Chapter 14.25, Problem 30P

Interpretation Introduction

Interpretation:

The number of rings present in each of the given compounds are to be determined.

Concept Introduction:

The formula of hydrogen deficiency index, $\text{IHD}$ is calculated as

$\text{IHD}=\frac{\text{1}}{\text{2}}\left({\text{C}}_n{\text{H}}_{2n+2}-{\text{C}}_n{\text{H}}_x\right)$

Here, ${\text{C}}_n{\text{H}}_{2n+2}$ and ${\text{C}}_n{\text{H}}_x$ are the general molecular formulas of the alkane compound and the given compounds respectively.

The number of hydrogen atom in a ring or a double bonded organic molecule is always less by two hydrogen atoms than that of the alkane having the same number of carbon atoms.

A triple is possible only if the index of hydrogen deficiency is two or more.

A halogen atom in the formula are consider as hydrogen and presence of oxygen does not affect the $\text{IHD}$.

Oxygen atoms do not disturb the index of hydrogen deficiency and a halogen substituent is treated as a hydrogen.

If a nitrogen is present, the number of hydrogens in the formula is reduced by one.

Once the index of hydrogen deficiency is determined, the possible number of double and triple bonds and rings in the structure can be predicted.

If the index of hydrogen deficiency is one, only a double bond or a ring is possible in the structure.