Chapter 2, Problem 2.64P

(a)

Interpretation Introduction

Interpretation:

The conformation of rings A, B, C and D in Cholestanol has to be described.

Concept Introduction:

The conformation structures of six membered rings are given by chair forms.  In the chair conformation, all $\text{C-C-C}$ bond angles are $\text{110}{\text{.9}}^{\text{0}}$ and the hydrogens on the adjacent carbon atoms are staggered with respect to one another.  In the chair conformation, no two atoms are closely present, so, there is a little strain present in chair conformation structure of cyclohexane.  The $\text{C-H}$ bonds in the chair conformation are arranged in axial and equatorial positions.  The bonds that are present parallel to the axis are axial bonds and the bonds that are present perpendicular to the axis are equatorial bonds.  In cyclohexane, six hydrogens are axial and six hydrogens are equatorial.

(b)

Interpretation Introduction

Interpretation:

The hydroxyl group present on Ring A is either axial or equatorial has to be given.

Concept Introduction:

The $\text{C-H}$ bonds in the chair conformation are arranged in axial and equatorial positions.  The bonds that are present parallel to the axis are axial bonds and the bonds that are present perpendicular to the axis are equatorial bonds.  In cyclohexane, six hydrogens are axial and six hydrogens are equatorial.

(c)

Interpretation Introduction

Interpretation:

The methyl group present at the junction of Ring A and Ring B is either axial or equatorial to Ring A and Ring B has to be given.

Concept Introduction:

The $\text{C-H}$ bonds in the chair conformation are arranged in axial and equatorial positions.  The bonds that are present parallel to the axis are axial bonds and the bonds that are present perpendicular to the axis are equatorial bonds.  In cyclohexane, six hydrogens are axial and six hydrogens are equatorial.

(d)

Interpretation Introduction

Interpretation:

The methyl group present at the junction of Ring C and Ring D is either axial or equatorial has to be given.

Concept Introduction:

The $\text{C-H}$ bonds in the chair conformation are arranged in axial and equatorial positions.  The bonds that are present parallel to the axis are axial bonds and the bonds that are present perpendicular to the axis are equatorial bonds.  In cyclohexane, six hydrogens are axial and six hydrogens are equatorial.