Group 6 Organic Chemistry of isomerism ppt

This document describes different forms of isomerism, isomerism,diastereoisomeri

1. Group 6 Organic Chem 2

2. Members Name Reg. No. KATUSIME JULIAN VU-BPC-2307-0167-DAY BALIKUDEMBE JOSEPH VU-BPC-2307-0912-DAY ANGENGEUN EUNICE BLESSING VU-BPC-2307-0861-DAY

3. Key words Isomers: compounds with same chemical & molecular formula but different structure Stereoisomers: Compounds with same chemical formula but different spatial arrangement. Diastereomers : Are stereoisomers  that are non identical, do not have mirror images, and hence are non-superimposable on each other. i.e. Differ in at least 1 chiral carbon but not all. E.g . Cis-2-butene & trans-2-butane, C 6 H 12 O 6 isomers (D- glucose, D-galactose, D-Mannose & D-fructose) Epimers : Are Diastereomers that differ in configuration at only one asymmetric carbon ( stereocenter ). They have the same molecular formula and connectivity, but the orientation of one substituent group is different

4. Racemisation : is defined as  “a process by which an optically active substance either dextro or levorotatory, is directly converted into a racemate ” . Racemate : A racemic mixture is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule or salt.

5. Steriochemistry of Epimers C- epimers ( differ in the configuration of a carbon atom, ) Anomers are a specific type of epimers where the configuration differs at the anomeric carbon , Other C- Epimers refer to epimeric pairs where the stereochemistry differs at a carbon atom that is not the anomeric carbon . N- Epimers are stereoisomers that differ in the configuration of a nitrogen atom S- Epimers are stereoisomers that differ in the configuration at a sulfur atom P- Epimers refer to epimers that differ in the configuration of a phosphorus atom

6. Examples D-ribose and D-arabinose are C-2 epimers D- idose and D- talose are C-3 epimers .

7. Examples

8. Synthesis of epimers : Nucleophilic substitution reactions SN 2 reaction: SN 1 reaction:

9. Synthesis of epimers : Elimination-Addition Reactions E2 reactions

10. Synthesis of epimers : Re-dox Reactions Oxidation of alcahols Other methods Cycloaddition ( Diels-Alder ) Reactions Rearrangement Reactions

11. Functional groups in epimers Hydroxyl (OH ) group carbonyl (C=O) group

12. Hydroxyl Group Physical properties OH group Hydrogen bonding between hydrogen & oxygen Electronegativity (ability to attract shared electrons in a chemical bond) dipole moment ( unequal distribution of electron density within the O-H bond, with the oxygen atom having a partial negative charge and the hydrogen atom a partial positive charge). Chemical reactions of OH group Nucleophilic substitution Elimination Oxidation reactions

13. carbonyl (C=O) group Physical properties The carbon-oxygen double bond is highly polar dipole moment (unequal distribution of electron density within the C-O double bond , with the oxygen atom having a partial negative charge and the carbon atom a partial positive charge). Chemical reactions Nucleophilic addition Redox reactions

14. Application of epimers Quality control e.g. Chiral chromatography is an analytical technique in epimer research for identifying, characterizing, and quantifying epimeric forms of pharmaceuticals to ensure consistent drug quality and efficacy . Drug development Stereoisomer Screening is a process in drug development where researchers systematically evaluate and compare the biological activities of different spatial arrangements of atoms within a drug molecule to identify the most promising stereoisomer for further optimization.

15. Applications continued Improved drug delivery Epimer -based prodrugs are pharmaceutical compounds designed to leverage the different biological properties of epimeric forms to improve drug delivery and enhance therapeutic efficacy . Study of metabolic pathways (e.g. Epimer -dependent enzyme kinetics) Diagnostics epimers can be used to test for carbohydrates like starch & glycogen, which are important biomarkers for digestive disorders . Epimers can also be used to differentiate between various types of lipids , such as cholesterol and triglycerides which are important biomarkers for heart disease and other metabolic disorders.

16. Applications continued Post marketing surveillance of chiral drugs: involves closely monitoring the safety and efficacy of drug products containing chiral molecules after they have been approved and are in widespread clinical use, to detect any differences between the individual drugs.

17. Stereochemistry of Quasi- racemates Quasi- racemate : is defined as a 1:1 mixture of quasi-enantiomers that may form a compound, aeutectic mixture, or a solid solution and shows typical compound behaviour in the phase diagram. Example. An e quimolar mixture of (+)- Chlorosuccinic acid and (+)- Bromosuccinic acid form aquasi-racemate and shows eutectic behaviour similar to that of a conglomerate.

18. Quasi- racemates are a type of stereoisomeric mixture where the components are not strictly enantiomers, but have a similar degree of stereochemical nonequivalence . Examples Enantiomeric quasi- racemates are mixtures of two or more enantiomers that exhibit properties similar to a true racemic mixture, despite not having a 1:1 ratio of the enantiomers. These quasi- racemates can display physical and chemical properties that are intermediate between the pure enantiomers, making them useful in various applications where a racemic mixture is preferred. Non-Enantiomeric Quasi- Racemates refer to a type of crystalline solid that contains both enantiomers (mirror-image molecules) and non-enantiomeric components in the same crystal lattice. This unique arrangement results in properties that differ from a true racemic mixture, where the enantiomers are present in equal amounts. The inclusion of non-enantiomeric species creates an asymmetric environment that can lead to distinct physical and chemical characteristics

19. Applications of quasi racemates Bioactivity evaluation in pharmaceutics (enantiomeric purity control) During natural product reaserch for Structure elucidation: is the process of determining the molecular structure of a chemical compound, typically through the use of analytical techniques such as spectroscopy and crystallography . Development of Chiral Drug Intermediates: these are important chemical precursors used in the pharmaceutical industry to produce enantiomerically pure drug molecules, where the specific stereochemistry is crucial for the desired therapeutic effect.

20. Asymmetric molecules Asymmetric molecules in racemization refers to the process where a chiral molecule (one that is non-superimposable on its mirror image) can convert into a racemic mixture, containing equal amounts of the two mirror-image forms. This occurs when the molecule undergoes a chemical reaction that breaks the bonds holding the asymmetric structure, allowing the molecule to reform in either of the two possible chiral configurations. Eg . Basing on chirality (enantiomers

21. compounds with dissimilar chiral centers A compound with dissimilar chiral centers refers to a molecule that contains two or more carbon atoms with tetrahedral geometry, each bearing four different substituents, resulting in the formation of non-superimposable mirror images (enantiomers). The presence of these distinct chiral centers gives rise to unique stereochemical configurations within the compound, leading to differences in the spatial arrangement of the atoms and potential variations in chemical and biological properties.

22. Examples of compounds with dissimilar chiral centers Levodopa/Carbidopa  used in parkinsonism Pseudoephedrine and ephedrine are enantiomers, mirror-image molecules with different biological activities. Pseudoephedrine is a decongestant, while ephedrine has additional stimulant effects. Dextromethorphan and levomethorphan   Ibuprofen and naproxen Tamoxifen and Toremifene

23. dissimilar chiral centers

24. Synthesis of compound with dissimilar chiral centers The Chiral Pool Approach to asymmetric synthesis involves using readily available chiral starting materials, such as naturally occurring amino acids or carbohydrates, as the source of chirality, rather than introducing a chiral auxiliary or relying on enzymatic resolution .

25. Synthesis The Chiral Auxiliary Approach to asymmetric synthesis utilizes a temporary chiral element attached to the substrate, which is later removed, to control the stereochemistry of the final product .

26. Applications compounds with dissimilar chiral centers Toxicology studies e.g. Stereoselective toxicity studies of drugs drug interaction studies: Enantioselective inhibition of metabolic enzymes refers to the ability of one stereoisomer (enantiomer) of a compound to selectively inhibit the activity of certain enzymes involved in drug metabolism, while the other enantiomer may have a different or no effect . Signal transduction e.g. Stereospecific activation of signaling pathways occurs when a drug's different stereoisomers selectively activate distinct signal transduction cascades within the target cell, leading to divergent biological effects.