Ethylamine accepts a proton from water. As it is a weak base, an equilibrium arrow is used.

(Or written as ions: CH₃NH₃⁺Cl^–)

Two moles of amine react with one mole of diprotic sulfuric acid.

Ethylamine is a stronger base.

The ethyl group has a longer alkyl chain than methyl, resulting in a slightly greater positive inductive effect. This pushes more electron density towards the nitrogen atom, making the lone pair more available to accept a proton (H⁺).

Cyclohexylamine is a stronger base.

In phenylamine, the lone pair on the nitrogen atom becomes delocalised into the benzene ring system. This decreases the electron density on the nitrogen, making the lone pair less available to accept a proton.

Diethylamine is a stronger base.

It has two ethyl groups creating a positive inductive effect compared to only one in ethylamine. This results in a higher electron density on the nitrogen lone pair, making it more available to accept a proton.

Methylamine is a stronger base.

The alkyl group in methylamine exerts a positive inductive effect, pushing electrons towards the nitrogen. Ammonia lacks this alkyl group, so its lone pair is less electron-dense and less available to accept protons.

Methylamine is a stronger base.

Chlorine is highly electronegative and exerts a negative inductive effect (electron withdrawing). In chloromethylamine, this pulls electron density away from the nitrogen, making the lone pair less available to accept a proton.

Although the amine group can form hydrogen bonds with water, the long non-polar hydrocarbon chain (6 carbons) is hydrophobic. The Van der Waals forces between these chains are significant and disrupt the hydrogen bonding network of water, reducing solubility.

Hexylamine reacts with the acid to form an ionic salt.

The resulting alkylammonium ion (C₆H₁₃NH₃⁺) is charged and can form strong ion-dipole interactions with water molecules, making it much more soluble than the neutral molecule.

Hydroxide ions remove protons from the alkylammonium ions:

This converts the soluble ionic form back into the insoluble neutral molecule (hexaylamine), causing it to precipitate out of solution.

Order: 1 (Strongest) > 2 > 3 (Weakest)

• Amine 1 (Secondary Amine): Most basic. It has two alkyl groups pushing electrons towards the nitrogen (positive inductive effect), making the lone pair very available.
• Amine 2 (Primary Amine): Intermediate basicity. It has only one alkyl group providing a positive inductive effect.
• Amine 3 (Phenylamine derivative): Weakest base. The lone pair on the nitrogen is delocalised into the adjacent benzene ring, significantly reducing its availability to accept a proton.