Some comments on the possibility of achieving asymmetric synthesis from achiral reactants in a rotating vessel

Mead, C. Alden; Moscowitz, Albert

doi:10.1021/ja00544a024

Cited by 36 publications

(10 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the evaluation of the ratio of rate constants corresponds to an ee as low as 3 × 10 -5 % which should be achievable with magnetic flux densities of up to 10 4 G (1.0 T) and an electric field strength of 10 3 V/cm. Although De Gennes found merit in the idea of these kinetic effects, they were considered unconvincing by other authors based not only on time reversal invariance but also on the condition of detailed balancing . We have however indicated the validity of the argument by Rhodes and Dougherty by showing that a falsely chiral influence might induce an enantiomeric excess under kinetic conditions. 1g,,, …”

Section: A Magnetic and Electric Fieldsmentioning

confidence: 71%

Absolute Asymmetric Synthesis under Physical Fields: Facts and Fictions

et al. 1998

View full text Add to dashboard Cite

Section: A Magnetic and Electric Fieldsmentioning

confidence: 71%

Absolute Asymmetric Synthesis under Physical Fields: Facts and Fictions

et al. 1998

View full text Add to dashboard Cite

“…In previous work, the determination of a small deviations from the true racemic composition has been performed by inadequate means, leading to an unreliable conclusion. Thus the claim of asymmetric synthesis in a rapidly spinning reaction vessel utilizing chiral gravitational fields, 28 disputed on theoretical grounds, 29,30 was solely based on few milli degrees of optical rotation whereby inherent polarimetric fluctuations were ignored. Polarimetry may only be considered for the screening of near-racemic mixtures when the compound in question exhibits an exceedingly large optical rotatory power.…”

Section: à13mentioning

confidence: 99%

Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of α‐amino acids with emphasis on tyrosine: Accuracy and precision of the method

et al. 2007

View full text Add to dashboard Cite

Whereas the determination of high enantiomeric fractions (EF) of chiral compounds is very well established, the accurate determination of small deviations from racemic compositions has not yet received much attention despite its relevance to studies dealing with the origin of homochirality, where only small initial enantiomeric bias is expected. Racemic samples of representative alpha-amino acids were derivatized as N-(O,S)-trifluoroacetyl/ethylesters and analyzed by enantioselective gas chromatography (GC) on fused silica capillaries coated with the chiral stationary phases (CSPs) Chirasil-D-Val, Chirasil-L-Val, and Lipodex E with GC/FID and GC/MS detection. The validation (accuracy and precision) of the determination of the enantiomeric fraction EF of the D-enantiomer in racemic or near-racemic compositions for 10 DL-alpha-amino acids obtained from commercial sources has been carried out. Emphasis is given to DL-tyrosine, the enantiomers of which have recently been claimed to show different crystallization properties. Values of EF obtained from GC measurements using CSPs were compared with those from CE using chiral mobile phase additives. While the precision of the GC method is generally better than 0.08% for all DL-alpha-amino acids studied, accuracy (trueness) of determination of amino acids with polar side chains is poorer than expected from the precision as a result of systematic errors. The accuracy determined relied on measurements on two oppositely configurated CSPs.

show abstract

“…Although several experimental studies report chirality-specific flow effects-on scales from molecular (porphyrin aggregation during rotary evaporation) 14,15 , through microscopic (helical bacteria 4 and particles 16 ), to macroscopic 13,17,18 -they remain largely phenomenological. Part of the problem is the possibly ambiguous interpretation of data [19][20][21] (for example, from circular dichroism) and the experimental design in which vortex flows are implemented with imprecise systems such as rotary evaporators or magnetic stirrers 22 , for which the flow structure on different length scales is largely unknown.…”

mentioning

confidence: 99%

Vortex flows impart chirality-specific lift forces

et al. 2015

View full text Add to dashboard Cite

Recent reports that macroscopic vortex flows can discriminate between chiral molecules or their assemblies sparked considerable scientific interest both for their implications to separations technologies and for their relevance to the origins of biological homochirality. However, these earlier results are inconclusive due to questions arising from instrumental artifacts and/or insufficient experimental control. After a decade of controversy, the question remains unresolved-how do vortex flows interact with different stereoisomers? Here, we implement a model experimental system to show that chiral objects in a Taylor-Couette cell experience a chirality-specific lift force. This force is directed parallel to the shear plane in contrast to previous studies in which helices, bacteria and chiral cubes experience chiralityspecific forces perpendicular to the shear plane. We present a quantitative hydrodynamic model that explains how chirality-specific motions arise in non-linear shear flows through the interplay between the shear-induced rotation of the particle and its orbital translation. The scaling laws derived here suggest that rotating flows can be used to achieve chiral separation at the micro-and nanoscales.

show abstract

Some comments on the possibility of achieving asymmetric synthesis from achiral reactants in a rotating vessel

Cited by 36 publications

References 0 publications

Absolute Asymmetric Synthesis under Physical Fields: Facts and Fictions

Absolute Asymmetric Synthesis under Physical Fields: Facts and Fictions

Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of α‐amino acids with emphasis on tyrosine: Accuracy and precision of the method

Vortex flows impart chirality-specific lift forces

Contact Info

Product

Resources

About