Stereochemistry Lecture 1
38 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

When naming compounds containing multiple chiral atoms, what is the correct way to specify the configuration?

  • List the chiral atoms in descending order, separated by dashes.
  • List the chiral atoms in alphabetical order, separated by semicolons.
  • Give the configuration around each chiral atom in numerical order, separated by commas, all in parentheses at the start. (correct)
  • State the configuration of the first chiral atom, followed by the others in alphabetical order.

    • What is the correct configuration for the compound 2-bromo-3-chlorobutane?

  • (2R, 3R)-2-bromo-3-chlorobutane
  • (2S, 3R)-2-bromo-3-chlorobutane
  • (2S, 3S)-2-bromo-3-chlorobutane (correct)
  • (2R, 3S)-2-bromo-3-chlorobutane

    • What do the terms 'Z' and 'E' represent in geometric isomers?

  • Optical activity and asymmetric induction
  • Together and opposite in German (correct)
  • Stereochemistry and chirality
  • Cis and trans configurations

    • How do you determine the configuration of geometric isomers?

    <p>By looking at the highest priority group on both sides of the double bond</p> Signup and view all the answers

    What is the correct notation for specifying the configuration of multiple chiral atoms?

    <p>(number, configuration) format</p> Signup and view all the answers

    What is the purpose of specifying the configuration of chiral atoms in a compound?

    <p>To differentiate between isomers</p> Signup and view all the answers

    What is stereochemistry?

    <p>The study of 3-dimensional properties and reactions of molecules</p> Signup and view all the answers

    What are isomers?

    <p>Compounds with identical molecular formulas but different structural formulas</p> Signup and view all the answers

    What are stereoisomers?

    <p>Compounds with the same connectivity, but different arrangement in space</p> Signup and view all the answers

    What is optical isomerism?

    <p>A form of stereoisomerism in which molecules differ only in the spatial orientation of atoms</p> Signup and view all the answers

    What is a chiral carbon atom?

    <p>A carbon with four different bonded groups</p> Signup and view all the answers

    What is an enantiomer?

    <p>A type of stereoisomer that is a non-superimposable mirror image</p> Signup and view all the answers

    When does a carbon atom become superimposable on its mirror image?

    <p>When it has two or more identical groups</p> Signup and view all the answers

    How many chiral carbon atoms are in 2,4-dimethyl hexane?

    <p>2</p> Signup and view all the answers

    What is the description of light that is vibrating in all possible planes?

    <p>Unpolarized</p> Signup and view all the answers

    What is the physical property of an optically active compound?

    <p>Specific rotation</p> Signup and view all the answers

    What is the formula for determining the maximum number of optical isomers?

    <p>2n</p> Signup and view all the answers

    What is the characteristic of diastereomers?

    <p>They differ in all physical properties</p> Signup and view all the answers

    What is the definition of epimers?

    <p>Diastereomers that are different at only one chiral center</p> Signup and view all the answers

    What is the description of light that is oscillating in only one plane?

    <p>Plane polarized</p> Signup and view all the answers

    What is the difference between enantiomers and diastereomers?

    <p>Enantiomers have opposite configurations at all chiral centers, while diastereomers have opposite configurations at some chiral centers</p> Signup and view all the answers

    What is the unit of measurement for the length of the sample tube in specific rotation?

    <p>Decimeters</p> Signup and view all the answers

    What is the characteristic of a meso compound?

    <p>It has more than one chiral center and is superimposable on its mirror image</p> Signup and view all the answers

    What is the condition for a compound to be optically active?

    <p>It must be chiral in its overall structure</p> Signup and view all the answers

    What is unique about the two structures on the right in the figure of tartaric acid?

    <p>They are identical</p> Signup and view all the answers

    What type of isomerism can cyclic compounds exhibit?

    <p>Both geometric and enantiomerism</p> Signup and view all the answers

    What is the characteristic of a cyclic compound with two dissimilar chiral carbon atoms?

    <p>It has two possible enantiomeric pairs</p> Signup and view all the answers

    What is the example of a cyclic compound that exhibits enantiomerism and geometric isomerism?

    <p>1-bromo-2-chlorocyclopropane</p> Signup and view all the answers

    What is the characteristic of a meso compound in a cyclic structure?

    <p>It has a plane of symmetry</p> Signup and view all the answers

    What is the relationship between the two 'cis' enantiomers and the two 'trans' enantiomers in a cyclic compound?

    <p>They are diastereomers</p> Signup and view all the answers

    What is the ratio of potency in raising blood pressure between L-epinephrine and D-epinephrine?

    <p>20:1</p> Signup and view all the answers

    Which of the following statements is true about carvone?

    <p>It is an enantiomer responsible for spearmint odor</p> Signup and view all the answers

    What is the purpose of a polarimeter?

    <p>To measure the optical activity of a chiral sample</p> Signup and view all the answers

    What is the unit of measurement for specific rotation?

    <p>Degrees</p> Signup and view all the answers

    What is the relationship between the specific rotation of enantiomers?

    <p>They are equal in magnitude but opposite in sign</p> Signup and view all the answers

    Which of the following factors does the degree of rotation depend on?

    <p>All of the above</p> Signup and view all the answers

    What is the formula to calculate specific rotation?

    <p>[α]D = observed rotation / (pathlength x concentration)</p> Signup and view all the answers

    What is the specific rotation of (-)-lactic acid?

    <p>-3.82</p> Signup and view all the answers

    Study Notes

    Optical Activity and Stereochemistry

    • Light can be described as a wave vibrating perpendicular to its direction of propagation, and can be unpolarized or plane polarized.
    • Specific rotation is a physical property of an optically active compound, calculated by dividing the observed rotation by the length of the sample tube and the concentration of the sample.
    • Stereoisomers with two chiral carbon atoms can have enantiomers and diastereomers.

    Diastereomers

    • Diastereomers are stereoisomers that are not mirror images of each other.
    • They differ in all physical properties and can have opposite configurations at some, but not all, chiral centers.

    Meso Compounds

    • Meso compounds have two or more chiral centers and are optically inactive due to internal compensation.
    • They have a plane of symmetry and can have identical substitution on both chiral centers.

    Optical Isomerism in Cyclic Compounds

    • Cyclic compounds can exhibit enantiomerism and geometric isomerism.
    • A cyclic compound with two dissimilar chiral carbon atoms can have two enantiomeric pairs.

    Stereochemistry

    • Stereochemistry refers to the 3-dimensional properties and reactions of molecules.
    • Isomers are compounds with identical molecular formulas but different structural formulas.

    Optical Isomerism

    • Optical isomerism occurs when molecules differ only in the spatial orientation of atoms, not in their arrangement.

    Chiral Carbon Atoms, Enantiomers, and Racemic Mixtures

    • A carbon with four different bonded groups is called a chiral carbon atom, chirality center, or stereocenter.
    • A chiral carbon atom can exist in either of two three-dimensional arrangements that are non-superimposable mirror images (enantiomers).

    Measurement of Optical Activity

    • Optical activity can be measured using a polarimeter, which operates on the principle of rotating plane-polarized light.
    • Specific rotation is defined as the observed rotation of an optically active compound in a cell with a 10 cm path using light from sodium metal vapor (589 nm).

    Specification of Configuration

    • When naming compounds containing multiple chiral atoms, the configuration around each chiral atom must be specified in numerical order, separated by commas, all in parentheses at the start.
    • For geometric isomers, the configuration is determined by the priority of the groups attached to the double bond, with the highest priority group on the same side being termed Z (zusammen) and on opposite sides being termed E (entgegen).

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    This quiz covers the basics of stereochemistry, including the properties and reactions of molecules, isomers, and stereoisomers.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser