CHEM2310 ppt Ch 06 by TpVChV

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									                         Stereochemistry
                 Introduction: Putting it all together


                       Why is it all important?
                        • functional groups
                              • shapes

                        Functional groups:
            Groups things by how they ______________

                             Shapes:
 Enzymes are dependent on shape and are the body’s ___________.
Receptors are dependent on shape and send out chemical messengers.

                            CHEM2310 Ch 6                      1
        Stereochemistry
Introduction: Putting it all together




           CHEM2310 Ch 6                2
        Stereochemistry
Introduction: Putting it all together




           CHEM2310 Ch 6                3
        Stereochemistry
Introduction: Putting it all together




           CHEM2310 Ch 6                4
        Stereochemistry
Introduction: Putting it all together
       Competitive inhibition:




           CHEM2310 Ch 6                5
       Review: Stereochemistry and the sp3 hybridized C

                  Enantiomers and Chirality
             Light travels in photons (light packets),
                 which vibrate in a plane (flat)




Ordinary light contains many photons, which vibrate in all planes
A polarizer only allow light traveling in one plane to pass through




                          Polarized light

                           CHEM2310 Ch 6                          6
Review: Stereochemistry and the sp3 hybridized C

          Enantiomers and Chirality

                                Polarized light



    Chiral sample                   non-Chiral sample




                    CHEM2310 Ch 6                       7
    Review: Stereochemistry and the sp3 hybridized C


 One enantimer sample




                              Other enantimer sample




Racemic Mixture (50/50)


                        CHEM2310 Ch 6                  8
      Review: Stereochemistry and the sp3 hybridized C

   Physiological properties are different between enantiomers
                  for which of the following?
enzyme structure    enzyme function         enzyme activity
medications         iron in the blood       taste
reactivity          neurons                 poisons
carbohydrates       proteins                intensive care units
surgery       metabolism            drug testing


          Do you see a problem that might easily arise,
                  due to the above answers?


                          CHEM2310 Ch 6                         9
                Specific Rotation


The following are the 2 enantiomers of butan-2-ol:




 (S)-(+)-butan-2-ol:             (R)-(-)-butan-2-ol:
      25                                25
   [α]D =   +13.52°                   [α]D = -13.52°




                      CHEM2310 Ch 6                    10
                        Specific Rotation
           The observed rotation (α) is dependent on:
                      • the specific rotation,
                • the length of the tube (in dms),
                        • the concentration
                         • the temperature
             • the light source (D line of sodium)


                         α = [α]25 x Length x Concentration
                                D


                                 note: 1 dm = 10 cm
(S)-(+)-butan-2-ol:
    25
                      note: the sign (+ or -) MUST be included.
 [α] D =   +13.52°


                         CHEM2310 Ch 6                        11
                      Specific Rotation


What is the observed rotation (α) for a 2.00 g (S)-(+)-butan-2-ol
 sample dissolved in 100.0 mL of solvent and a sample tube
                      length of 10.0 cms?



                          α = [α]25 x Length x Concentration
                                 D




(S)-(+)-butan-2-ol:
     25
  [α] D =   +13.52°


                         CHEM2310 Ch 6                         12
                      Specific Rotation
  A solution prepared by dissolving 400.0 mg of testosterone, a
   male sex hormone, in 10.0 mL of of ethanol is placed in a
sample tube 1.00 dm in length. The observed rotation (at 25°C),
  using the D line of sodium, is +4.36°. Calculate the specific
                     rotation of testosterone.


                         α = [α]25 x Length x Concentration
                                D




     25
  [α]D =   ?


                        CHEM2310 Ch 6                         13
Specific Rotation Suggested Homework:

Chapter 6 Exercises: 6, 7, 31, 33




                                        CHEM2310 Ch 6   14
                  Specifying Configuration
     The following are the 2 enantiomers of butan-2-ol:




      (S)-(+)-butan-2-ol:             (R)-(-)-butan-2-ol:
           25                                25
        [α]D =   +13.52°                   [α]D = -13.52°


How do we determine which enantiomer is + and which is -?
         Now, we need to know how to determine
          which enantiomer is R and which is S!

                           CHEM2310 Ch 6                    15
             Specifying Configuration
The following are the 2 enantiomers of butan-2-ol:




 (S)-(+)-butan-2-ol:             (R)-(-)-butan-2-ol:
      25                                25
   [α]D =   +13.52°                   [α]D = -13.52°


Step 1: Prioritize the substituents from highest (1)
                    to lowest (4).


                      CHEM2310 Ch 6                    16
       Review: E, Z Designations of Alkenes


          Use the atomic number of each atom to determine priority:
                     1. Look at the atom directly bonded.
         2. If needed, look at all atoms bonded to the atom in step #1.
                  Count each atom doubly if double bonded.
                    Count each atom triply if triple bonded.



Prioritize the following groups from highest to lowest:
                           -Cl
                          -CH3
                       -C(CH3)3
                         -CHO
                        -C CH



                            CHEM2310 Ch 6                                 17
             Specifying Configuration
The following are the 2 enantiomers of butan-2-ol:




 (S)-(+)-butan-2-ol:             (R)-(-)-butan-2-ol:
      25                                25
   [α]D =   +13.52°                   [α]D = -13.52°

Step 1: Prioritize the substituents from highest (1)
                    to lowest (4).



                      CHEM2310 Ch 6                    18
             Specifying Configuration
The following are the 2 enantiomers of butan-2-ol:




 (S)-(+)-butan-2-ol:                   (R)-(-)-butan-2-ol:
      25                                     25
   [α]D =   +13.52°                      [α]D = -13.52°

       Step 1: Prioritize the substituents from highest (1)
                           to lowest (4).

     Step 2: Put the lowest (4) in the back.


                       CHEM2310 Ch 6                          19
             Specifying Configuration
The following are the 2 enantiomers of butan-2-ol:




 (S)-(+)-butan-2-ol:                   (R)-(-)-butan-2-ol:
      25                                     25
   [α]D =   +13.52°                      [α]D = -13.52°

       Step 1: Prioritize the substituents from highest (1)
                           to lowest (4).
             Step 2: Put the lowest (4) in the back.

        Step 3: Determine if 1→2→3 is
     clockwise (+) or counter clockwise (-).
                       CHEM2310 Ch 6                          20
                   Specifying Configuration
Two tricks that can help with determining R and S enantiomers.




1) If you “trade” any 2 substituents, you will get the enantiomer.
       2) If you figure the 4th (lowest) priority in the front,
    you will get the configuration (R or S) of the enantiomer.
                          CHEM2310 Ch 6                         21
                   Specifying Configuration
     Determine if the following are the R or S enantiomer.
              Step 1: Prioritize the substituents from highest (1)
                                  to lowest (4).
                    Step 2: Put the lowest (4) in the back.
                       Step 3: Determine if 1→2→3 is
                    clockwise (+) or counter clockwise (-).




a)                                             b)




                              CHEM2310 Ch 6                          22
             Specifying Configuration
Determine the fullest name of the compound possible.


a)


      lactic acid
     [α]D = -3.33°

                            b) the enantiomer of (a)




                     CHEM2310 Ch 6                     23
             Specifying Configuration




   Draw the structure of:
 a) (R)-3-methylpent-1-ene
b) (S)-3-methylcyclopentene
     c) (S)-ibuprofen


                                        ibuprofen



                    CHEM2310 Ch 6                   24
        Specifying Configuration


 Which of the following are enantiomers?
a) (2R,3R)-2-amino-3-hydroxybutanoic acid
b) (2R,3S)-2-amino-3-hydroxybutanoic acid
c) (2S,3R)-2-amino-3-hydroxybutanoic acid
d) (2S,3S)-2-amino-3-hydroxybutanoic acid




               CHEM2310 Ch 6                25
Specifying Configuration Suggested Homework:

Chapter 6 Exercises: 8 – 10, 27, 28, 30, 36 – 41




                                                   CHEM2310 Ch 6   26
     Enantiomers and Diastereomers


             Stereoisomers:
a) (2R,3R)-2-amino-3-hydroxybutanoic acid
b) (2R,3S)-2-amino-3-hydroxybutanoic acid
c) (2S,3R)-2-amino-3-hydroxybutanoic acid
d) (2S,3S)-2-amino-3-hydroxybutanoic acid


        The others are diastereomers.
(stereoisomers that are NOT mirror images)



               CHEM2310 Ch 6                 27
     Enantiomers and Diastereomers


             Stereoisomers:
a) (2R,3R)-2-amino-3-hydroxybutanoic acid
b) (2R,3S)-2-amino-3-hydroxybutanoic acid
c) (2S,3R)-2-amino-3-hydroxybutanoic acid
d) (2S,3S)-2-amino-3-hydroxybutanoic acid




               CHEM2310 Ch 6                28
               Enantiomers and Diastereomers


      First: verify the configurations (R or S) is correct.




Second: determine if each pair are enantiomers or diastereomers.


                         CHEM2310 Ch 6                        29
Enantiomers and Diastereomers Suggested Homework:

Chapter 6 Exercises: 12 – 14, 42, 43, 44, 46, 47




                                                   CHEM2310 Ch 6   30
                     Meso Compounds

                     2,3-dichlorobutane:
         First: Determine the configurations (R or S).




Second: determine if each pair are enantiomers or diastereomers.


                         CHEM2310 Ch 6                       31
Meso Compounds

2,3-dichlorobutane:




    CHEM2310 Ch 6     32
                            Meso Compounds

          Do each of the following have a meso form?

a)                     b)                      c)
                                                    CH3CH(OH)COOH
                                                      lactic acid


                             ibuprofen
 tartaric acid
                      d) 2,3-dibromopentane
                   e) 2,2,4,4-tetrabromopentane
                 f) 2,4-dibromo-2,4-dichloropentane
                              CHEM2310 Ch 6                         33
                       Meso Compounds

                  Back to 2,3-dichlorobutane:




Determine if each pair are enantiomers, diastereomers, or the same.


                          CHEM2310 Ch 6                        34
Meso Compounds Suggested Homework:

Chapter 6 Exercises: 16, 17, 45, 48, 49




                                          CHEM2310 Ch 6   35
        Molecules with >2 Stereocenters
The following are the 2 enantiomers of butan-2-ol:




 (S)-(+)-butan-2-ol:             (R)-(-)-butan-2-ol:
      25                                25
   [α]D =   +13.52°                   [α]D = -13.52°

    Notice that when there is 1 stereocenter,
     there are 2 stereoisomers (R and S).



                      CHEM2310 Ch 6                    36
         Molecules with >2 Stereocenters


                  Stereoisomers:
   a) (2R,3R)-2-amino-3-hydroxybutanoic acid
   b) (2R,3S)-2-amino-3-hydroxybutanoic acid
   c) (2S,3R)-2-amino-3-hydroxybutanoic acid
   d) (2S,3S)-2-amino-3-hydroxybutanoic acid


     Notice that when there are 2 stereocenters,
             there are 4 stereoisomers:
2 possible configurations (R and S) on the 1st center
2 possible configurations (R and S) on the 2nd center
                    CHEM2310 Ch 6                       37
          Molecules with >2 Stereocenters

                 2,3-dichlorobutane:
 This gives us the maximum number of stereoisomers




But it doesn’t take into consideration meso compounds
so it gives us the maximum number of stereoisomers.

                     CHEM2310 Ch 6                      38
                 Molecules with >2 Stereocenters

      What is the maximum number of stereoisomers for:

a)                   b)                      c)
                                                  CH3CH(OH)COOH
                                                    lactic acid


                          ibuprofen
 tartaric acid




                           CHEM2310 Ch 6                          39
            Molecules with >2 Stereocenters



                                               cholesterol
 What is the maximum
number of stereoisomers
          for:
                                               progesterone




                             testosterone    cortisol         aldosterone




                             estradiol      cortisone

                      CHEM2310 Ch 6                                   40
Molecules with >2 Stereocenters Suggested Homework:

Chapter 6 Exercises: 18, 50 – 55, 57 – 62, 65, 66, 68 – 70




                                                      CHEM2310 Ch 6   41
   The Chiral Environment



The stereoisomers of Tartaric Acid




          CHEM2310 Ch 6              42
             The Chiral Environment




 At room temperature, (2R,3R)-3-amino-2-butanol
                   is a liquid.
 At room temperature, (2R,3S)-3-amino-2-butanol
              is a crystalline solid.
What do you know about the other 2 stereoisomers?




                   CHEM2310 Ch 6                    43
                        The Chiral Environment




                        +

   (R)-lactic acid           (R)-1-phenylethanamine


      No bonds
to the chiral centers
     are broken.

                                    an (R,R) salt

                             CHEM2310 Ch 6            44
                    The Chiral Environment




 (R)-lactic acid
        +              (R)-1-phenylethanamine
 (S)-lactic acid
(Racemic mixture)

                                  (R,R) salt
                                      +
                                   (R,S) salt



                         CHEM2310 Ch 6          45
The Chiral Environment Suggested Homework:

Chapter 6 Exercises: 19, 67abc




                                             CHEM2310 Ch 6   46
                                  Review: Isomerism

                                          Isomers
                       Different compounds – same molecular formulas
                             (all isomers are nonsuperimposable)



    Constitutional Isomers                                Stereoisomers
Isomers – atoms have different connectivity      Isomers – atoms have same connectivity
                                                    – atoms differ in 3D arrangement



                                              Enantiomers              Diastereomers
                                               Stereoisomers              Stereoisomers
                                               – mirror images          – not mirror images



                                                                   Cis-Trans Isomers
                                                                         Stereoisomers
                                                                       – rings and alkenes
                                        CHEM2310 Ch 6                                        47
                     Review: Isomerism

  Determine: Isomers? Stereoisomers? Constitutional Isomers?
Stereoisomers? Enantiomers? Diastereomers? Cis-Trans Isomers?
  a)




   b)




                         CHEM2310 Ch 6                     48
                     Review: Isomerism

  Determine: Isomers? Stereoisomers? Constitutional Isomers?
Stereoisomers? Enantiomers? Diastereomers? Cis-Trans Isomers?
  a)




   b)




                         CHEM2310 Ch 6                     49
                     Review: Isomerism

  Determine: Isomers? Stereoisomers? Constitutional Isomers?
Stereoisomers? Enantiomers? Diastereomers? Cis-Trans Isomers?
  a)




   b)




                         CHEM2310 Ch 6                     50
                     Review: Isomerism

  Determine: Isomers? Stereoisomers? Constitutional Isomers?
Stereoisomers? Enantiomers? Diastereomers? Cis-Trans Isomers?
  a)




   b)




                         CHEM2310 Ch 6                     51
Review: Isomerism Suggested Homework:

Chapter 6 Exercises: 20, handout

Additional Problems: 41, 63




                                        CHEM2310 Ch 6   52

								
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