نتایج جستجو برای: enantiomeric excess

تعداد نتایج: 75059  

1999
Jianhua Guo Jiangyue Wu Gary Siuzdak M. G. Finn

The powerful nature of combinatorial synthetic methods for the preparation of diverse libraries of small molecules has often made the analysis of such compounds the rate-limiting step in their application.[1] An intriguing target is the discovery of new enantioselective catalytic processes by the testing of large numbers of candidate catalysts.[2] Optimal use of combinatorial synthesis in this ...

2006
J. Williams

Monoterpenes, emitted in large quantities by trees to attract pollinators and repel herbivores, can exist in mirror image forms called enantiomers. In this study such enantiomeric pairs have been measured in ambient air over extensive forest ecosystems in South America and northern Europe. For the dominant monoterpene, α-pinene, the (−)form was measured in large excess over the (+)-form over th...

Journal: :Analytical chemistry 2006
Chieu D Tran Daniel Oliveira Shaofang Yu

We have successfully synthesized both enantiomers of a novel chiral ionic liquid, (R)- and (S)-[(3-chloro-2-hydroxypropyl) trimethylammonium][bis((trifluoromethyl)sulfonyl)amide] ((R)- and (S)-[CHTA]+[Tf2N]-) in optically pure form by a simple ion exchange reaction from corresponding chloride salts that are commercially available. In addition to the ease of preparation, this chiral IL has relat...

2013
Franco Cataldo Susana Iglesias-Groth Giancarlo Angelini Yaser Hafez

A series of non-proteinogenic amino acids, most of them found quite commonly in the meteorites known as carbonaceous chondrites, were subjected to solid state radiolysis in vacuum to a total radiation dose of 3.2 MGy corresponding to 23% of the total dose expected to be taken by organic molecules buried in asteroids and meteorites since the beginning of the solar system 4.6 × 109 years ago. The...

2014
José C. Aponte Jason P. Dworkin Jamie E. Elsila

The study of meteoritic organic compounds provides a unique window into the chemical inventory of the early Solar System and prebiotic chemistry that may have been important for the origin of life on Earth. Multiple families of organic compounds have been extracted from the Murchison meteorite, which is one of the most thoroughly studied carbonaceous chondrites. The amino acids extracted from M...

2015
Mohammad M Rafiee Fanood N. Bhargava Ram C. Stefan Lehmann Ivan Powis Maurice H. M. Janssen

Simultaneous, enantiomer-specific identification of chiral molecules in multi-component mixtures is extremely challenging. Many established techniques for single-component analysis fail to provide selectivity in multi-component mixtures and lack sensitivity for dilute samples. Here we show how enantiomers may be differentiated by mass-selected photoelectron circular dichroism using an electron-...

2006
Yukio Saito Takeshi Sugimori Hiroyuki Hyuga

Stochastic aspects of chemical reaction models related to the Soai reactions as well as to the homochirality in life are studied analytically and numerically by the use of the master equation and random walk model. For systems with a recycling process, a unique final probability distribution is obtained by means of detailed balance conditions. With a nonlinear autocatalysis the distribution has...

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