Question

Aromatic amines are insoluble in water because:
A.Due to the larger hydrocarbon part which tends to retard the formation of H-bonds
B.Due to the larger hydrocarbon part which tends to retard the formation of H-Nbonds
C.Due to the larger hydrocarbon part which tends to retard the formation of H-Cbonds
D.None of these

Answer 1

In any amine, there is always a large hydrocarbon group present attached to the nitrogen atom. The general formula of amine is ${{R}_{1}}N{{H}_{2}}$ , thus there can be more than one group of hydrocarbons attached to nitrogen.

Complete answer:
The correct answer to this question is option A, aromatic amines are insoluble in water due the large hydrocarbon parts present in aromatic amines.
Due to the presence of those large hydrocarbon parts, hydrogen bonding does not occur properly and thus it does not dissolve in water. The large hydrocarbon part attached to the amino group is hydrophobic, thus it becomes hard for it to dissolve in water.
Hydrogen bonding is important for solubility of any substance in water. If it is not sufficient enough, the substance will not dissolve in water.
The general formula of amine varies according to what degree of amine is. Primary amine only has the aromatic ring as the hydrocarbon part, but secondary and tertiary amine might have more than one hydrocarbon part attached to the nitrogen atom.
The more the hydrocarbon part, the harder it becomes to form hydrogen bonds (H-bond). The general formula of primary amine is ${{R}_{1}}N{{H}_{2}}$ , the general formula for secondary amine is ${{R}_{2}}N{{H}_{{}}}$ and that for the tertiary amine is ${{R}_{3}}N$ . It does not necessarily mean that the R part in an amine group will be an aromatic chain, but the way an aromatic chain has been bound also influences the retardness of forming hydrogen bonds.

Note:
The main reason for which an aromatic amine does not dissolve in water is that the large hydrocarbon part attached to it is hydrophobic, other reason include that hydrogen bonding does not occur and the more hydrocarbons get attached to it, it becomes more hydrophobic and gets more retardation towards dissolution in water.