Question

Question 13 1 pts Draw the lowest-energy conformer of the molecule below. How many methyl groups are axial?

Answer 1

Two methyl groups (shown in red) are in axial bonds The given isomer is the lowest energy conformer since it has bulky tertiary butyl group present on the equitorial position.

In cyclohexane chair conformation two types of bonds are present. Axial and Equitorial (Ha are axial bonds ane He are equitorial bonds) Не, He All the red colored bonds are in above the plane and all the blue colored bonds are in below the plane The substitutents that are present in equitorial bonds are stable this is because axial substituents suffer with steric interactions The two specific steric interactions that cause an axial substituents to be higher in energy than a equatorial substituent are called "diaxial interactions" For example in the below structure, the methyl substituent present at the 1st carbon will have interactions with the hydrogens present on the carbons 3 and 5. This interactions are known as 1,3-diaxial interactions which destabilizes the conformation HC In cyclohexane chair conformation substituents present on equitorial bonds are more stable and hence in the given compounds stable isomer will have substituents on equitorial bonds. PH -H V56 Questions 11 and 12 refer to the following conformers of trans-1,2-dimethylcyclohexane: CH3 HS HEHE H2 Hs 1 HC NIH HHC PH TCH, HOT Ha H, H HE Ho 11. Identify all of the equatorial hydrogen atoms in the MOST stable conformer of trans-1,2- dimethylcyclohexane: (a) Hs, H (b) H3, Hs, H8, H. (c) H, H2, H4, H., H7 H10 (d) H2, H4, H7 (e) H3, Hg (f) H, H, H10 below the plane bonds 12. Identify all hydrogen atoms having destabilizing 1,3-diaxial steric interactions in the LEAST stable conformer of trans-1,2-dimethylcyclohexane: (a) Hs, H. (b) H3, Hs, H3, H, (c) H1, H3, H., H, H, Ho (d) H3, H4, H7 (e) H3, Hg (1) H1, H, H10