Chapter 8, Problem 3Q

Interpretation Introduction

(a)

Interpretation:

The missing C₃H₅ and OH substituents needs to be added to the template in order to get one possible chair conformation for each compound.

Concept Introduction:

Chair-like conformation for cyclohexane molecule is a three-dimensional way of representing the molecule. This is a non-planar conformation with all the angles approximately equal to 109.5^o. This is stable conformation because it has lower strain energy than the flat hexagonal shape. All the carbon centers are equivalent in the chair conformation. In the flat hexagonal shape, the wedge and dashed bonds represent the group attached directed away and towards the plane of paper respectively. In the chair conformation, these wedge and dashed bonds are axial and equatorial respectively.

Interpretation Introduction

(b)

Interpretation:

The most appropriate method from MM2 or MOPAC to determine whether compound 1 or 2 is most stable product in each reaction needs to be determined.

Concept Introduction:

Computational chemistry uses computer simulation to monitor solution of chemical problems. The theoretical chemistry is used in which efficient computer programs are incorporated to determine the structures and properties of molecules.

In the computational chemistry, the MM2 and MOPAC methods are defined as follows:

MM2:

This method is developed mainly for conformational analysis of small organic compounds such as hydrocarbons. This is designed to reproduce the equilibrium covalent geometry of molecules as close as possible.

MOPAC:

This is a computer program used in the computational chemistry for semi-empirical quantum chemistry algorithms. It runs on Mac, Windows and Linux.

Interpretation Introduction

(c)

Interpretation:

The number of chair-like conformation for the energy minimization needs to be determined. The alcohol and alkene substituent need to be described orientated as axial or equatorial.

Concept Introduction:

Chair-like conformation for cyclohexane molecule is a three-dimensional way of representing the molecule. This is a non-planar conformation with all the angles approximately equal to 109.5^o. This is stable conformation because it has lower strain energy than the flat hexagonal shape. All the carbon centers are equivalent in the chair conformation. In the flat hexagonal shape, the wedge and dashed bonds represent the group attached directed away and towards the plane of paper respectively. In the chair conformation, these wedge and dashed bonds are axial and equatorial respectively.

Interpretation Introduction

(d)

Interpretation:

The input structure for compound 1 needs to be determined.

Concept Introduction:

Computational chemistry uses computer simulation to monitor solution of chemical problems. The theoretical chemistry is used in which efficient computer programs are incorporated to determine the structures and properties of molecules.

MM2 method is developed mainly for conformational analysis of small organic compounds such as hydrocarbons. This is designed to reproduce the equilibrium covalent geometry of molecules as close as possible.

The compound 1 is given as follows:

  

The chair conformation is represented as follows:

  

Here, both C₃H₅ and OH groups are at axial positions.

Thus, the input for compound 1 is represented as follows:

  

Interpretation Introduction

(e)

Interpretation:

The input structure for compound 2 needs to be determined.

Concept Introduction:

Computational chemistry uses computer simulation to monitor solution of chemical problems. The theoretical chemistry is used in which efficient computer programs are incorporated to determine the structures and properties of molecules.

MM2 method is developed mainly for conformational analysis of small organic compounds such as hydrocarbons. This is designed to reproduce the equilibrium covalent geometry of molecules as close as possible.