Q2. Answer any TWO of the following parts: (a) Draw the two main conformations that exist for cyclohexane. Explain clearly why one conformer is more stable than the other. Using cis-1-ethyl-3-methylcyclohexane, as an example, explain how ring flipping occurs. Draw both conformers of cis-1-ethyl-3-methylcyclohexane and explain clearly which one predominates. (b) What is polarimetry? The specific rotation of (R)-carvone is - 61°. A chemist prepared a 750 mg mixture of (R)-carvone and its enantiomer in 10 ml of ethanol and placed the solution in a 10 cm polarimeter cell. The observed rotation was - 4.125°. Calculate the specific rotation for the above mixture. What is meant by enantiomeric excess? Then determine the % enantiomeric excess (% ee) in the mixture. (i) (ii) (iii) What % of the mixture is (R)-carvone and (S)-carvone?

Q2. Answer any TWO of the following parts: (a) Draw the two main conformations that exist for cyclohexane. Explain clearly why one conformer is more stable than the other. Using cis-1-ethyl-3-methylcyclohexane, as an example, explain how ring flipping occurs. Draw both conformers of cis-1-ethyl-3-methylcyclohexane and explain clearly which one predominates. (b) What is polarimetry? The specific rotation of (R)-carvone is - 61°. A chemist prepared a 750 mg mixture of (R)-carvone and its enantiomer in 10 ml of ethanol and placed the solution in a 10 cm polarimeter cell. The observed rotation was - 4.125°. Calculate the specific rotation for the above mixture. What is meant by enantiomeric excess? Then determine the % enantiomeric excess (% ee) in the mixture. (i) (ii) (iii) What % of the mixture is (R)-carvone and (S)-carvone?

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

See similar textbooks

Similar questions

On the following energy diagram, identify the energy level of the cyclohexane conformation shown in the box. Energy (kJ/mol) A) I B) II CLU ||| IV Conformations 2
5.There are two important methods that are used to prepare alkenes: they are: . and . Your answer
Consider the tricyclic structure B. (a) Label each substituent on the rings as axial or equatorial. (b) Draw B using chair conformations for each six-membered ring. (c) Label the atoms on the ring fusions (the carbons that join each set of two rings together) as cis or trans to each other.
For each attached compound drawn below:a.) Draw representations for the cis and trans isomers using a hexagon for the six-membered ring, and wedges and dashed wedges for substituents.b.) Draw the two possible chair conformations for the cis isomer. Which conformation, if either, is more stable?c.) Draw the two possible chair conformations for the trans isomer. Which conformation, if either, is more stable?d.) Which isomer, cis or trans, is more stable and why?
For the following two pairs of molecules, (1) Draw out the chair conformation for each molecule, flip the ring if it is possible. (2) Compare both molecules to circle out which one is more stable. (3) Identify their relationship as: constitutional isomer, conformational isomer, stereoisomer or identical. (4) Find all the chiral center on each molecule and label them. VS. ****
Use Newman Projections to represent the conformers of 1,2-dichloropropane and 2-bromo-3-methybutane. (Draw the Newman Projections of these conformers and add respective photos in the space provided below) Conformers of 1,2-dichloropropane 2. Conformers of 2-bromo-3-methylbutane
How do you account for the difference in energies between the two staggered conformations of 1,2-dichloroethane? How about for the two eclipsed conformations? Draw all four conformations and, on your drawing, indicate sources of strain – torsional, steric (gauche), steric eclipsed.
(a) What is the IUPAC name for the following molecule (including absolute configurations if required)? (b) Draw the Newman projections looking down the C3-C4 bond that represent all the three staggered conformations for the molecule shown above. (c) Given that the strain energies below, calculate the strain energies for each conformer and identify which is the most stable. Gauche interaction Strain Energy HOCH3 0.0 kJ mol- HOCH;CH; |0.4 kJ mol- 3.8 kJ mol- | 4.3 kJ mol- CH;CH3 CH;CH2CH3 |CH2CH; CH2CH; 4.6 kJ mol- Newman Projection of Conformer 1 Strain Energy of Conformer 1 Newman Projection of Conformer 2 Strain Energy of Conformer 2 Newman Projection of Conformer 3 Strain Energy of Conformer 3
The following name given is incorrect or incomplete, but it represents a real structure. Draw structure and name it correctly.(a) 2-cyclohexylbutane
• Question 3: a) Draw the three staggered and three eclipsed conformations that result from rotation around the designated bond using Newman projections. b) Label the most stable and least stable conformation. rotation here H CH3 C CH₂CH3 CH3
Give your view on boat conformation of cyclohexane ?
Draw the two chair conformations of the following substituted cyclohexanes. In each case, label the more stable conformation.(a) cis-1-ethyl-2-methylcyclohexane