Triethylamine, (CH3CH2)3N, is very slightly soluble in water but readily soluble (with stirring) in 1.5 M HCL.
Amines (organic bases) react with HCl to form ammonium salts. Organic salts dissolve in water.
The solubility of a substance in a particular solvent depends on various factors, including the nature of the solute and solvent, temperature, pressure, and the presence of other substances in the solution. In the case of triethylamine (C6H15N), it is considered a weak base and a nonpolar compound.
When triethylamine is placed in water, which is a polar solvent, it exhibits limited solubility. This limited solubility is due to the weak intermolecular forces between the nonpolar triethylamine molecules and the polar water molecules. The polar water molecules are more attracted to each other through hydrogen bonding than to the nonpolar triethylamine molecules.
However, when triethylamine is mixed with 1.5 M hydrochloric acid (HCl), it becomes readily soluble with stirring. HCl is a strong acid and a polar compound. The polar nature of HCl allows it to interact with both water and triethylamine molecules through ion-dipole interactions. The acid-base reaction between triethylamine and HCl produces the triethylammonium chloride salt, which is more soluble in water due to the stronger ionic interactions with the polar solvent.
Therefore, the solubility of triethylamine is enhanced in 1.5 M HCl compared to water due to the presence of a strong acid that forms a soluble salt with the weak base triethylamine.
The solubility of a compound in water or any other solvent depends on various factors, including the nature of the compound and the solvent, as well as intermolecular forces between the molecules.
In the case of triethylamine (C6H15N), it is a base and reacts with water to form an ammonium ion and hydroxide ion:
(CH3CH2)3N + H2O ⇌ (CH3CH2)3NH+ + OH-
Since this reaction occurs, the solubility of triethylamine in water is limited. Triethylamine is classified as only slightly soluble in water because only a small amount of it reacts and dissolves.
However, when triethylamine is mixed with hydrochloric acid (HCl), a different reaction occurs:
(CH3CH2)3N + HCl ⇌ (CH3CH2)3NH+Cl-
The reaction between triethylamine and HCl produces a salt called triethylammonium chloride, which is highly soluble in water. The chloride ion (Cl-) from the hydrochloric acid balances the charge of the triethylammonium ion (C6H15NH+), allowing it to dissolve readily in water.
So, when triethylamine is mixed with 1.5 M HCl (meaning a 1.5 molar solution of hydrochloric acid), the reaction with HCl drives the dissolution of triethylamine, making it soluble in the resulting solution. Stirring the mixture promotes contact between triethylamine and HCl, aiding the reaction and dissolution process.