Answer:
Interpretation: The most stable chair conformation of menthol is to be drawn labeling each substituent as axial or equatorial. Concept introduction: Among the disubstituted cyclohexanes, 1,2- cis, 1,3- trans and 1,4-cis substituents will have axial and equatorial arrangements.
Explanation:
1 &2. The most stable chair conformation for each menthol is the one which places the bulky isopropyl group in the
equatorial position, thereby avoiding an unfavorable 1,3-diaxial interaction to it. The more stable conformer is
indicated (image attached) by the relative lengths of the reversible arrows. Neoisomenthol probably exists at equilibrium
with substantial amounts of both conformers, since the chair conformation which places the isopropyl group in an
equatorial position places both the methyl and hydroxy groups in axial positions. (next page)
3. Consideration of the most stable chair conformation of each of the diastereomeric menthols suggests that menthol
itself (first diastereomer shown) should be the most stable of the four. Menthol itself is the only diastereomer of the
four in which all three substituents on the cyclohexane ring may assume an equatorial position simultaneously.
4. Yes, all four of the diastereomeric menthols would have of optical activity. The absolute configuration of each
chiral carbon in the menthols has been specified as R or S in the planar projections (next page).
5. In table 4-3, the ΔG° values given are for an equatorial to axial transition (which is why the values are all
positive). The overall ΔG° is the sum of equatorial to axial (+ΔG°) and axial to equatorial (-ΔG°) values. The
estimated ΔG° values for the transitions in the directions shown are: menthol = (1.70 + 0.94 + 2.20) = 4.84 kcal/mol;
isomenthol = (1.70 – 0.94 – 2.20) = -1.44 kcal/mol; neomenthol = 2.96 kcal/mol; neoisomenthol = 0.44 kcal/mol.
The hydroxyl group is trans to the isopropyl group. The hydroxyl group is cis to the methyl group.
When cyclic alkanes form rings, a strain is imposed on the molecule. In order to relieve this strain, Sache and Mohr(1918) proposed that the strain is relieved if all the carbon atoms are not forced into one plane. The rings must be seen as puckered.
The most stable puckered form of 2−isopropyl−5−methylcyclohexanol structure is the chair conformation. The atoms or groups that lie perpendicular to the pane of the ring are called "axial" while atoms or groups are called "equatorial".
In 2−isopropyl−5−methylcyclohexanol, We can see from the structure that the hydroxyl group is trans to the isopropyl group. The hydroxyl group is cis to the isopropyl group.
Learn more: https://brainly.com/question/11969651
