Search results for "Aqueous medium"

Synthesis of bi- and tricyclic β-lactam libraries in aqueous medium

2007

Water as a solvent is not only inexpensive and environmentally benign, but may allow good reactivity. The present work focuses on the application of a modified Ugi reaction, i.e. the Ugi four-centre three-component reaction (U-4C-3CR), in aqueous medium to construct β-lactam libraries. All the attempted reactions could be successfully performed in water. The reaction conditions under which the precipitation process was effective were investigated; no further work-up or purification was necessary. In several cases when less water-soluble β-amino acids were used, the precipitated products were isolated easily by simple filtration. In other cases, evaporation of the solvent was appropriate for…

Supramolecular Polymers in Aqueous Media

2016

This review discusses one-dimensional supramolecular polymers that form in aqueous media. First, naturally occurring supramolecular polymers are described, in particular, amyloid fibrils, actin filaments, and microtubules. Their structural, thermodynamic, kinetic, and nanomechanical properties are highlighted, as well as their importance for the advancement of biologically inspired supramolecular polymer materials. Second, five classes of synthetic supramolecular polymers are described: systems based on (1) hydrogen-bond motifs, (2) large π-conjugated surfaces, (3) host-guest interactions, (4) peptides, and (5) DNA. We focus on recent studies that address key challenges in the field, provid…

Function of biomolecules as a probe for studying the effects of organic co-solvents on their conformations

1980

Abstract Conformation changes associated with the function of biomolecules can bring out variations of the extent and specific structure of their hydrophobic areas exposed to solvent, with consequent local rearrangements of the solvent. This is one of the channels through which the solvent exerts its role in the functional equilibria of biomolecules. The function of biological macromolecules in perturbed aqueous solvent can therefore be a suitable probe for studying the response of macromolecule-solvent systems to perturbations caused by organic co-solvents. We shall discussed the effects that the presence of some monohydric alcohols and some amides in the aqueous medium have on some thermo…

Cyclodextrins in Polymer Synthesis:  Free Radical Copolymerization of Methylated β-Cyclodextrin Complexes of Hydrophobic Monomers with N-Isopropylacr…

2000

Methylated β-cyclodextrin (me-β-CD) was used to form water-soluble host/guest complexes with the hydrophobic monomers n-butyl methacrylate (1), cyclohexyl methacrylate (2), isobornyl acrylate (3), isobornyl methacrylate (4), and styrene (5), respectively. The free-radical copolymerizations of the water-soluble N-isopropylacrylamide (NIPAAm) with these complexed monomers were carried out in water at different molar ratios.

Cyclodextrins in Polymer Synthesis:  Free Radical Polymerization of a N-Methacryloyl-11-aminoundecanoic Acid/β-Cyclodextrin Pseudorotaxane in an Aque…

1999

The relatively hydrophobic monomer N-methacryloyl-11-aminoundecanoic acid (1) was incorporated as a guest into the cavity of β-cyclodextrin (β-CD) as a host, yielding the water-soluble monomer N-me...

Novel Porphyrin-Cholic Acid Conjugates as Receptors for Biologically Important Anions

2005

A series of novel receptors showing high binding affinity in aqueous media for biologically important anions are reported. These naturally chromophoric porphyrin-based receptors contain cholic acids connected via quaternary alkyl ammonium amido linkages.

Die copolymerisation des acroleins mit einigen vinylmonomeren. Polymere acroleine. 9. Mitt.

1958

Die Copolymerisation des Acroleins in wasrigem Medium wird untersucht und die copolymerisationsparameter folgender Systeme bestimmt: Acrolein/Aacrylnitril (r1 = 1,09; r2 = 0,77); Acrolein/Acrylamid (r1 = 2,0; r2 = 0,76); Acrolein/Acrylsauremethylester (r1 = 0,2; r2 = 10,0) und Acrolein/Vinylacetat (r1 = 3,3; r2 = 0,1). Ferner werden die Qund e-Werte fur Acrolein berechet und sein Verhalten bei der Copolymerisation diskutiert. The copolymerisation of acrolein in aqueous medium has been investigated and the reactivity ratios of the following systems were determined: acrolein/acrylonitrile (r1 = 1.09; r2 = 0.77 ); acrolein/acrylamide (r1 = 2.0; r2 = 0.76); acrolein/methacrylate (r1 = 0.2; r2 =…

ChemInform Abstract: Highlights on Contemporary Recognition and Sensing of Fluoride Anion in Solution and in the Solid State

2013

The fluoride anion has recently gained well deserved attention among the scientific community for its importance in many fields of human activities, but also for concerns on its effect on health and the environment. Although surprisingly overlooked in systematic studies in the past, fluoride has nowadays become a topical target in the field of anion recognition. A multitude of scientific reports are published every year where the establishment of efficient and specific interaction with fluoride is sought in polar and aqueous media. Here, the emphasis is directed to a detailed description of the most interesting contemporary studies in the field, with a particular focus given to those publis…

A Highly Enantioselective Access to Tetrahydroisoquinoline and β-Carboline Alkaloids with Simple Noyori-Type Catalysts in Aqueous Media

2009

ChemInform Abstract: Water-Soluble Palladium Nanoparticles: Click Synthesis and Applications as a Recyclable Catalyst in Suzuki Cross-Couplings in Aq…

2011

Polyethylene glycol-tagged macrocycle (I) is prepared by a three-fold copper-catalyzed [3 + 2] cycloaddition reaction.