Question

4. Draw the lowest energy chair conformations for both of the following compounds. Which is more stable? Briefly explain. (8pts) 18 II llora nobsefoin smw.odo a) I c) Both have the same stability b) п 5. Draw the lowest energy chair conformations for both of the following compounds. Which is more stable? Briefly explain (8pts) beuo zed n bos enonsmothop beagndoa ow odb TotoKD ( .a1alil o enoemogoo boaee.ove dos 10 d II a) I b) II c) Both have the same stability

Answer 1

In the chair form of the cyclohexane compound if there is a substitute on the axial position , then interaction between the axial hydrogen and that axial substitution creates an steric interaction. This is called  1,3 axial interaction .

On the other hand, for equatorial substituted compound, there is no such 1,3 axial interaction.

So, equatorially substituted compound is more stable than that of axially substituted compound.

Now, higher the stability lower will be in the energy level.

The detail is shown below.

4) Compound ll is more stable. The detail explanation is shown below.

HX CH₂ 4. CH3 loy ( 13 anial interaction present) CM2 CH3. H. H. ( Two - udz (Two ly groups are in asial position) groups are in equatorial position). For compoundas, both the isomers a and 'b' are in same energy level. For compoundal aa isomen (a) is more energitic than that of ee isomer (₂) Since in 'b', there is no storic 113- diansial interaction. The latter is Bettreen (1) and " more stable than the former.

5) Compound ll is more stable. The detail explanation is shown below.

5. itz iromery leaisomer) ext etty lan' isomer) ee isomer) For Compoundes ea isomers are interactions. both are isomers and contain 1,3 diental For compound t I aa isomer condening diensial interaction but ee inomer is does not lonterin 113 dianial interaction so than ee isomer is more stable an isomer. Again compound-I is more stable compound as. than