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2,3 dichloropentane

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2,3 dichloropentane

  1. 1. Made by:- Sofia Mubashir Topic:- 2,3-dichloropentane
  2. 2. “2,3-dichloropentane” • Stereoisomerism • Optical Isomerism • Optical Activity • Chiral Center • Enantiomers • Fischer Projection • R/S Rotation • Racemization • Method Of Racemization • Resolution
  3. 3. Stereoisomerism Stereoisomerism is defined as “ isomerism in compounds having equal number of same types of bonds with identical connectivity , but differing in the spatial arrangement of atoms.” Stereo isomers are divided into two classes  Configurational Stereoisomerism  Conformational stereoisomerism
  4. 4. non-polarized polarized Optical activity:- When a substance rotates the plane of plane polarized light. Plane polarized light:- Light that has been passed through nicol prism or other polarizing medium so that all of the vibration are in the same plane.
  5. 5. polarimeter – an instrument used to measure optical activity. light source sample tube polarizer analyzer
  6. 6. Diastereomers: Stereoisomers • There are many molecules with two or more stereogenic centers that have diastereomers. • Every diastereomer can have a mirror image, which constitutes two stereoisomers. • A molecule with two stereogenic centers will have up to two diastereomers and each will have a mirror image. This means there is a maximum total of four stereoisomers for a molecule with two stereogenic centers. • This observation can be extended to all molecules that have stereogenic centers. For a given number of stereogenic centers (say n) there will be a maximum of 2n stereo isomers. • A molecule with two stereogenic centers has 22 or 4 stereoisomers. • A molecule with 4 stereogenic centers will have a maximum of 24 or 16 stereoisomers. • If a molecule has 9 stereogenic centers, the maximum number of stereoisomers will be 29 or 512 stereoisomers. • A molecule with 28 stereogenic centers; 228 means 2.684 x 108 stereoisomers (that's more than 268 million stereoisomers) for one constitutional isomer of a single empirical formula.
  7. 7. Diastereomers Enantiomers: Mirror-image stereoisomers. Diastereomers: Stereoisomers which are not enantiomers.
  8. 8. I is a stereoisomer of III & IV. II is a stereoisomer of III & IV. I is not a mirror image of III or IV. II is not a mirror image of III or IV. Therefore, I is a diastereomer of III & IV. II is a diastereomer of III & IV. Diastereomers often have similar, but not identical, chemical properties. They have different physical properties, and can be separated from one another by ordinary physical means.
  9. 9. Fisher Projections + A method of representing stereogenic centers without using wedged or dashed bonds. Horizontal bonds come from the stereogenic center toward you. Vertical bonds go from the stereogenic center away from you. e.g.
  10. 10. R And S Configurations From Fischer Projection: To determine the R,S configuration of each. • interchange pairs of groups around the stereogenic center of one until both projections are identical. • Since each exchange inverts the configuration anodd number of exchanges means the configurationswere opposite; an even number means they are the same.
  11. 11. Racemization: “Racemization is the process by which 50 % of an optically active compound ( dextro or levo) may be converted to its enantiomer.”
  12. 12. Method Of Racemization Consider an optically active halide. The process of racemization would involve the removal of halide ion from the sp3 carbon. This is possible in a solvent which can stabilize the carbocation.
  13. 13. Resolution Of Racemic Mixture: “The separation of enantiomers from racemic mixture is called resolution of racemic mixture. Following special methods have been used for separation of enantiomers from racemic mixture: 1. Mechanical method 2. Biological method 3. Chemical method 4. Chromatographic method

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