Tertiary amino group is found in:

Benadryl

The correct answer is option 3. Benadryl.

Let us break down the explanation of why Benadryl (Diphenhydramine) contains a tertiary amino group and the other compounds do not.

A tertiary amine is a nitrogen atom bonded to three alkyl or aryl groups with no hydrogen atoms attached to the nitrogen.

Analysis of the Given Compounds:

1. Estrogen:

Estrogen is a steroid hormone made up of a fused ring system, mainly containing carbon, hydrogen, and oxygen atoms. It does not have an amine group (no nitrogen atom in its structure). Since there is no nitrogen atom in estrogen, it does not have a tertiary amino group.

2. Ephedrine:

Ephedrine has a nitrogen atom that is attached to two groups: one carbon-containing group and one hydrogen atom. This means ephedrine has a secondary amine, where nitrogen is bonded to two substituents and one hydrogen. Secondary amine, not tertiary.

3. Benadryl (Diphenhydramine):

Benadryl contains a nitrogen atom that is bonded to three groups: two benzyl groups (\(C_6H_5CH_2\)) and one methyl group (\(CH_3\)). Because the nitrogen is attached to three carbon-containing groups, it is a tertiary amine.

4. Adrenaline (Epinephrine):

Adrenaline has a nitrogen atom bonded to two carbon-containing groups and one hydrogen atom. This makes it a secondary amine, not a tertiary amine.

Why Benadryl Contains a Tertiary Amine:

In Benadryl, the nitrogen atom is attached to three carbon-containing groups (two benzyl groups and one methyl group), which classifies it as a tertiary amine because there are no hydrogen atoms attached to the nitrogen.

Thus, Benadryl (Diphenhydramine) is the only compound in the list that contains a tertiary amino group.