Chapter 19, Problem 19.70AP

Interpretation Introduction

(a)

Interpretation:

The explaination for the observation that although biacetyl and $\text{1, 2-cyclopentanedione}$ have the same type of functional group, their dipole moments differ is to be stated.

Concept introduction:

The dipole moment of a molecule is the measure of the polarity of the chemical bonds present in that molecule. Larger is the electronegativity difference between the atoms present in the molecule, more is the polarity and more is the dipole moment of the molecule.

Interpretation Introduction

(b)

Interpretation:

The explaination for the observation that $n\to \pi *$ absorption at $280\text{ nm}$ is nearly eliminated when acetaldehyde is mixed with excess of ethanethiol is to be stated.

Concept introduction:

The UV-visible spectroscopy involves the excitation of the electrons in the molecule. In the $n\to \pi *$ transition the non bonding electrons (n) are excited to the $\pi *$ orbitals. The transition $n\to \pi *$ is a forbidden transition.

Interpretation Introduction

(c)

Interpretation:

The explanation for the observation that compound A has much weaker IR carbonyl absorption than compound B is to be stated.

Concept introduction:

Spectroscopy method is used to identify the structure of the molecule. It is based on the interactions between matter and electromagnetic radiations and IR spectroscopy is used to identify the functional group present in a compound. Each and every bond vibrates at a characteristic frequency.