Enantiomeric Excess
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Chiral Separation of Rac-Propylene Oxide on Penicillamine Coated Gold Nps
nanomaterials Article Chiral Separation of rac-Propylene Oxide on Penicillamine Coated Gold NPs Nisha Shukla 1,2, Zachary Blonder 2 and Andrew J. Gellman 2,3,* 1 Institute of Complex Engineered Systems, Carnegie Mellon University, Pittsburgh, PA 15213, USA; [email protected] 2 Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA; [email protected] 3 W.E. Scott Institute for Energy Innovation, Carnegie Mellon University, Pittsburgh, PA 15213, USA * Correspondence: [email protected] Received: 16 July 2020; Accepted: 20 August 2020; Published: 30 August 2020 Abstract: The surfaces of chemically synthesized spherical gold NPs (Au-NPs) have been modified using chiral L- or D-penicillamine (Pen) in order to impart enantioselective adsorption properties. These chiral Au-NPs have been used to demonstrate enantioselective adsorption of racemic propylene oxide (PO) from aqueous solution. In the past we have studied enantioselective adsorption of racemic PO on L- or D-cysteine (Cys)-coated Au-NPs. This prior work suggested that adsorption of PO on Cys-coated Au-NPs equilibrates within an hour. In this work, we have studied the effect of time on the enantioselective adsorption of racemic PO from solution onto chiral Pen/Au-NPs. Enantioselective adsorption of PO on chiral Pen/Au-NPs is time-dependent but reaches a steady state after ~18 h at room temperature. More importantly, L- or D-Pen/Au-NPs are shown to adsorb R- or S-PO enantiospecifically and to separate the two PO enantiomers from racemic mixtures of RS-PO. Keywords: chiral; nanoparticles; enantioselective adsorption; penicillamine; cysteine 1. Introduction Chirality has attracted enormous interest in the field of chemistry due to the enantiospecific responses of living organisms to the two enantiomers of chiral compounds that they have ingested. -
Chiral Auxiliaries and Optical Resolving Agents
Chiral Auxiliaries and Optical Resolving Agents Most bioactive substances are optically active. For instance, if This brochure introduces a variety of chiral auxiliaries and a substance is synthesized as a racemic compound, its optical resolving agents. We hope that it will be useful for your enantiomer may show no activity or even undesired bioactivity. research of the synthesis of optically active compounds. Thus, methods to gain enantiopure compounds have been Additionally, TCI has some brochures introducing chiral developed. When synthesizing enantiopure compounds, the compounds for the chiral pool method in “Chiral Building Blocks”, methods are roughly divided into three methods. “Terpenes”, “Amino Acids” and other brochures. Sugar derivatives are also introduced in a catalog, “Reagents for Glyco Chemistry Chiral pool method: & Biology”, and category pages of sugar chains. Furthermore, The method using an easily available chiral compound as a TCI has many kinds of catalysts for asymmetric synthesis and starting material like an amino acid or sugar. introduce them in brochures such as “Asymmetric Synthesis” and Asymmetric synthesis: “Asymmetric Organocatalysts”, and other contents. The method to introduce an asymmetric point to compounds You can search our information through “asymmetric synthesis” without an asymmetric point. Syntheses using achiral as a keyword. auxiliaries are included here. Optical resolution: The method to separate a racemic compound into two ● Reactions with Chiral Auxiliaries enantiomers. The direct method using a chiral column and One of the most famous named reactions using chiral auxiliaries1) the indirect method to separate two enantiomers using is the Evans aldol reaction.2) This reaction is quite useful because optical resolving agents to convert into diastereomers are this reaction can efficiently introduce two asymmetric carbons into examples. -
Separation of the Mixtures of Chiral Compounds by Crystallization
1 Separation of the Mixtures of Chiral Compounds by Crystallization Emese Pálovics2, Ferenc Faigl1,2 and Elemér Fogassy1* 1Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 2Research Group for Organic Chemical Technology, Hungarian Academy of Sciences, Budapest, Hungary 1. Introduction Reaction of a racemic acid or base with an optically active base or acid gives a pair of diastereomeric salts. Members of this pair exhibit different physicochemical properties (e.g., solubility, melting point, boiling point, adsorbtion, phase distribution) and can be separated owing to these differences. The most important method for the separation of enantiomers is the crystallization. This is the subject of this chapter. Preparation of enantiopure (ee~100%) compounds is one of the most important aims both for industrial practice and research. Actually, the resolution of racemic compounds (1:1 mixture of molecules having mirror-imagine relationship) still remains the most common method for producing pure enantiomers on a large scale. In these cases the enantiomeric mixtures or a sort of their derivatives are separated directly. This separation is based on the fact that the enantiomeric ratio in the crystallized phase differs from the initial composition. In this way, obtaining pure enantiomers requires one or more recrystallizations. (Figure 1). The results of these crystallizations (recrystallizations) of mixtures of chiral compounds differ from those observed at the achiral compounds. Expectedly, not only the stereoisomer in excess can be crystallized, because the mixture of enantiomers (with mirror image relationship) follows the regularities established from binary melting point phase diagrams, and ternary composition solubility diagrams, respectively, as a function of the starting enantiomer proportion. -
II. Stereochemistry 5
B.Sc.(H) Chemistry Semester - II Core Course - III (CC-III) Organic Chemistry - I II. Stereochemistry 5. Physical and Chemical Properties of Stereoisomers Dr. Rajeev Ranjan University Department of Chemistry Dr. Shyama Prasad Mukherjee University, Ranchi 1 Syllabus & Coverage Syllabus II Stereochemistry: Fischer Projection, Newmann and Sawhorse Projection formulae and their interconversions. Geometrical isomerism: cis–trans and syn-anti isomerism, E/Z notations with Cahn Ingold and Prelog (CIP) rules for determining absolute configuration. Optical Isomerism: Optical Activity, Specific Rotation, Chirality/Asymmetry, Enantiomers, Molecules with two or more chiral-centres, Distereoisomers, Meso structures, Racemic mixture. Resolution of Racemic mixtures. Relative and absolute configuration: D/L and R/S designations. Coverage: 1. Types of Isomers : Comparing Structures 2. Optical Activity 3. Racemic Mixtures : Separation of Racemic Mixtures 4. Enantiomeric Excess and Optical Purity 5. Relative and Absolute Configuration 6. Physical and Chemical Properties of Stereoisomers 2 Stereochemistry Types of Isomers Dr. Rajeev Ranjan 3 Stereochemistry Determining the Relationship Between Two Non-Identical Molecules Dr. Rajeev Ranjan 4 Stereochemistry Comparing Structures: Are the structures connected the same? yes no Are they mirror images? Constitutional Isomers yes no Enantiomers Enantiomers Is there a plane of symmetry? All chiral centers will be opposite between them. yes no Meso Diastereomers superimposable Dr. Rajeev Ranjan 5 Stereochemistry Optical Activity: • The chemical and physical properties of two enantiomers are identical except in their interaction with chiral substances. • The physical property that differs is the behavior when subjected to plane-polarized light ( this physical property is often called an optical property). • Plane-polarized (polarized) light is light that has an electric vector that oscillates in a single plane. -
Effect of the Enantiomeric Ratio of Eutectics on the Results and Products of the Reactions Proceeding with the Participation Of
Perspective Effect of the Enantiomeric Ratio of Eutectics on the Results and Products of the Reactions Proceeding with the Participation of Enantiomers and Enantiomeric Mixtures Emese Pálovics *, Dorottya Fruzsina Bánhegyi and Elemér Fogassy Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, 1521 Budapest, Hungary; [email protected] (D.F.B.); [email protected] (E.F.) * Correspondence: [email protected]; Tel.: +36-1-4632101 Received: 3 August 2020; Accepted: 14 September 2020; Published: 21 September 2020 Abstract: This perspective is focused on the main parameters determining the results of crystallization of enantiomers or enantiomeric mixtures. It was shown that the ratio of supramolecular and helical associations depends on the eutectic composition of the corresponding enantiomeric mixture. The M and P ratios together with the self-disproportionation (SDE) of enantiomers define the reaction of the racemic compound with the resolving agent. Eventually, each chiral molecule reacts with at least two conformers with different degrees of M and P helicity. The combined effect of the configuration, charge distribution, constituent atoms, bonds, flexibility, and asymmetry of the molecules influencing their behavior was also summarized. Keywords: chiral molecules; enantiomeric separation; self-disproportionation of enantiomers; supramolecular associations; helical structure; eutectic composition 1. Introduction The preparation of asymmetric (chiral) compounds (enantiomers) is one of the main goals of research, industry and medicine. The preparation of a given enantiomer is possible in several ways, for example by selective synthesis, which requires the separation of the chiral catalyst or the enantiomers of the racemic compound, and in which case a resolving agent (like a chiral catalyst) may be required. -
Enantioselective Synthesis of the (1S,5R)-Enantiomer of Litseaverticillols a and B
Biosci. Biotechnol. Biochem., 70 (10), 2564–2566, 2006 Note Enantioselective Synthesis of the (1S,5R)-Enantiomer of Litseaverticillols A and B y Akira MORITA, Hiromasa KIYOTA, and Shigefumi KUWAHARA Laboratory of Applied Bioorganic Chemistry, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan Received May 8, 2006; Accepted May 31, 2006; Online Publication, October 7, 2006 [doi:10.1271/bbb.60253] An enantioselective synthesis of the (1S,5R)-enan- which have recently culminated in the first enantiose- tiomer of litseaverticillols A and B was accomplished in lective total synthesis of (1R,5S)-(À)-1 and (1R,5S)-(À)- line with our previously reported synthetic pathway for 2.4) In this note, we describe the synthesis of their their (1R,5S)-enantiomer. The use of ‘‘EtSCeCl2’’ pre- enantiomers directed toward an evaluation of the differ- pared from EtSLi and CeCl3, instead of previously ence in biological activity between the enantiomers of employed EtSLi itself, for the formation of thiol ester litseaverticillols A and B. intermediates prevented any undesirable epimerization Our synthesis of (1S,5R)-1 and (1S,5R)-2 basically occurring in the process. followed our previous synthesis of their corresponding enantiomers, (1R,5S)-1 and (1R,5S)-2, respectively,4) Key words: litseaverticillol; enantioselective synthesis; except that (R)-4-benzyloxazolidin-2-one was employed sesquiterpenoid; anti-HIV as the source of chirality, instead of its (S)-form used in the previous synthesis. Homogeranic -
Lecture 3: Stereochemistry and Drugs Key Objectives: 1
Lecture 3: Stereochemistry and drugs Key objectives: 1. Be able to explain the role of stereochemistry in drug action or metabolism 2. Be able to identify a chiral center (or centers) in a drug 3. Be able to explain the difference between enantiomers and diastereomers Value of chirality and stereochemistry: Chirality as expressed through stereoisomers increases the specificity of molecule recognition and signaling. Like a key in a lock, or a hand in a glove. Some useful definitions: Chirality (and chiral centers): An object (such as a molecule) that is asymmetric and therefore not superimposable on its own image. Chiral centers are the most common features within molecules that give rise to chirality. Stereoisomer: A molecule that possesses at least one chiral center (or center of chirality). Enantiomers: A type of stereoisomer that exists in mirror image forms. See Figure 1. Diastereomers: A type of stereoisomer that possesses more than one chiral center. Stereospecific: A term used to describe a stereochemical property that one isomer possesses but the other does not. For example, the stereospecific metabolism of the S-enantiomer of a compound by an enzyme but the R-enantiomer is not metabolized by that enzyme. Stereoselective: A term used to describe a stereochemical property that is shared by both stereoisomers, but the property is greater in one isomer than the other. For example, the stereoselective binding of the R-enantiomer for a receptor indicates that the S-enantiomer also binds but not as avidly as the R-enantiomer. Enantiomers Figure 1: For enantiomers, many times we use the example of our left and right hands to demonstrate their asymmetry. -
Cross-Linked Protein Crystal Technology in Bioseparation and Biocatalytic Applications
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Aaltodoc Helsinki University of Technology, Department of Chemical Technology Technical Biochemistry Report 1/2004 Espoo 2004 TKK-BE-8 CROSS-LINKED PROTEIN CRYSTAL TECHNOLOGY IN BIOSEPARATION AND BIOCATALYTIC APPLICATIONS Antti Vuolanto Dissertation for the degree of Doctor in Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Auditorium KE 2 (Komppa Auditorium) at Helsinki University of Technology (Espoo, Finland) on the 20th of August, 2004, at 12 noon. Helsinki University of Technology Department of Chemical Technology Laboratory of Bioprocess Engineering Teknillinen korkeakoulu Kemian osasto Bioprosessitekniikan laboratorio Distribution: Helsinki University of Technology Laboratory of Bioprocess Engineering P.O. Box 6100 FIN-02015 HUT Tel. +358-9-4512541 Fax. +358-9-462373 E-mail: [email protected] ©Antti Vuolanto ISBN 951-22-7176-1 (printed) ISBN 951-22-7177-X (pdf) ISSN 0359-6621 Espoo 2004 Vuolanto, Antti. Cross-linked protein crystal technology in bioseparation and biocatalytic applications. Espoo 2004, Helsinki University of Technology. Abstract Chemical cross-linking of protein crystals form an insoluble and active protein matrix. Cross-linked protein crystals (CLPCs) have many excellent properties including high volumetric activity and stability. In this thesis CLPC technology was studied in bioseparation and biocatalytic applications. A novel immunoaffinity separation material, cross-linked antibody crystals (CLAC), was developed in this thesis for enantiospecific separation of a chiral drug, finrozole. Previously, the preparation of an antibody Fab fragment ENA5His capable of enantiospecific affinity separation of the chiral drug has been described. -
Diastereomers Diastereomers
Diastereomers Diastereomers: Stereoisomers that are not mirror images. enantiomer (R) (S) (S) (R) diastereomers diastereomer diastereomer enantiomer (R) (S) (R) (S) Diastereomers Diastereomers: Stereoisomers that are not mirror images. (R) enantiomer (S) (S) (R) diastereomer To draw the enantiomer of a molecule with chiral centers, invert stereochemistry at all chiral centers. (R) To draw a diastereomer of a molecule (R) with chiral centers, invert stereochemistry at only some chiral centers. Meso Compounds Meso: A molecule that contains chiral centers, but is achiral. 3 Are these molecules chiral? (R) (S) (These are diff eren t f rom th e 3 molecules I just showed; they have 2 -Cl’s, rather than 1 -Cl & 1 -OH. enantiomer (R) (S) (R) (S) These molecules are chiral mirror images of one another. (R,R) and (S,S) are not the same. Meso Compounds Meso: A molecule that contains chiral centers, but is achiral. 3 enantiomer ? (R) (S) (S) (R) no! 3 same molecule! enantiomer (R) (S) (R) (S) Meso Compounds Meso: A molecule that contains chiral centers, but is achiral. 3 enantiomer ? (R) (S) (S) (R) no! 3 same molecule! If a molecule • contains the same number of (R) and (S) stereocenters, and • those stereocenters have identical groups attached, then the molecule is achiral and meso. Meso Compounds Meso: A molecule that contains chiral centers, but is achiral. 3 same molecule (R) (S) (S) (R) 3 meso diastereomers meso diastereomer diastereomer enantiomer (R) (S) (R) (S) chiral chiral Properties of Enantiomers Most physical properties of enantiomers are identical. diethyl-(R,R)-tartrate diethyl-(S,S)-tartrate boiling point 280 °C 280 °C melting point 19 °C 19 °C density 1.204 g/mL 1.204 g/mL refractive index 1.447 1.447 i.e., chirality does not affect most physical properties. -
Page 1 of 108 RSC Advances
RSC Advances This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. This Accepted Manuscript will be replaced by the edited, formatted and paginated article as soon as this is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. www.rsc.org/advances Page 1 of 108 RSC Advances Applications of oxazolidinones as chiral auxiliaries in the asymmetric alkylation reaction applied to total synthesis Majid M. Heravi,* Vahideh Zadsirjan, Behnaz Farajpour Department of Chemistry, School of Science, Alzahra University, Vanak, Tehran, Iran Email: [email protected] Abstract Various chiral oxazolidinones (Evans' oxazolidinones) have been employed as effective chiral auxiliaries in the asymmetric alkylation of different enolates. This strategy has been found promising and successful when used as key step (steps) in the total synthesis of several biologically active natural products. In this report, we try to underscore the applications of Manuscript oxazolidinones as chiral auxiliary in asymmetric alkylation, and particularly in crucial chiral inducing steps in the total synthesis of natural products, showing biological activities. -
The Racemate-To-Homochiral Approach to Crystal Engineering Via Chiral Symmetry-Breaking
CrystEngComm The Racemate -to -Homochiral Approach to Crystal Engineering via Chiral Symmetry-Breaking Journal: CrystEngComm Manuscript ID: CE-HIG-02-2015-000402.R1 Article Type: Highlight Date Submitted by the Author: 04-Apr-2015 Complete List of Authors: An, Guanghui; Heilongjiang University, School of Chemistry and Materials Science Yan, Pengfei; Heilongjiang University, School of Chemistry and Materials Science Sun, Jingwen; Heilongjiang University, School of Chemistry and Materials Science Li, Yuxin; School of Chemsitry and Materials Science of Heilongjiang University, Yao, Xu; Heilongjiang University, School of Chemistry and Materials Science Li, Guangming; School of Chemsitry and Materials Science of Heilongjiang University, Page 1 of 12Journal Name CrystEngComm Dynamic Article Links ► Cite this: DOI: 10.1039/c0xx00000x www.rsc.org/xxxxxx ARTICLE TYPE The Racemate-to-Homochiral Approach to Crystal Engineering via Chiral Symmetry-Breaking Guanghui An, a Pengfei Yan, a Jingwen Sun, a Yuxin Li, a Xu Yao, a Guangming Li,* a Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX 5 DOI: 10.1039/b000000x The racemate-to-homochiral approach is to transform or separate the racemic mixture into homo chiral compounds. This protocol, if without an external chiral source, is categorized into chiral symmetry- breaking. The resolution processes without chiral induction are highly important for the investigation on the origin of homochirality in life, pharmaceutical synthesis, chemical industrial and material science. 10 Besides the study on the models and mechanisms to explain the racemate-to-homochiral approach which may give the probable origin of homochirality in life, the recent developments in this field have been plotted towards the separation of enantiomers for the synthesis of pharmaceuticals, chiral chemicals. -
Enantiomers & Diastereomers
Chapter 5 Stereochemistry Chiral Molecules Ch. 5 - 1 1. Chirality & Stereochemistry An object is achiral (not chiral) if the object and its mirror image are identical Ch. 5 - 2 A chiral object is one that cannot be superposed on its mirror image Ch. 5 - 3 1A. The Biological Significance of Chirality Chiral molecules are molecules that cannot be superimposable with their mirror images O O ● One enantiomer NH causes birth defects, N O the other cures morning sickness O Thalidomide Ch. 5 - 4 HO NH HO OMe Tretoquinol OMe OMe ● One enantiomer is a bronchodilator, the other inhibits platelet aggregation Ch. 5 - 5 66% of all drugs in development are chiral, 51% are being studied as a single enantiomer Of the $475 billion in world-wide sales of formulated pharmaceutical products in 2008, $205 billion was attributable to single enantiomer drugs Ch. 5 - 6 2. Isomerisom: Constitutional Isomers & Stereoisomers 2A. Constitutional Isomers Isomers: different compounds that have the same molecular formula ● Constitutional isomers: isomers that have the same molecular formula but different connectivity – their atoms are connected in a different order Ch. 5 - 7 Examples Molecular Constitutional Formula Isomers C4H10 and Butane 2-Methylpropane Cl Cl C3H7Cl and 1-Chloropropane 2-Chloropropane Ch. 5 - 8 Examples Molecular Constitutional Formula Isomers CH O CH C H O OH and 3 3 2 6 Ethanol Methoxymethane O OCH and 3 C H O OH 4 8 2 O Butanoic acid Methyl propanoate Ch. 5 - 9 2B. Stereoisomers Stereoisomers are NOT constitutional isomers Stereoisomers have their atoms connected in the same sequence but they differ in the arrangement of their atoms in space.