thiophenes (BDTTh2) linked with nitronyl and imino nitroxides (NN and IN) as BDT-NN, BDT-IN, BDTTh2-NN, and BDTTh2-IN were designed, synthesized, and characterized. Short intermolecular π-π distances were found (3.42 A) for BDT-NN, whereas larger ones were found for BDT-IN (3.54 A) and BDTTh2-NN (3.67 A), respectively. Intramolecular magnetic interaction ( Jintra,exp/ kB) of BDT-NN (-26 K) is much larger than for BDT-IN (-5.3 K), while it is reduced for the dithiophene-extended molecule BDTTh2-NN (-2.3 K). Intermolecular interactions ( zJinter,exp/ kB) of BDT-NN (-6.5 K) …