1. The document discusses chirality and its importance in the origin of life. It describes theories for how homochirality first arose, including symmetry breaking, autocatalytic amplification, and transmission of chirality through solid and solution phases.
2. Specific models are examined, such as Frank's autocatalytic and Soai reaction models, chiral amnesia in organic solids, and eutectic solutions providing homochirality.
3. These chemical models provide plausible pathways for the evolution of homochirality in nature and will aid understanding the origins of biological organization and engineering novel biological systems.
Discussion on photolysis, Norrish rearrangement, photolysis of azo compounds, isomerization and rearrangement, Fries rearrangement, chemiluminescence and bioluminescence
This document summarizes research on the quenching of the luminescent excited state of the compound Ru(bpy)3
2+ by silver nanoparticles (Ag-NPs). It was found that Ag-NPs are effective quenchers of Ru(bpy)3
2+ emission. Stern-Volmer analysis revealed a large constant, indicating a static rather than dynamic quenching mechanism involving formation of an electrostatic complex between Ru(bpy)3
2+ and Ag-NPs. Spectroscopic titration showed a new absorption peak and leveling off at a 500:1 molar ratio of Ru(bpy)3
2+ to Ag-NPs, supporting complex formation as the
Thermal reactions involve absorption or evolution of heat, while photochemical reactions require light to occur. Thermochemical reactions can take place in dark conditions, while photochemical reactions only occur in the presence of light. Temperature significantly affects thermochemical reaction rates, while light intensity mainly influences photochemical reaction rates. The free energy change of a thermochemical reaction is always negative, but a photochemical reaction's free energy change may not be negative. Photochemical reactions involve electronic excitation from light absorption. Excited states can undergo chemical reactions or transfer energy through intersystem crossing to more stable triplet states. Photochemical reactions include photoreduction, photoaddition, and photo-rearrangement reactions of carbonyl compounds and alkenes.
The document discusses pericyclic reactions and the Woodward-Hoffmann rules for predicting their stereochemistry. It begins by defining pericyclic reactions as concerted reactions where bonds are formed or broken in a cyclic transition state. It then provides examples of different types of pericyclic reactions, including electrocyclizations, cycloadditions, and sigmatropic rearrangements. The Woodward-Hoffmann theory is explained, showing how it can be used to predict whether a reaction will proceed with antarafacial conrotation or suprafacial disrotation based on whether the reaction is thermally or photochemically induced. Specific examples like cyclobutene formation and the Diels-Alder reaction are analyzed in
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
photo redox reactions
The document discusses the nuclear Overhauser effect (NOE), which occurs when two protons are in close proximity within a molecule. Irradiating one proton perturbs its spin distribution and affects the relaxation of the other nearby proton. This causes the intensity of the other proton's signal to increase or decrease, indicating their proximity. The NOE provides information about molecular geometry without requiring coupling between nuclei and can reveal which protons are near each other in a structure.
This document summarizes key aspects of palladium-catalyzed cross-coupling reactions, with a focus on the Heck reaction and its mechanisms and applications. The Heck reaction involves the coupling of alkenyl or aryl halides with alkenes, catalyzed by palladium. The mechanism proceeds through oxidative addition, transmetalation, and reductive elimination steps. The document discusses factors that determine regioselectivity and provides examples of the Heck reaction in total syntheses of natural products like dehydrotubifoline, capnellene, and taxol. It also describes domino and intramolecular Heck reactions and summarizes the related Stille coupling reaction.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors such as the solvent, substituents on the carbonyl compound or alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize various natural products and allows formation of oxetane rings, which are present in several biologically active compounds.
Discussion on photolysis, Norrish rearrangement, photolysis of azo compounds, isomerization and rearrangement, Fries rearrangement, chemiluminescence and bioluminescence
This document summarizes research on the quenching of the luminescent excited state of the compound Ru(bpy)3
2+ by silver nanoparticles (Ag-NPs). It was found that Ag-NPs are effective quenchers of Ru(bpy)3
2+ emission. Stern-Volmer analysis revealed a large constant, indicating a static rather than dynamic quenching mechanism involving formation of an electrostatic complex between Ru(bpy)3
2+ and Ag-NPs. Spectroscopic titration showed a new absorption peak and leveling off at a 500:1 molar ratio of Ru(bpy)3
2+ to Ag-NPs, supporting complex formation as the
Thermal reactions involve absorption or evolution of heat, while photochemical reactions require light to occur. Thermochemical reactions can take place in dark conditions, while photochemical reactions only occur in the presence of light. Temperature significantly affects thermochemical reaction rates, while light intensity mainly influences photochemical reaction rates. The free energy change of a thermochemical reaction is always negative, but a photochemical reaction's free energy change may not be negative. Photochemical reactions involve electronic excitation from light absorption. Excited states can undergo chemical reactions or transfer energy through intersystem crossing to more stable triplet states. Photochemical reactions include photoreduction, photoaddition, and photo-rearrangement reactions of carbonyl compounds and alkenes.
The document discusses pericyclic reactions and the Woodward-Hoffmann rules for predicting their stereochemistry. It begins by defining pericyclic reactions as concerted reactions where bonds are formed or broken in a cyclic transition state. It then provides examples of different types of pericyclic reactions, including electrocyclizations, cycloadditions, and sigmatropic rearrangements. The Woodward-Hoffmann theory is explained, showing how it can be used to predict whether a reaction will proceed with antarafacial conrotation or suprafacial disrotation based on whether the reaction is thermally or photochemically induced. Specific examples like cyclobutene formation and the Diels-Alder reaction are analyzed in
more chemistry contents are available
1. pdf file on Termmate: https://www.termmate.com/rabia.aziz
2. YouTube: https://www.youtube.com/channel/UCKxWnNdskGHnZFS0h1QRTEA
3. Facebook: https://web.facebook.com/Chemist.Rabia.Aziz/
4. Blogger: https://chemistry-academy.blogspot.com/
photo redox reactions
The document discusses the nuclear Overhauser effect (NOE), which occurs when two protons are in close proximity within a molecule. Irradiating one proton perturbs its spin distribution and affects the relaxation of the other nearby proton. This causes the intensity of the other proton's signal to increase or decrease, indicating their proximity. The NOE provides information about molecular geometry without requiring coupling between nuclei and can reveal which protons are near each other in a structure.
This document summarizes key aspects of palladium-catalyzed cross-coupling reactions, with a focus on the Heck reaction and its mechanisms and applications. The Heck reaction involves the coupling of alkenyl or aryl halides with alkenes, catalyzed by palladium. The mechanism proceeds through oxidative addition, transmetalation, and reductive elimination steps. The document discusses factors that determine regioselectivity and provides examples of the Heck reaction in total syntheses of natural products like dehydrotubifoline, capnellene, and taxol. It also describes domino and intramolecular Heck reactions and summarizes the related Stille coupling reaction.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors such as the solvent, substituents on the carbonyl compound or alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize various natural products and allows formation of oxetane rings, which are present in several biologically active compounds.
13C NMR gives distinct signals for each non-equivalent carbon atom based on its chemical environment. It has a wider chemical shift range than 1H NMR, allowing for easier separation of signals. However, 13C NMR spectra are complicated by weak signals due to the low natural abundance of 13C. Modern Fourier transform NMR techniques have helped overcome this issue. Proton-decoupled 13C NMR provides simple spectra with one peak per carbon, while proton-coupled spectra show splitting patterns indicating directly bonded protons. 13C NMR finds numerous applications in
The document provides an overview of basic principles of photochemistry. It discusses key concepts like photochemical processes, importance of photochemistry, terminology used in photochemistry including charge transfer transitions, multiplicity, internal conversion and more. It also explains photochemical reaction processes like dissociation, direct reactions, isomerization, energy transfer and quenching. Laws of photochemistry, quantum yield, Jablonski diagram, Franck-Condon principle, electronic transitions, mechanisms of photosensitization and applications of photosensitization are summarized.
Ryoji Noyori was born in 1938 in Japan and won the Nobel Prize in Chemistry in 2001 for his work developing chiral catalysts for asymmetric hydrogenation reactions. Some of his key accomplishments include developing ruthenium and rhodium complexes with BINAP ligands that allow for the asymmetric hydrogenation of alkenes. This has enabled the commercial production of drugs like naproxen. He has also developed catalyst systems for other asymmetric reactions and his methods are used industrially, such as for the production of menthol.
The coupling constant is the distance between peaks in a multiplet in NMR spectroscopy. It is measured in Hertz and does not depend on external magnetic field strength. The value of the coupling constant provides information to distinguish multiplets and can indicate structural features like cis/trans isomers. Coupling occurs between protons close in space, known as geminal, vicinal, and sometimes long-range coupling over several bonds. The coupling constant is affected by factors like bond angle, dihedral angle, and electronegativity of substituents.
This document discusses various 2D NMR techniques used in pharmaceutical analysis including COSY, NOESY, HSQC, HMBC, and INADEQUATE. It explains the principles and applications of each technique. COSY identifies protons that are coupled through bonds, while NOESY identifies protons that are spatially close. HSQC and HMBC correlate 1H and 13C signals to determine connectivity. INADEQUATE directly shows 13C-13C connectivity but has low sensitivity. Together, these 2D NMR methods provide detailed structural information about pharmaceutical compounds.
This document provides an overview of asymmetric synthesis and strategies for achieving asymmetric induction. It defines asymmetric synthesis as a reaction that yields predominantly one chiral stereoisomer. It discusses different strategies for asymmetric induction, including using a chiral auxiliary, chiral reagent/catalyst, or starting with a chiral pool substrate. Specific examples are provided of chiral reagents like BINOL-H and Alpine borane that can be used to selectively reduce prochiral ketones. Chiral ligands like DIOP and CHIRAPHOS that are used with metal catalysts for asymmetric hydrogenation are also described.
This document discusses optical rotatory dispersion (ORD), which is defined as the rate of change of specific rotation with a change in wavelength. ORD is used to determine the structures of carbonyl compounds. Key points covered include: the principles of plane polarized light, optical activity, specific rotation, and circular birefringence; factors that affect specific rotation; Cotton effects and curves; and the octant rule for establishing absolute configuration from ORD data.
This document provides a tabular survey and overview of various organocatalysts used in asymmetric organocatalysis reactions, including their reaction scopes and commercial availabilities. It discusses how L-proline and other amino acids like L-phenylalanine are commonly used economical organocatalysts that are readily available. It also outlines how cinchona alkaloids are widely used organocatalysts that are commercially available. In general, the document surveys different organocatalysts and their applications in asymmetric reactions.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors like the solvent, substituents on the carbonyl and alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize biologically active oxetane-containing compounds and to construct more complex carbocyclic and heterocyclic ring systems.
The document discusses various photooxidation and photoreduction reactions in organic synthesis. It begins by introducing photochemistry and defining related terms. It then provides examples of photoreduction of ketones and aromatic hydrocarbons. Examples of photooxidation reactions include the conversion of trans-stilbene to phenanthrene and the synthesis of benzoic acids via aerobic photooxidation. The document also describes the mechanism and advantages of using a CdIn2S4 photocatalyst for selective photosynthesis of organic aromatic compounds under visible light.
A. 13C NMR spectroscopy provides information about carbon structures in organic compounds. It measures the small differences in magnetic field strength needed for carbon nuclei to resonate. These differences are reported in parts per million (ppm) relative to tetramethylsilane (TMS) as a standard. Factors like electronegativity, hybridization, and hydrogen bonding affect the chemical shift values. 13C NMR has applications in metabolic studies and industrial analyses of solids.
Reactions in solution [ solution kinetics]ChithraNair13
The document discusses reaction kinetics in solution, including how the solvent cage effect can influence reaction rates by temporarily trapping reactant molecules and allowing multiple collisions. It also compares reaction rates and mechanisms between gas phase and solution reactions, and examines how factors like solvent polarity, solvation, and dielectric constant can impact the rates of different classes of reactions in solution, such as diffusion-controlled or activation-controlled processes. The volume of activation is also defined as relating to the change in partial molar volumes between reactants and the transition state.
1. Cycloaddition reactions involve the addition of two pi systems to form a cyclic product with two new sigma bonds and two fewer pi bonds. They can occur suprafacially or antrafacially.
2. The Diels-Alder reaction is a common [4+2] cycloaddition between a diene and an alkene. The sign of the frontier orbitals must match for the reaction to be thermally or photochemically allowed.
3. The diene typically has electron-donating groups and the dienophile electron-withdrawing groups for efficient Diels-Alder reactions. The stereochemistry of substituents is maintained in the product.
This document discusses metathesis reactions and their applications in organic synthesis. It begins with definitions and examples of different types of metathesis reactions including alkene, alkyne, and enyne metathesis. It then covers the key catalysts used, such as Grubbs and Schrock catalysts, as well as the 2005 Nobel Prize awarded for the development of metathesis reactions. The document concludes by outlining several important applications of metathesis in synthesizing biologically active compounds and natural products.
The document discusses two-dimensional nuclear magnetic resonance spectroscopy (2D NMR). 2D NMR provides more structural information about molecules than 1D NMR. There are several types of 2D NMR experiments that provide different information, including COSY, TOCSY, HSQC, and NOESY. These experiments establish correlations between nuclei that are directly bonded or spatially close. 2D NMR is useful for determining molecular structures, especially of complex biomolecules like proteins.
A carbene is any neutral carbon species which contains a non-bonding valance pair of electrons.
Contributed by Alison Brown & Nathan Buehler, Undergraduates, University of Utah
This document provides an overview of asymmetric synthesis and stereochemistry. It begins with definitions of stereoisomers including enantiomers and diastereomers. It then discusses how asymmetric synthesis creates new chiral centers, giving unequal amounts of stereoisomers. Key terms like enantiomeric excess and methods for determining ee are explained. The document outlines different types of asymmetric synthesis controlled by the substrate, auxiliary, reagent or catalyst. It also defines stereoselective and stereospecific reactions. The principles of asymmetric induction and double diastereoselection/asymmetric induction are covered. Recommended books on the topic are provided.
The document discusses asymmetric synthesis, which is the synthesis of a single enantiomer of a chiral compound. It covers retrosynthetic analysis, using disconnections to plan multi-step syntheses. Functional group interconversion and two-group disconnections are recommended to avoid chemoselectivity problems. Chiral auxiliaries and resolving agents can be used to separate enantiomers. Chiral auxiliaries induce diastereoselectivity through steric effects to yield a single enantiomer of the product. An example reaction is given to synthesize (S)-1-(pyridine-3-yl)propan-1-ol using a chiral catalyst.
13C NMR gives distinct signals for each non-equivalent carbon atom based on its chemical environment. It has a wider chemical shift range than 1H NMR, allowing for easier separation of signals. However, 13C NMR spectra are complicated by weak signals due to the low natural abundance of 13C. Modern Fourier transform NMR techniques have helped overcome this issue. Proton-decoupled 13C NMR provides simple spectra with one peak per carbon, while proton-coupled spectra show splitting patterns indicating directly bonded protons. 13C NMR finds numerous applications in
The document provides an overview of basic principles of photochemistry. It discusses key concepts like photochemical processes, importance of photochemistry, terminology used in photochemistry including charge transfer transitions, multiplicity, internal conversion and more. It also explains photochemical reaction processes like dissociation, direct reactions, isomerization, energy transfer and quenching. Laws of photochemistry, quantum yield, Jablonski diagram, Franck-Condon principle, electronic transitions, mechanisms of photosensitization and applications of photosensitization are summarized.
Ryoji Noyori was born in 1938 in Japan and won the Nobel Prize in Chemistry in 2001 for his work developing chiral catalysts for asymmetric hydrogenation reactions. Some of his key accomplishments include developing ruthenium and rhodium complexes with BINAP ligands that allow for the asymmetric hydrogenation of alkenes. This has enabled the commercial production of drugs like naproxen. He has also developed catalyst systems for other asymmetric reactions and his methods are used industrially, such as for the production of menthol.
The coupling constant is the distance between peaks in a multiplet in NMR spectroscopy. It is measured in Hertz and does not depend on external magnetic field strength. The value of the coupling constant provides information to distinguish multiplets and can indicate structural features like cis/trans isomers. Coupling occurs between protons close in space, known as geminal, vicinal, and sometimes long-range coupling over several bonds. The coupling constant is affected by factors like bond angle, dihedral angle, and electronegativity of substituents.
This document discusses various 2D NMR techniques used in pharmaceutical analysis including COSY, NOESY, HSQC, HMBC, and INADEQUATE. It explains the principles and applications of each technique. COSY identifies protons that are coupled through bonds, while NOESY identifies protons that are spatially close. HSQC and HMBC correlate 1H and 13C signals to determine connectivity. INADEQUATE directly shows 13C-13C connectivity but has low sensitivity. Together, these 2D NMR methods provide detailed structural information about pharmaceutical compounds.
This document provides an overview of asymmetric synthesis and strategies for achieving asymmetric induction. It defines asymmetric synthesis as a reaction that yields predominantly one chiral stereoisomer. It discusses different strategies for asymmetric induction, including using a chiral auxiliary, chiral reagent/catalyst, or starting with a chiral pool substrate. Specific examples are provided of chiral reagents like BINOL-H and Alpine borane that can be used to selectively reduce prochiral ketones. Chiral ligands like DIOP and CHIRAPHOS that are used with metal catalysts for asymmetric hydrogenation are also described.
This document discusses optical rotatory dispersion (ORD), which is defined as the rate of change of specific rotation with a change in wavelength. ORD is used to determine the structures of carbonyl compounds. Key points covered include: the principles of plane polarized light, optical activity, specific rotation, and circular birefringence; factors that affect specific rotation; Cotton effects and curves; and the octant rule for establishing absolute configuration from ORD data.
This document provides a tabular survey and overview of various organocatalysts used in asymmetric organocatalysis reactions, including their reaction scopes and commercial availabilities. It discusses how L-proline and other amino acids like L-phenylalanine are commonly used economical organocatalysts that are readily available. It also outlines how cinchona alkaloids are widely used organocatalysts that are commercially available. In general, the document surveys different organocatalysts and their applications in asymmetric reactions.
The Paternò-Büchi reaction involves the photochemical reaction between a carbonyl compound and an alkene to form an oxetane ring. This reaction was first reported in 1909 by Paternò and Chieffi. Several mechanisms are possible, including those involving a diradical intermediate or photoinduced electron transfer. The reaction shows regioselectivity, site selectivity, and stereoselectivity that depend on factors like the solvent, substituents on the carbonyl and alkene, and temperature. The Paternò-Büchi reaction has been used to synthesize biologically active oxetane-containing compounds and to construct more complex carbocyclic and heterocyclic ring systems.
The document discusses various photooxidation and photoreduction reactions in organic synthesis. It begins by introducing photochemistry and defining related terms. It then provides examples of photoreduction of ketones and aromatic hydrocarbons. Examples of photooxidation reactions include the conversion of trans-stilbene to phenanthrene and the synthesis of benzoic acids via aerobic photooxidation. The document also describes the mechanism and advantages of using a CdIn2S4 photocatalyst for selective photosynthesis of organic aromatic compounds under visible light.
A. 13C NMR spectroscopy provides information about carbon structures in organic compounds. It measures the small differences in magnetic field strength needed for carbon nuclei to resonate. These differences are reported in parts per million (ppm) relative to tetramethylsilane (TMS) as a standard. Factors like electronegativity, hybridization, and hydrogen bonding affect the chemical shift values. 13C NMR has applications in metabolic studies and industrial analyses of solids.
Reactions in solution [ solution kinetics]ChithraNair13
The document discusses reaction kinetics in solution, including how the solvent cage effect can influence reaction rates by temporarily trapping reactant molecules and allowing multiple collisions. It also compares reaction rates and mechanisms between gas phase and solution reactions, and examines how factors like solvent polarity, solvation, and dielectric constant can impact the rates of different classes of reactions in solution, such as diffusion-controlled or activation-controlled processes. The volume of activation is also defined as relating to the change in partial molar volumes between reactants and the transition state.
1. Cycloaddition reactions involve the addition of two pi systems to form a cyclic product with two new sigma bonds and two fewer pi bonds. They can occur suprafacially or antrafacially.
2. The Diels-Alder reaction is a common [4+2] cycloaddition between a diene and an alkene. The sign of the frontier orbitals must match for the reaction to be thermally or photochemically allowed.
3. The diene typically has electron-donating groups and the dienophile electron-withdrawing groups for efficient Diels-Alder reactions. The stereochemistry of substituents is maintained in the product.
This document discusses metathesis reactions and their applications in organic synthesis. It begins with definitions and examples of different types of metathesis reactions including alkene, alkyne, and enyne metathesis. It then covers the key catalysts used, such as Grubbs and Schrock catalysts, as well as the 2005 Nobel Prize awarded for the development of metathesis reactions. The document concludes by outlining several important applications of metathesis in synthesizing biologically active compounds and natural products.
The document discusses two-dimensional nuclear magnetic resonance spectroscopy (2D NMR). 2D NMR provides more structural information about molecules than 1D NMR. There are several types of 2D NMR experiments that provide different information, including COSY, TOCSY, HSQC, and NOESY. These experiments establish correlations between nuclei that are directly bonded or spatially close. 2D NMR is useful for determining molecular structures, especially of complex biomolecules like proteins.
A carbene is any neutral carbon species which contains a non-bonding valance pair of electrons.
Contributed by Alison Brown & Nathan Buehler, Undergraduates, University of Utah
This document provides an overview of asymmetric synthesis and stereochemistry. It begins with definitions of stereoisomers including enantiomers and diastereomers. It then discusses how asymmetric synthesis creates new chiral centers, giving unequal amounts of stereoisomers. Key terms like enantiomeric excess and methods for determining ee are explained. The document outlines different types of asymmetric synthesis controlled by the substrate, auxiliary, reagent or catalyst. It also defines stereoselective and stereospecific reactions. The principles of asymmetric induction and double diastereoselection/asymmetric induction are covered. Recommended books on the topic are provided.
The document discusses asymmetric synthesis, which is the synthesis of a single enantiomer of a chiral compound. It covers retrosynthetic analysis, using disconnections to plan multi-step syntheses. Functional group interconversion and two-group disconnections are recommended to avoid chemoselectivity problems. Chiral auxiliaries and resolving agents can be used to separate enantiomers. Chiral auxiliaries induce diastereoselectivity through steric effects to yield a single enantiomer of the product. An example reaction is given to synthesize (S)-1-(pyridine-3-yl)propan-1-ol using a chiral catalyst.
This document provides an overview of various spectroscopy techniques used in chemistry including UV-Visible spectroscopy, infrared spectroscopy, and NMR spectroscopy. It discusses key concepts in stereochemistry and types of organic reactions such as elimination and substitution reactions. Specifically, it covers the principles, instrumentation, and applications of UV-Visible spectroscopy including Beer's law and factors that affect accuracy and precision. It also discusses infrared spectroscopy techniques including instrumentation, sources, detectors, and sample handling methods like ATR and FT-IR.
1. Chiral chromatography refers to the separation of enantiomers using a chiral stationary phase in HPLC. Approximately 60% of pharmaceutical drugs are chiral.
2. There are several types of chiral stationary phases used for separation, including polymer-based carbohydrates, Pirkle phases, cyclodextrins, chirobiotic phases, and protein-based phases. Each type interacts differently with enantiomers through mechanisms like hydrogen bonding and pi-pi interactions.
3. Being able to separate enantiomers is important for drug development since individual enantiomers may have different biological effects and safety profiles. Chromatographic techniques allow for the analysis and purification of single enantiomers.
The document discusses the topic of stereochemistry. It defines stereoisomers as isomers that have the same molecular formula and structural formula but differ in the spatial arrangement of atoms. There are two main types of stereoisomers - configurational isomers and conformational isomers. Configurational isomers cannot be interconverted without breaking chemical bonds, while conformational isomers can rapidly interconvert. Specific examples of configurational isomers discussed are enantiomers, which are non-superimposable mirror images, and geometric isomers, which differ in geometry about a double bond. Methods for separating enantiomers like formation of diastereomeric salts are also summarized.
This document discusses stereochemistry and chirality in drug molecules. It defines stereoisomers as molecules with the same bonding but different spatial arrangements, and enantiomers as two stereoisomers that are mirror images of each other. Chiral drugs can exist as single enantiomers or as racemic mixtures of both. Using single enantiomers is preferable since biological interactions may differ for each form. The document provides examples of naming enantiomers and determining chirality and stereoisomers in molecules.
This document provides information on various laboratory techniques used in organic chemistry reactions and analysis. It discusses common solvents, how to remove moisture from solvents using molecular sieves, and methods to monitor reactions including changes in color, gas evolution, and thin layer chromatography. Isolation techniques like recrystallization, extraction, and column chromatography are also covered. The document explains characterization methods such as NMR, IR, UV-Vis, and mass spectrometry. It provides details on spectroscopy, interpreting IR spectra, and conditions for IR absorption. Storage procedures for solid and liquid products are also mentioned.
This document discusses chiral chromatography and methods for chiral separation. It begins with introducing key concepts such as isomers, chirality, enantiomers, and diastereomers. It then discusses various types of chiral chromatography techniques including chiral HPLC. Chiral HPLC uses chiral stationary phases or chiral mobile phase additives to achieve separation of enantiomers through formation of transient diastereomers on the column. Key factors that influence chiral separations by HPLC are discussed such as temperature, three-point interactions, and types of chiral columns.
This document provides an overview of the course "Organic Chemistry: Fundamentals and Applications". The 27-lecture course covers basic organic chemistry concepts, functional groups, drugs, chemistry of odors and flavors, photochemistry, organic materials, green chemistry, catalysis, enzymes, and solid phase synthesis. It also details the content that will be covered regarding molecular structures and stereochemistry, including conformational analysis, stereoisomerism, chirality, diastereomers, and the properties dependent on molecular shapes and functional groups. The document lists common organic reaction types and provides examples of nucleophilic substitution reactions in biological systems and drug synthesis.
Analyzing Aggregates of Different Sizes and Types: SEC vs. Analytical Ultrace...KBI Biopharma
This document discusses different methods for analyzing protein aggregates of various sizes and types, including size exclusion chromatography (SEC), analytical ultracentrifugation, and light scattering. It notes some limitations of SEC, including that changes in solvent conditions can alter aggregate distributions and larger aggregates may be unresolved. Analytical ultracentrifugation methods like sedimentation velocity and equilibrium are presented as alternatives that are sensitive to all aggregate types and sizes. Sedimentation velocity provides high resolution separation while equilibrium can determine equilibrium constants and stoichiometry of reversible associations. On-line light scattering with SEC is also discussed.
This document discusses various aspects of asymmetric synthesis, including stereochemical aspects, acyclic and cyclic stereoselection, and enantioselective synthesis. It defines terms like racemate, enantiopure, and enantiomer. It describes stereospecific and stereoselective reactions, and rules like Cram's rule and Prelog's rule that help explain stereoselection. It discusses strategies for stereoselective synthesis including additions to carbonyls and aldol reactions. It also covers topics like diastereoselective oxidations, catalytic hydrogenation, and enantioselective reductions using chiral reagents like (S)-PBMgCl and (R,R)-DIOP.
Constitutional isomers have the same molecular formula but different connectivity of atoms. Stereoisomers have the same molecular formula and connectivity but different spatial arrangements. There are two types of stereoisomers: enantiomers, which are nonsuperposable mirror images, and diastereomers, which are not mirror images. Chiral molecules are nonsuperposable on their mirror images and exist as enantiomer pairs. The R/S system assigns configurations based on atomic number priorities around stereocenters. Enantiomers have identical physical properties but opposite specific rotations. A racemic mixture contains equal amounts of both enantiomers and has no net rotation.
This document discusses tracer techniques and radioisotopes used in biogenetic studies of plants. It provides details on:
- Tracer techniques involve using radioactive isotopes as markers incorporated into plant metabolite precursors to study biosynthetic pathways.
- Radioisotopes are unstable atoms that decay through emission of particles like alpha, beta, or gamma radiation. Different isotopes have varying half-lives and penetration powers.
- Techniques like precursor-product sequence, double labeling, competitive feeding, and sequential analysis use radioisotopes to study the order and pathways of compound formation in plants.
This document provides information about stereochemistry and optical isomers. It defines different types of isomers such as structural isomers, stereoisomers, enantiomers, and diastereomers. It discusses how compounds can be optically active and how a polarimeter is used to measure optical activity. The R/S system and Cahn-Ingold-Prelog rules for assigning configurations at chiral centers are also explained. The document outlines how reactions involving chiral compounds can result in retention, inversion, or a mixture of configurations depending on whether bonds to the chiral center are broken in the reaction.
1) The document discusses stereochemistry and isomers. It defines key terms like stereoisomers, enantiomers, chiral centers, and optical activity.
2) Enantiomers are nonsuperimposable mirror images that are chiral and optically active, rotating plane-polarized light in opposite directions.
3) The R/S system is used to assign configurations to chiral molecules and stereocenters according to Cahn-Ingold-Prelog priorities.
The document provides information about photosynthesis through a series of questions and answers. It begins by asking the reader to consider a question before revealing the correct answer. It then discusses key topics like the light and dark reactions of photosynthesis, including that the light reactions harness light energy to produce ATP and NADPH, while the dark reactions use these products to fix carbon dioxide and produce glucose.
This document outlines lessons for a 3 week organic chemistry topic. It covers fundamentals of organic chemistry, stereoisomerism including cis/trans, E/Z and optical isomers. It also covers organic reaction types like substitution, addition and oxidation/reduction. Specific lessons cover nucleophilic substitution mechanisms SN1 and SN2, addition reactions to alkenes and benzene, and separating optical isomers. Activities include naming organic compounds, drawing 3D isomer structures, and working through reaction mechanisms and practice questions.
How to use data to design and optimize reaction? A quick introduction to work...Ichigaku Takigawa
(Journal Club) ICReDD Seminar, Apr 27 2020
Institute for Chemical Reaction Design and Discovery (ICReDD)
Hokkaido University
Sapporo, JAPAN
https://www.icredd.hokudai.ac.jp
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
The use of Nauplii and metanauplii artemia in aquaculture (brine shrimp).pptxMAGOTI ERNEST
Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
Unlocking the mysteries of reproduction: Exploring fecundity and gonadosomati...AbdullaAlAsif1
The pygmy halfbeak Dermogenys colletei, is known for its viviparous nature, this presents an intriguing case of relatively low fecundity, raising questions about potential compensatory reproductive strategies employed by this species. Our study delves into the examination of fecundity and the Gonadosomatic Index (GSI) in the Pygmy Halfbeak, D. colletei (Meisner, 2001), an intriguing viviparous fish indigenous to Sarawak, Borneo. We hypothesize that the Pygmy halfbeak, D. colletei, may exhibit unique reproductive adaptations to offset its low fecundity, thus enhancing its survival and fitness. To address this, we conducted a comprehensive study utilizing 28 mature female specimens of D. colletei, carefully measuring fecundity and GSI to shed light on the reproductive adaptations of this species. Our findings reveal that D. colletei indeed exhibits low fecundity, with a mean of 16.76 ± 2.01, and a mean GSI of 12.83 ± 1.27, providing crucial insights into the reproductive mechanisms at play in this species. These results underscore the existence of unique reproductive strategies in D. colletei, enabling its adaptation and persistence in Borneo's diverse aquatic ecosystems, and call for further ecological research to elucidate these mechanisms. This study lends to a better understanding of viviparous fish in Borneo and contributes to the broader field of aquatic ecology, enhancing our knowledge of species adaptations to unique ecological challenges.
2. Part-I: ChiralityPart-I: Chirality
(History, chiral technologies e.g. asymmetric synthesis,(History, chiral technologies e.g. asymmetric synthesis,
absolute configuration, enantiomeric excess)absolute configuration, enantiomeric excess)
Part-II: Origin of lifePart-II: Origin of life
(Origin of homochirality, physical and chemical models)(Origin of homochirality, physical and chemical models)
4. The term Chirality was first used by Lord Kelvin in 1884
Chirality Ξ Handedness
Ξ Non-superimposable mirror image
Objects which are chiral have a sense of handednessObjects which are chiral have a sense of handedness
6. Refers to molecules that interact with plane polarised lightRefers to molecules that interact with plane polarised light
Optical ActivityOptical Activity
7. Louis Pasteur Separated these &Louis Pasteur Separated these &
Gave them to BIOT to measureGave them to BIOT to measure
Pasteur’s DiscoveryPasteur’s Discovery
10. Enantiomers:
Identical physical and chemical properties in an achiral environment
Diastereomers:
Different physical and chemical properties
Different physical properies crystalinity, solubility & polarity allows them to be separated
11. Absolute Configuration (R/S)Absolute Configuration (R/S)
(CAHN-INGOLD-PRELOG CONVENTION)
R/S Nomenclature not synonymous with D/L nomenclatureR/S Nomenclature not synonymous with D/L nomenclature
12. Synthesis of Chiral MoleculesSynthesis of Chiral Molecules
Synthesizing a single enantiomer selectively
Normal reactions produce both enantiomers (50:50), so needs separation or resolution
ResolutionResolution
AsymmetricAsymmetric
SynthesisSynthesis
SingleSingle
EnantiomerEnantiomer
NormalNormal
SynthesisSynthesis
RacemicRacemic
MixtureMixture
13. Enzymatic resolutionEnzymatic resolution
Enzymes are very useful for the resolution of certain compounds • Frequently they
display very high selectivity • There can be limitations due to solubility, normally
only one enantiomer exists and can be too substrate specific
14. Stereoselective(Asymmetric) SynthesisStereoselective(Asymmetric) Synthesis
Diastereoselective or enantioselective synthesis or the synthesis of chiral molecules
Use enantiomerically pure starting material and stereospecific reactions
Good - if a cheap, readily available source of chirality exists
Problems - often results in long, tortuous syntheses .......................
suitable material not always available
A. Chiral PoolA. Chiral Pool
15. Chiral auxiliary - allows enantioselective synthesis via diastereoselective reaction
Add chiral unit to substrate to control stereoselective reaction
Can act as a built in resolving agent (if reaction not diastereoselective)
Problems - need point of attachment, adds additional steps, cleavage conditions must
not damage product!
B. Chiral AuxillaryB. Chiral Auxillary
16. Chiral reagent - stereochemistry initially resides on the reagent
Advantages - No coupling / cleavage steps required
Often override substrate control
Can be far milder than chiral auxiliaries
Disadvantages - Need a stoichiometric quantity (not atom economic)
.................Frequently expensive ..........Problematic work-ups
C. Chiral ReagentC. Chiral Reagent
17. Chiral catalysis - ideally a reagent that accelerates a reaction (without being
destroyed) in a chiral environment thus permitting one chiral molecule to generate
millions of new chiral molecules.
D. Chiral CatalystD. Chiral Catalyst
18. ((Enantiomeric Excess (ee)Enantiomeric Excess (ee)))
Measuring ChiralityMeasuring Chirality
• Optical purity:Optical purity: a way of describing the composition of
a mixture of enantiomers
• Enantiomeric excess:Enantiomeric excess: the difference between the
percentage of two enantiomers in a mixture
optical purity is numerically equal to enantiomeric
excess, but is experimentally determined
x 100
[α]sample
Percent optical purity =
[α]pure enantiomer
x 100
[R] + [S]
[R] - [S]
Enantiomeric excess (ee) = = %R - %S
23. 3. Chiral Derivatizing agents3. Chiral Derivatizing agents
A good chiral derivatising agent should:
• Be enantiomerically pure (or it is pointless)
• Coupling reaction of both enantiomers must reach 100% (if you are measuring ee)
• Coupling conditions should not racemise stereogenic centre
• Enantiomers must contain point of attachment
• Above list probably influenced depending whether you are measuring %ee or
preparatively separating enantiomers
24. Derivatizing Agents: Mosher’s acid
Popular derivatising agent for alcohols and amines :
α-methoxy-α- trifluoromethylphenylacetic acid or Mosher’s acid
Difference in nmr signals between diastereoisomers (above):
1
H nmr Δδ = 0.08 (Me) 19
F nmr Δδ = 0.17 (CF3)
No α-hydrogen so configurationally stable
Diastereoisomers can frequently be separated
30. "Deducing the mechanism of the origin of life on earth has always
remained a fascinating but unsolved puzzle. Some have even
considered it too difficult for scientific study, because the direct
evidence is long gone, and we can only work by plausible
inference."
-R.H. Crabtree, Science, 1997, 276, 222
"Biogenesis, as a problem of science, is lastly going to be a problem
of synthesis. The origin of life cannot be 'discovered', it has to be
re-invented."
-A. Eschenmoser, Tetrahedron, 2007, 63, 12821-12844.
31. Living or not?Living or not?
Seven life processes:- from bacteria to plants to animals
1 Nutrition/feeding.
2 Growth.
3 Movement.
4 Respiration/breathing.
5 Reproduction.
6 Sensitivity.
7 Excretion
32. Primordial Soup TheoryPrimordial Soup Theory
(Soviet biologist Alexander Oparin, 1924)
1. Early Earth had a chemically reducing atmosphere.
2. This atmosphere, exposed to energy in various forms, produced
simple organic compounds ("monomers").
3. These compounds accumulated in a "soup", which may have been
concentrated at various locations (shorelines, oceanic vents etc.).
4. By further transformation, more complex organic polymers and
ultimately life – developed in the soup.
33. Miller-Urey ExperimentMiller-Urey Experiment
Miller, Stanley L. Science, 1953, 117 (3046): 528–9
"Production of Amino Acids Under Possible Primitive Earth Conditions""Production of Amino Acids Under Possible Primitive Earth Conditions"
34. Homochirality is a term to describe a group of moleculesHomochirality is a term to describe a group of molecules
that possess the same sense of chiralitythat possess the same sense of chirality
Origin of LifeOrigin of Life Origin of HomochiralityOrigin of Homochirality
Homochirality is precondition of lifeHomochirality is precondition of life
??? How did life choose its handedness?????? How did life choose its handedness???
??? How did enantiopurity arise from a racemic prebiotic world?????? How did enantiopurity arise from a racemic prebiotic world???
35. Conclusion from Part-IConclusion from Part-I
Chirality is created in presence of a chiral directing for
(Chiral pool, chiral auxillary, chiral catalyst,
chiral reagent, & circularly polarised light)
Absolute asymmetric synthesis
How the first chiral compound synthesized???
36. The Hypothesis for Homochirality
3. Chiral Transmission
1. Mirror Symmetry Breaking
Racemic
0% ee
2. Chiral Amplification
Homochiral
100% ee
38. 1.Franck’s Autocatalytic1.Franck’s Autocatalytic
ModelModel
Biochim. Biophys. Acta, 1953, 11, 459-463
Autocatalysis & mutual antagonism
“A laboratory demonstration may not be impossible”
Am
plification
M
echanism
Sigmoid variation of product
Concentration in autocatalytic reaction
45. Blackmonds Model for Soai ReactionBlackmonds Model for Soai Reaction
J. Am. Chem. Soc. 2001, 123, 10103-10104
Am
plification
M
echanism
46. 2. Chiral Amnesia Model2. Chiral Amnesia Model
(Solid phase homochirality)(Solid phase homochirality)
C. Videma, Astrobiology, 2007, 7, 312-319
Am
plification
M
echanism
47. Chiral Amnesia ModelChiral Amnesia Model
(Organic Solid Phase Homochirality)(Organic Solid Phase Homochirality)Am
plification
M
echanism
48. Gradient heating to 1600
Isothermal @ 900
Chiral Amnesia ModelChiral Amnesia Model
(Organic Solid Phase Homochirality)(Organic Solid Phase Homochirality)Am
plification
M
echanism
49. 3. Eutectic Model3. Eutectic Model
(Solution phase homochirality)(Solution phase homochirality)
Eutectic enantiomeric excess (ee eut
)
Klussmann et. Al., J. Am, Chem, Soc, 2007, 123, 7657.
Am
plification
M
echanism
50. Blackmond et.al. Chem. Commun., 2007, 3990
Eutectic ModelEutectic Model
(Solution phase homochirality)(Solution phase homochirality)Am
plification
M
echanism
51. ConclusionConclusion
1. Chemical models provide a plausible pathway for the evolution of
homochirality in nature
2. These investigations will be helpful in the new field of “Systems
Chemistry” which will uncover the chemical roots of biological
organization ultimately enable the engineering of novel biological
systems & functions
3. Building systems that can self-recognize & self assemble, process
information, transport material and energy impact future
technology in areas of material science, synthetic biology
and pharmaceuticals