Search results for "ALK"

Cu(ii)-alginate-based superporous hydrogel catalyst for click chemistry azide-alkyne cycloaddition type reactions in water.

2020

A novel sustainable hydrogel catalyst based on the reaction of sodium alginate naturally extracted from brown algae Laminaria digitata residue with copper(II) was prepared as spherical beads, namely Cu(II)-alginate hydrogel (Cu(II)-AHG). The morphology and structural characteristics of these beads were elucidated by different techniques such as SEM, EDX, BET, FTIR and TGA analysis. Cu(II)-AHG and its dried form, namely Cu(II)-alginate (Cu(II)-AD), are relatively uniform with an average pore ranging from 200 nm to more than 20 μm. These superporous structure beads were employed for the copper catalyzed [3 + 2] cycloaddition reaction of aryl azides and terminal aryl alkynes (CuAAC) via click …

Maleic diamide polymerizable surfactants. Applications in emulsion polymerization

2003

Abstract A series of new polymerizable non-ionic and ionic surfactants (surfmers) with amides groups on both sides of the C=C double bonds have been prepared upon reaction of maleic isoimide carrying a long alkyl chain (or a benzyl group) with a hydrophilic amine derivative. Their critical micellar concentration (CMC) was measured with a surface tensiometer. They have been engaged in batch emulsion polymerization of styrene, and semi-batch seeded copolymerization of styrene and butyl acrylate, giving stable latexes during the polymerization process, and upon extraction with ethanol, showing a high rate of incorporation at the particle surface. However these surfmers do not confer good steri…

Synthesis and biological evaluation of the new ring system benzo[f]pyrimido[1,2-d][1,2,3]triazolo[1,5-a][1,4]diazepine and its cycloalkane and cycloa…

2021

Derivatives of the new ring system benzo[f]pyrimido[1,2-d][1,2,3]triazolo[1,5-a][1,4]diazepinone and its cycloalkane and cycloalkene condensed analogues have been conveniently synthesized through a three-step reaction sequence. An atom-economical, one-pot, three-step cascade process engaging five reactive centers (amide, amine, carbonyl, azide, and alkyne) has been performed for the synthesis of alicyclic derivatives of quinazolinotriazolobenzodiazepine using cyclohexane, cyclohexene, and norbornene β-amino amides. The stereochemistry and relative configurations of the synthesized compounds were determined by 1D and 2D NMR spectroscopy and X-ray crystallography. The reaction was also perfor…

Photo-fragmentation of alkyl phosphates in the gas-phase

2018

Abstract Alkyl phosphates are experiencing an ever increasing use due to the current arising of new applications. This implies their increasing presence in the environment so their stability and reactivity under high-energy photons, which are still unknown, need to be clarified. In this study, a mass spectrometric investigation of the ionization and fragmentation processes of four representative alkyl phosphates (dibutyl, tributyl, bis-2-ethylhexyl, and tris-2-ethylhexyl phosphate) induced by vacuum ultraviolet (VUV) radiation has been carried out. The experimental data show that fragmentation occurs through a stepwise cleavage of the bonds between the phosphate group and the alkyl chains l…

Highly fluorescent and photostable organic- and water-soluble CdSe/ZnS core-shell quantum dots capped with thiols

2012

Highly fluorescent organic- and water-soluble CdSe/ZnS core-shell quantum dots (QDs) with thiol ligands chemisorbed on the QD surface were synthesized by the replacement of amine ligands by alkyl thiols under very mild conditions. The QDs exhibited an even greater photostability than the initial core-shell amine capped QDs.

Complexation of enantiomerically pure tetraalkylammonium cations by ethyl resorcinarene

2013

Molecular recognition via weak interactions of three enantiopure tetraalkylammonium cations 2–4 by ethyl resorcinarene 1 was studied in the solid state using single-crystal X-ray diffraction, in solution by proton nuclear magnetic resonance spectroscopy (1H NMR) titration and in the gas phase using electrospray ionisation mass spectrometry. The 1H NMR titration studies reveal the association constants for the 1:1 complexes to vary according to the size and electronic properties of the alkyl groups of the guest cations. In the solid state, the resorcinarene is deprotonated and the X-ray structure confirms the 1:1 complex 2+@1−  to be held together by multiple cation…π and C–H…π interactions.…

High Yield Syntheses of Stable, Singly Bonded Pd26+ Compounds

2006

A general method for the syntheses of dipalladium compounds having a singly bonded Pd26+ core and the formula R,S-cis-Pd2(C6H4PPh2)2(O2CR)2Cl2 is described. When the alkyl group in the carboxylate ligands is an electron donating group, the compounds are stable and the yields high. The Pd-Pd distances for the diamagnetic compounds with R = CF3 and CMe3 are 2.5434(4) and 2.5241(9) A, respectively. Calculations at the DFT level suggest that the electronic configuration is sigma2pi4delta2delta*2pi*4. These represent rare examples of palladium(III) compounds.

Iron-Catalyzed C(sp2)-C(sp3) Cross-Coupling of Alkyl Grignard Reagents with Polyaromatic Tosylates

2017

Cover Feature: Metal‐ and Reagent‐Free Electrochemical Synthesis of Alkyl Arylsulfonates in a Multi‐Component Reaction (Chem. Eur. J. 38/2020)

2020

N-Alkyl Ammonium Resorcinarene Salts: A Versatile Family of Calixarene-Related Host Molecules

2016

This chapter presents a review of the recent advances in the chemistry of N-alkylammonium resorcinarenes salt receptors. The Mannich condensation between amines (primary and secondary) and resorcinarenes result in resorcinarene tetrabenzoxazines and tetra-azoxazines. Only 2 isomers out of 16 potential isomers are formed. The resorcinarene tetrabenzoxazines possess deeper cavities than the parent resorcinarenes which are suitable for binding neutral and cationic guests. In the presence of mineral acids, the six-membered oxazine ring in the resorcinarene tetrabenzoxazines is opened, resulting in N-alkylammonium resorcinarene salts (NARSs). The NARSs possess four spatially-fixed anions within …