Orgo 5.4-5.6

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Orgo 5.4-5.6
2013-10-14 09:47:00
CHM 201

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  1. Differences in enantiomers become apparent when?
    in their interactions with other chiral molecules
  2. __ is a common method used to distinguish between enantiomers, based on their ability to rotate hte plane of polarized light in opposite directions.
  3. Most of what we see is __, vibrating randomly in all directions. __ is composed of waves that vibrate in only one plane. Although there are other types of __, the term usualyl refers to __.
    • unpolarized light
    • plane-polarized light
    • "polarized light" 
    • plane-polarized light
  4. When __ light passes through a __ ilter, the randomly vibrating light waves are filtered so that most of the light passing through is __.
    • unpolarized
    • polarizing 
    • vibrating in one direction
  5. The direction of vibration is called the __ of the filter. Polarizing filters may be made from carefully cut __ or from specially treated __.
    • axis
    • calcite crystals
    • plastic sheetes
  6. When light passes first through one __ and then through another, the amount of light emerging depends on what?
    • polarizing filter
    • the relationship between the axes of the two filters
  7. If the axes of the two filters are lined up (parallel), then what?
    nearly all the light that passes through the first filter also passes through the second.
  8. IF the axes of the two filters are perpendicular (crossed poles), what?
    all the polarized light that emerges from the first filter is stopped by the second
  9. At intermediate angles of rotation, what?
    intermediate amounts of light pass
  10. When polarized light passes through a solution containing a chiral compound, the chiral compound causes __. Rotation of hte plane of polarized light is called __, and substances that rotate the plane of polarized liht are said to be __.
    • the plane of vibration to rotate
    • optical activity
    • optically active
  11. Two enantiomers have iddentical __, except for _. Ennantiometric compounds rotate the __ by exactly the same amount but in opposite directions.
    • physical properties
    • the direction they roate the plane of polarized light. 
    • plane of polarized light
  12. True or False:
    We can predict which direction a particular enantiomer will rotate the plane of polarized light
    • False:
    • we can not
  13. A __ measures the rotation of polarized lgiht. IT has a tubular cell filled with a solution of the optically active material and a system for passing polarized light through the solution and measuring the roation as the lgiht emerges.
  14. The wavelength of light most commonly used for polarimetry is what?
    a yellow emission line in the spectrum of sodium, called the sodium D line.
  15. __ light from the source passes through a polarizing filter, then through the sample cell containing a solution of hte optically active compound. On leaving the sample cell, the polarized light encounters what? This __ is __, with a scale allowing the operator to read the angle between the axis of the second (__) filter and the axis of the first (__) filter.
    • monochromatic (one-color)
    • filter
    • movable
    • analyzing
    • polarizing
  16. The operator rotates the __ until the maximum amount of light is transmitted, then reads the observed rotation from the protractor. The observed rotation is symbolized by what?
    • analyzing filter
    • alpha
  17. Compounds that rotate the plane of polarized light toward the right (clockwise) are called __.
    Compounds that rotate the plane toward the left are called __. These terms are sometiems abbreviated by __. Using IIUPAC notation, the direction of roation is specified by the __ sign.
    • dextrorotatory
    • levorotatory
    • d or l
    • + or -
  18. Dextrotatory rotations are __ or __.
    Levorotatory rotations are __ or __.
    • + or d
    • - or l
  19. The __ of polarized light by a chiral compound is a characteristic physical property of that compound. The rotation observed in a polarimeter depends on the what?
    • angular rotation
    • concentration of the sample solution and the length of the cell,as wella s the optical activity of the compound
  20. To use the rotation of polarized light as a characteristic property of a compound, we must what?
    standardize the conditions for measurement.
  21. We define a compound's __ as the rotation found using a 10-cm sample cell and a concentration of 1 g/ mL. Other cell lengths and concentrations may be used, as long as what?
    • specific rotation
    • observed rotation is divided by the path length of the cell and the concentration
  22. A rotation depends on what?
    the wavelength of lgiht used and also on the temperature
  23. Any __ can distinguish between enantiomers, and a polarimeter is only oe example of a __.
    chiral probe x2
  24. Enzymes in living systems are __, and they are capable of distinguinshing between __. Usulaly, only one __ of a pair fits properly into the chiral active site of an enzyme.
    • chiral
    • enantiomers x2
  25. In general, just one of the enantionmers produces the characteristic effect; the other does what/
    either produces no effect or has a different effect
  26. In general, enantiomers do not what?
    interact identically with other chiral molecules, whether or not they are of biological origin
  27. A soluton of equal amounts of two enantiomers,so that the mixture is optically inactive, is called a __, which can also be called a __, __, or __.
    • racemic mixture
    • racemate
    • (±) pair
    • (d,l) pair
  28. True or False:
    Many reactions led to racemic products, especialy when an achiral molecule is converted to a chiral molecule.
  29. A reaction that uses optically __ and __ cannot produce a product that is optically active. Any __ must be formed as a __.
    • inactive reactants
    • catalysts
    • chiral product
    • racemic mixture