In an aqueous solution, the basic strength of methyl-substituted amines does not strictly follow the — GOC and Organic Chemistry Basics Chemistry Question
Question
In an aqueous solution, the basic strength of methyl-substituted amines does not strictly follow the inductive effect trend due to competitive solvation and steric factors. What is the experimentally determined correct decreasing order of basic strength in water?
💡 Solution & Explanation
In the aqueous phase, basicity depends on a delicate balance of $+I$ effect, hydrogen bonding stabilization of the conjugate acid (solvation), and steric hindrance. For methylamines, the secondary amine is the most basic, followed by primary, then tertiary (which suffers from severe steric hindrance preventing optimal hydrogen bonding), and finally ammonia. The order is $2^\circ > 1^\circ > 3^\circ > NH_3$.