Enantioselective hydrolysis of amino acid esters in organized hybrid assemblies.

Ueoka, Ryuichi; Matsumoto, Yōko; Matsuo, Naruto; Taguchi, Takahiro; Ubata, S.

doi:10.1246/nikkashi.1989.181

Cited by 3 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A summary of earlier work can be found in the reviews by Bunton and Savelli and from Kunitake and Shinkai. [67,196] Mechanistic considerations have been reported, for example, by Moss et al [197] as well as by Ueoka et al [198] Moss et al [197] made the observation that alcohols formed from the nitrosation of optically active secondary amines in a micellar medium showed up to 22 % retention, while inversion was predominately found for the same reaction in water-clearly water attacks the intermediate carbenium ion from various sides. The effect of the micellar medium is promoted by hydrophobic counterions such as BF 4 À or ClO 4 À , as these can occupy the back side of the carbenium ion.…”

Section: Enantioselective Reactionsmentioning

confidence: 93%

Reactions in Micellar Systems

2005

View full text Add to dashboard Cite

The notion of "green chemistry" has encouraged even synthetic organic chemists to include water as a solvent. Incredible selectivities and activities can be achieved through the addition of amphiphiles with a defined structure. The morphology of supramolecular assemblies or associates formed by surfactants vary according to the temperature and concentration. As a rule, reactions are typically conducted using simple spherical aggregates, that is, micelles in the nanometer range. The strong polarity gradient present between the hydrophilic surface and the hydrophobic core of the micelle means that both nonpolar and polar reagents can be solubilized. This solubilization results in reactants becoming more concentrated within the micelle than in the surrounding water phase and leads to an acceleration of the reaction and causes selective effects. The kinetic treatment of reactions in micellar systems can be accomplished by considering them as microheterogeneous two-phase systems.

show abstract

Section: Enantioselective Reactionsmentioning

confidence: 93%

Reactions in Micellar Systems

2005

View full text Add to dashboard Cite

show abstract

Reaktionen in micellaren Systemen

2005

View full text Add to dashboard Cite

Die Vorstellung einer “grünen Chemie” hat selbst den präparativ arbeitenden Organiker ermutigt, Wasser als Lösungsmittel in Betracht zu ziehen. Durch Zusätze von Amphiphilen bestimmter Struktur kann man erstaunliche Aktivitäten und Selektivitäten erzielen. Die von den Tensiden gebildeten Assoziate variieren in ihrer Morphologie je nach Temperatur und Konzentration. In der Regel arbeitet man im Bereich einfacher sphärischer Aggregate, der nanometergroßen Micellen. Da in Micellen ein starker Polaritätsgradient von der hydrophilen Oberfläche zum hydrophoben Kern vorliegt, können sowohl unpolare als auch polare Reaktanten solubilisiert werden. Dadurch kommt es oft im Vergleich zur umgebenden Wasserphase zu einer Konzentrierung der Reaktionspartner und damit zu einer Beschleunigung der Reaktion. Darüber hinaus treten selektive Effekte auf. Micellare Systeme können kinetisch als mikroheterogene Zweiphasensysteme behandelt werden.

show abstract