How do electron-withdrawing groups affect basicity?

The basicity of an amine is increased by electron-donating groups and decreased by electron-withdrawing groups. Aryl amines are less basic than alkyl-substituted amines because some electron density provided by the nitrogen atom is distributed throughout the aromatic ring.

Why do electron-withdrawing groups decrease basicity?

Electron-withdrawing groups decrease the electron density of the benzene ring, making the arylamine less basic than aniline.

Which nitrogen of histidine is more basic?

The difference can be seen by looking at the pKa’s of the conjugate acids in each case. The higher the pKa of the conjugate acid, the more tightly the proton is held, and so the more basic the nitrogen atom. Arginine is by far the most basic and histidine is the least basic. Figure AB15.

Why is propylamine more basic?

Overall there seems to be a consensus that propylamine is slightly more basic than methylamine at the same temperature but there is very little difference. Theoretically this can be explained by the slightly greater inductive effect of the propyl group versus the methyl group.

Why is histidine less basic?

Lysine has two amine groups, which makes it overall basic because of the second isolated amine group (−(CH2)4NH2). Histidine, on the other hand, contains imidazole group, which is also basic. (see the chart), thus, lysine is considered to be more basic than histidine in physiological conditions.

Why is histidine considered basic?

At a pH superior to their pK (Table 2), the amine side chains are uncharged. At a pH inferior to their pK, the lysine, arginine and histidine side chains accept an H+ ion (proton) and are positive charged. They are therefore basic.

Which compound has highest basicity?

So, the compound benzylamine is the most basic compound among the given options.

How does basicity increase down the group?

As the atomic radius lowers, the ionisation energy decreases, implying that the tendency to lose electrons increases, implying an increase in metallic character ( as electron affinity also decreases).