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5.E: Stereochemistry at Tetrahedral Centers (Exercises)

  • Page ID
    61692
  • These are the homework exercises to accompany the Textmap for McMurry's Organic Chemistry textbook.

    5.2: The Reason for Handedness in Molecules: Chirality

    5.2 Exercises

    Questions

    Q5.2.1

    Identify the chiral centers in each of the following:

    Solutions

    S5.2.1

    5.3: Optical Activity

    5.3 Exercises

    Questions

    Q5.3.1

    A sample with a concentration of 0.3 g/mL was placed in a cell with a length of 5 cm. The resulting rotation at the sodium D line was +1.52°. What is the [α]D?

    Solutions

    S5.3.1

    5 cm = 0.5 dm

    [α]D = α/(c x l) = +1.52/(0.3 x 0.5) = +10.1°

    5.5: Sequence Rules for Specifying Configuration

    5.5 Exercises

    Questions

    Q5.5.1

    Orient the following so that the least priority (4) atom is paced behind, then assign stereochemistry (R or S).

    Q5.5.2

    Draw (R)-2-bromobutan-2-ol.

    Q5.5.3

    Assign R/S to the following molecule.

    Solutions

    S5.5.1

    A = S; B = R

    S5.5.2

    S5.5.3

    The stereo center is R.

    5.6: Diastereomers

    5.6 Exercises

    Questions

    Q5.6.1

    Determine the stereochemistry of the following molecule:

    Solutions

    S5.6.1

    5.7: Meso Compounds

    5.7 Exercises

    Questions

    Q5.7.1

    Which of the following are meso-compounds:

    C – 2,3-dibromobutane

    D – 2,3-dibromopentane

    Solutions

    S5.7.1

    Compounds A and C are meso.

    5.9: A Review of Isomerism

    5.9 Exercises

    Questions

    Q5.9.1

    What kind of isomers are the following pairs:

    A – (R)-5-chlorohexene and 6-chlorohexene

    B – (2R,3R)-dibromohexane and (2R,3S)-dibromohexane

    Solutions

    S5.9.1

    A = Structural Isomers

    B = Diastereomers

    5.11: Prochirality

    5.11 Exercises

    5.11 Questions

    Q5.11.1

    State which of the following hydrogen atoms are pro-R or pro-S.

    Q5.11.2

    Identify which side is Re or Si

    5.11 Solutions

    S5.11.1

    Left compound: Ha = pro-S and Hb = pro-R

    Right compound: Ha = pro-R and Hb = pro-S

    S5.11.2

    A – Re; B – Si; C – Re; D – Si

    5.12: Chirality in Nature and Chiral Environments

    5.12 Exercises

    5.12 Questions

    Q5.12.1

    Draw the two enantiomeric forms of 2-butanol, CH3CH(OH)CH2CH3. Label their configurations.

    Q5.12.2

    Sometimes, compounds have many chiral centers in them. For the following compounds, identify four chiral centers in each, mark them with asterisks, and identify each center as R or S configuration.

    The following is the structure of dysinosin A, a potent thrombin inhibitor that consequently prevents blood clotting.

    5-12(2).png

    Ginkgolide B (below) is a secondary metabolite of the ginkgo tree, extracts of which are used in Chinese medicine.

    5-12(3).png

    Sanglifehrin A, shown below, is produced by a bacteria that may be found in the soil of coffee plantations in Malawi. It is also a promising candidate for the treatment of organ transplant patients owing to its potent immuno-suppressant activity.

    5-12(4).png

    5.12 Solutions

    S5.12.1

    5-12.png

    S5.12.2

    5-12sol(2).png

    5-12sol(3).png

    5-12sol(4).png