Conformations of 2-Chloroethanol: Trans and Gauche Forms
30 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

What is the primary reason for the Gauche form of 2-Chloroethanol being more stable than the Trans form?

  • The staggering of bonds in the Gauche form
  • The larger bond angle in the Gauche form
  • The formation of an intramolecular H-bond (correct)
  • The increased torsional strain in the Trans form

    • What is the bond angle strain caused by in a planar cycloalkane?

  • The deviation from the ideal trigonal bond angle of 120°
  • The deviation from the ideal linear bond angle of 180°
  • The deviation from the ideal tetrahedral bond angle of 109.5° (correct)
  • The deviation from the ideal tetrahedral bond angle of 90°

    • What is the ideal dihedral angle in ethane?

  • 60°
  • 120°
  • 90°
  • 180° (correct)

    • Which type of strain is caused by the deviation from the staggered arrangement of C-H bonds?

    <p>Torsional strain</p> Signup and view all the answers

    What is the result of non-bonded interactions between atoms or groups in a cycloalkane?

    <p>Either destabilization or stabilization of the conformation</p> Signup and view all the answers

    What is the percentage of the Trans form in the solid state of 2-Chloroethanol?

    <p>73%</p> Signup and view all the answers

    What is the result of non-bonded atoms or groups crowding together?

    <p>They repel each other, resulting in van der Waals strain.</p> Signup and view all the answers

    What is the primary factor influencing the positions of non-bonded atoms or groups?

    <p>Dipole-dipole interactions</p> Signup and view all the answers

    What is the name of the strain caused by the deviation of bond angles from the ideal bond angle in cyclopropane?

    <p>Angle strain</p> Signup and view all the answers

    What is the shape of the bonding orbitals in cyclopropane?

    <p>Bent, resembling bananas</p> Signup and view all the answers

    What is the effect of eclipsing C-H bonds on adjacent carbons in cyclopropane?

    <p>Torsional strain</p> Signup and view all the answers

    What is the conformation of cyclobutane?

    <p>In equilibrium between planar and puckered conformers</p> Signup and view all the answers

    What is the estimated energy difference between the two conformers?

    <p>7.1 kJ mol−1</p> Signup and view all the answers

    What is the main reason for the instability of conformer (I)?

    <p>Steric effects due to the axial methyl group</p> Signup and view all the answers

    What is the effect of increasing the size of the substituent on the conformation of cyclohexane?

    <p>The equatorial conformer becomes more favored</p> Signup and view all the answers

    What determines the conformation of di- and poly-substituted cyclohexanes in the absence of polar effects?

    <p>Steric effects</p> Signup and view all the answers

    What is the name of the stereoisomers that can exist in disubstituted cyclohexanes?

    <p>Geometrical isomers</p> Signup and view all the answers

    How many configurational isomers can exist in 1,4-dimethylcyclohexane, and how many conformations can each exist in?

    <p>2 configurational isomers, each with 2 conformations</p> Signup and view all the answers

    What is the reason for the similar stability of trans and cis Hydrindane isomers?

    <p>The (e) bonds must not approach each other in trans Hydrindane, resulting in a puckered ring.</p> Signup and view all the answers

    Which isomer of Hydrindane has a more rigid five-membered ring?

    <p>Trans Hydrindane</p> Signup and view all the answers

    What is the effect of the (e) bonds in trans Hydrindane on the six-membered ring?

    <p>It becomes more puckered</p> Signup and view all the answers

    What is the consequence of the deformation in the chair form in cis Hydrindane?

    <p>The (1,3) axial H-atoms interactions decrease</p> Signup and view all the answers

    Why is the energy difference between cis and trans hydrindanes relatively small compared to the isomers of decalins?

    <p>Not specified in the text</p> Signup and view all the answers

    What is the term used to describe the capability of the five-membered ring in cis Hydrindane?

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

    Which of the following statements about cis-1,4-dimethylcyclohexane is correct?

    <p>Both chair conformers are equally stable</p> Signup and view all the answers

    What is the approximate energy difference between the two chair conformers of trans-1,4-dimethylcyclohexane?

    <p>3.6 kcal/mol</p> Signup and view all the answers

    Which of the following isomers of dimethylcyclohexane has equal energy for both conformers?

    <p>cis-1,2-dimethylcyclohexane</p> Signup and view all the answers

    What is the general rule for the more stable conformer of disubstituted cyclohexanes?

    <p>The larger substituent is in the equatorial position</p> Signup and view all the answers

    What is the requirement for the conformation of cis and trans 1-t-butyl-3-methylcyclohexane?

    <p>A very large tert-butyl group is required to be in the equatorial position</p> Signup and view all the answers

    What is the general trend in the conformational analysis of dimethylcyclohexane isomers?

    <p>One conformer is of much lower energy in some cases, while both conformers have equal energy in other cases</p> Signup and view all the answers

    Study Notes

    Stability of 2-Chloroethanol Forms

    • The Gauche form of 2-Chloroethanol is more stable than the Trans form due to lower steric strain from closer interaction between the chlorine atom and adjacent hydrogen atoms.
    • In the solid state, the Trans form of 2-Chloroethanol represents a small percentage, indicating a preference for the Gauche configuration.

    Cycloalkane Strain

    • Planar cycloalkanes experience bond angle strain caused by bond angles deviating from the ideal tetrahedral angle of 109.5 degrees.
    • Cyclopropane exhibits angle strain due to deviations from this ideal bond angle, impacting stability.
    • The strain experienced results from steric interactions and non-bonded interactions between substituents in the cycloalkane structure.

    Dihedral and Bonding Angles

    • The ideal dihedral angle in ethane is 60 degrees, maintaining a staggered conformation that minimizes torsional strain.
    • Eclipsing C-H bonds in cyclopropane lead to torsional strain, increasing energy and reducing stability of the molecule.

    Conformers and Cyclohexane

    • Cyclobutane adopts a non-planar conformation to alleviate angle strain and torsional strain associated with C-H eclipsing.
    • The energy difference between conformers can be estimated, reflecting the stability of staggered versus eclipsed arrangements.
    • Increasing the size of substituents on cyclohexane can influence its conformation, typically favoring equatorial positions to minimize steric hindrance.

    Isomerism and Stability

    • Di- and poly-substituted cyclohexanes exhibit various conformations based on steric interactions and substitution patterns, with axial and equatorial positions impacting stability.
    • Disubstituted cyclohexanes have two possible stereoisomers, and 1,4-dimethylcyclohexane can yield configurational isomers with distinct conformations.
    • The stability of trans and cis Hydrindane isomers is similar due to their ability to relieve steric strain, with the trans form generally more rigid due to its five-membered ring interactions affecting the six-membered ring’s conformation.

    Energy Differences and Conformational Preferences

    • The energy difference between cis and trans hydrindanes is relatively small compared to other systems like decalins due to their structural flexibility.
    • The term "conformational capability" refers to how the five-membered ring structure of cis Hydrindane can influence the overall stability and conformation.
    • In 1,4-dimethylcyclohexane, both configurational isomers exist but showcase distinct energy landscapes based on substituent positioning.
    • The more stable conformer of disubstituted cyclohexanes typically positions larger substituents in equatorial positions to minimize steric interactions.
    • Specific conformations of cis and trans 1-t-butyl-3-methylcyclohexane require considerations of steric strain, with equatorial placements being generally preferred for stability.
    • The analysis of dimethylcyclohexane isomers reveals a trend where the most stable conformer is generally the one with equatorial substituents.

    Studying That Suits You

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

    Quiz Team

    Description

    This quiz tests your understanding of the conformations of 2-chloroethanol, specifically the trans and gauche forms, including their stability and properties. Learn about the difference between the two forms and how they are affected by intramolecular hydrogen bonding.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser