The lone pair of amines makes them basic. They react with acids to form acid-base salts. Amines are more basic than alcohols, ethers and water. When an amine is dissolved in water, an equilibrium is established, where water acts as an acid and transfer a proton to the amine. The basic strength of an amine can be measured by basicity constant K b . Arylamines are less basic than alkylamines because the lone pair of nitrogen is delocalised with the aromatic ring and are less available for donation. Substituted arylamines can be either more basic or less basic than aniline, depending on the substitutent. ERG substituents, such as –CH 3 , –NH 2 and –OCH 3 increases the basicity and EWG substituents, such as –Cl, –NO 2 and –CN decreases basicity. While sp 2 -hybridized nitrogen atom in pyridine is less basic than the sp 3 -hybridized nitrogen in an alkylamine.

(i) Select the correct order of K b .