Chapter 12, Problem 12.33UKC

Interpretation Introduction

Interpretation:

For the below compound the chirality centers has to be labeled and number of chiral centers and the type of alcohol should be determined.

Concept introduction:

Chirality center:

When a carbon atom is bonded to four different groups, then that carbon is named as chiral carbon and it is called as chirality center. Generally, the carbon atom contains tetrahedral valency, therefore it bonded to four atoms or molecules. The chiral center is bonded with four different elements or groups. If the single carbon atom is bonded to two or more identical group or atom, then it is also not considered as chiral carbon. In addition to this, if the carbon atom contains multiple bond then it does not able to bond with four different groups then it is not considered to be as a chirality center.

Classification of alcohol:

Generally the alcohol group is bonded with minimum one alkyl group. The alcohol group is classified into three types, such as primary $(1^{\circ })$, secondary $(2^{\circ })$ and tertiary $(3^{\circ })$. It depends on number of carbons attached to the single carbon atom bonded with the alcohol group. Primary $(1^{\circ })$ alcohol contains one carbon bonded with alcohol attached carbon atom. Secondary $(2^{\circ })$ alcohol contains two carbon bonded with alcohol attached carbon atom. Tertiary $(3^{\circ })$ alcohol contains three carbon bonded with alcohol attached carbon atom.

Explanation of Solution

Given compound is norepinephrine,

In the given drug (i,e) norepinephrine, the ${\text{CH}}_2$ group is not a chiral center as it contains more than one hydrogen atom. As the benzene ring contains the double bond it also cannot be considered as chiral center. Only the one carbon atom bonded with four different groups as shown below indicates that, the given compound has one chirality center.

In the below compound, $\text{OH}$ group attached carbon atom is bonded with two carbon atoms, therefore it is secondary $(2^{\circ })$ alcohol.