Chapter 5 Notecards

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  1. Absolute Configuration
    the actual arrangement of groups in a molecule. This can be determined by x-ray analysis will by relating the configuration of a molecule, using reactions of known stereochemistry, to another molecule
  2. Achiral Molecule
    a molecule that is superposable on its mirror image. These molecules lacking handedness and are incapable of existing as a pair of enantiomers
  3. Atropisomers
    conformational isomers that are stable, isolable compounds
  4. Chiral Molecule
    a molecule that is not superposable on its mirror image. these molecules have handedness and are capable of existing as a pair of enantiomers
  5. Chirality
    the property of having handedness
  6. Chirality Center
    an atom bearing groups of such nature that an interchange of any two groups will produce a stereoisomer
  7. Configurations
    a particular arrangement of atoms (groups) in space that is characteristic of a given stereoisomer
  8. Constitutional Isomers
    compounds that have the same molecular formula but that differ in their connectivity (i.e., molecules that have the same molecular formula but have their atoms connected in different ways).
  9. Dextrorotatory
    a compound that rotates plane-polarized light clockwise
  10. Diastereomers
    stereoisomers that are not mirror images of each other
  11. Diastereoselective Reaction
  12. Enantiomeric Excess
    a percentage calculated for a mixture of enantiomers by dividing the moles of one enantiomer minus the moles of the other enantiomer by the moles of both enantiomers and multiplying by 100. This equals the percentage of optical purity.
  13. Enantiomerically Pure
  14. Enantiomers
    stereoisomers that are mirror images of each other
  15. Enantioselective Reaction
  16. Fischer Projections
    a two-dimensional formula for representing the configuration of acheiral molecule. By convention, these formulas are ring with the main carbon chain extending from top to bottom or groups. Vertical lines represent bonds that projects behind the plane page (with like in it). Horizontal lines represent bonds that project out of the plane of the page.
  17. Isomers
    different molecules that have the same molecular formula
  18. Kinetic Resolution
    a process in which the rate of a reaction with one enantiomer is different is different than with the other, into a preponderance of one product stereoisomer. This process is said to be “stereoselective” and that it leads to the preferential formation of one stereoisomer over other stereoisomers that could possibly be formed.
  19. Levorotatory
    a compound that rotates plane-polarized light in a counterclockwise direction
  20. Meso Compound
    an optically inactive compound whose molecules are achiral even though they contain tetrahedral atoms with four different attached groups
  21. Optical Purity
    a percentage calculated for a mixture of enantiomers by dividing the observed specific rotation for the mixture by the specific rotation of the pure enantiomer and multiplying by 100. The optical purity equals the enantiomeric purity or enantiomeric excess.
  22. Optically Active Compounds
    a compound that rotates the plane of polarization of plane-polarized light
  23. Plane Of Symmetry
    an imaginary plane that bisects a molecule in a way such that the two halves of a molecule are mirror images of each other. Any molecule with a plane of symmetry will be achiral.
  24. Plane-Polarized Light
    light in which the oscillations of the electrical field occur only in one plane
  25. Polarimeter
    a device used for measuring optical activity
  26. R,S-System
    a method for designating the configuration of tetrahedral chirality centers
  27. Racemic Form
    an equimolar mixture of enantiomers. A racemic form is optically inactive.
  28. Relative Configuration
    the relationship between the configurations of two chiral molecules. Molecules are said to have this configuration when similar or identical groups each occupy the same position in space. The configuration of molecules can be related to each other through reactions of known stereochemistry, for example, through reactions that cause no bonds to a stereogenic center to be broken.
  29. Resolutions
    the process by which the enantiomers of a racemic form are separated
  30. Specific Rotation
    a physical constant calculated from the observed rotation of a compound using the following equation: where is the observed rotation using the D line of a sodium lamp, the concentration of the solution density of the neat liquid grams per milliliter, and is the length of the tube in decimeters
  31. Stereochemistry
    chemical studies that take into account spatial aspects of molecules
  32. Stereogenic Carbon
    a single tetrahedral carbon with four different groups attached to it. Also called an asymmetric carbon, a stereo center, or a chirality center. The last usages is preferred.
  33. Stereogenic Center
    when the exchange of two groups bonded to the same atom produces stereoisomers, the atom is said to be a stereogenic atom or this
  34. Stereoisomers
    compounds with the same molecular formula that differ only in the arrangement of their atoms in space. These compounds have the same connectivity and, therefore, are not constitutional isomers. These compounds are classified further as being either enantiomers or diastereomers
  35. Stereoselective Reactions
    reactions where chirality centers are altered, these reactions produce a ponderous of one stereoisomer. Furthermore, these reactions can be either enatioselective, in which case the reaction produces a preponderance of one enantiomer, or diastereoselective, in which case the reaction produces a preponderance of one diastereomer.
  36. Superposable
    two objects are this is, when one object is placed on top of the other, all parts of each coincide. This is different than to be superimposable. Any two objects can be superimposed simply by putting one object type of the other, whether or not all parts coincide. The condition of this must be met for two things to be identical.

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Chapter 5 Notecards
2016-07-17 01:35:18
Chapter 5 Notecards
Chapter 5 Stereochemistry
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