Concept explainers
(a)
Interpretation: All the staggered and eclipsed conformations of each given molecule that would result from the rotation around the highlighted bond are to be drawn.
Concept introduction: Conformational isomers are defined as the type of stereoisomers in which the rotation about single bonds forms different spatial arrangements of atoms. It is of two types, eclipsed conformation and staggered conformation.
In Newman projection, the carbon in front is represented by a point and in the back is represented by a circle.
(b)
Interpretation: The graphs of energy versus dihedral angle for rotation around the highlighted bond of each given molecule are to be drawn.
Concept introduction: Newman projection is a visual representation of a conformation. It describes three groups which are attached to each carbon atom in a particular
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Organic Chemistry
- (a) Using Newman projections, draw all staggered and eclipsed conformations that result from rotation around the indicated bond in each molecule; (b) draw a graph of energy versus dihedral angle for rotation around this bond. [1] CH3CH₂ CH₂CH₂CH3 [2] CH3CH₂ CHCH₂CH3 TCH₂arrow_forward(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 3arrow_forwardDraw the most stable conformer of the following molecule. (A solid wedge points out of the plane of the paper toward the viewer. A hatched wedgepoints back from the plane of the paper away from the viewer.)arrow_forward
- QUESTION 3 (a) Draw the two conformations of ethane which has an energy minimum and energy maximum using the Newman projection. Explain why one conformation is lower in energy than the other.arrow_forwardDraw the most stable conformer of the following molecule. (A solid wedge points out of the plane of the paper toward the viewer. A hatched wedge points back from the plane of the paper away from the viewer.)arrow_forwarda) i) Draw the Newman projections for the conformations of ethane (staggered and eclipsed) Which is higher in energy? Which is more stable? Next to each conformer, draw the equivalent ‘sideways’ view, using wedged bondsarrow_forward
- 3)) Draw the most stable chair conformation of a 1,2,4-trimethylcyclohexane (Show all the hydrogens and indicate if the bond is axial or equatorial at the substitution).arrow_forward(iii) Draw the lowest energy conformer for the following compound.arrow_forwardDraw the most and least stable conformer of chloroethane and 1,2-dibromoethane.arrow_forward
- 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. ****arrow_forwardpusa) Draw and label the cis and trans isomers of 3-methyl-isopropyl cyclohexane (flat ring with wedges and/or dashes). IS to of to b) Draw the chair and "flipped" chair conformations of the cis isomer. Which is more stable? c) Draw the chair and "flipped" chair conformations of the trans isomer. Which is more stable?arrow_forwardDraw the Newman projection so that it corresponds to the molecule and conformation shown when viewed down the red bond in the direction of the arrow.arrow_forward
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