What is the pKa of a primary amine?

We have previously seen that ammonia has a pKa value of about 38, and is a very weak acid. Primary and secondary amines have pKa’s of very similar magnitude. Consequently, such amines are much more basic (pKb about 4) than they are acidic (pKa 38), so that their aqueous solutions are rather strongly alkaline.

What is the pKa of NH?

This time, we can find both HCl and NH3 on the pKa table. But HCl has a pKa of (–8) and NH3 has a pKa of 38.

What makes an amine more basic?

The basicity of an amine is increased by electron-donating groups and decreased by electron-withdrawing groups. The basicity of heterocyclic amines depends on the location of the electron pair of the nitrogen atom, its hybridization, and whether or not resonance stabilization is possible.

What is the pKa of amino acids?

Compounds such as amino acids that can act as either an acid or a base are called amphoteric. The basic amino group typically has a pKa between 9 and 10, while the acidic α-carboxyl group has a pKa that is usually close to 2 (a very low value for carboxyls).

What is PKA in chemistry?

pKa is by definition a -log(Ka), where Ka is the dissociation constant of an acid. Let’s look at the most iconic acid in chemistry: hydrochloric acid (HCl): In this reaction, HCl dissociates giving you a proton/hydronium ion (depending on the media) and chloride anion.

Is amine an acid or base?

Amines are bases; they react with acids to form salts. Salts of aniline are properly named as anilinium compounds, but an older system is used to name drugs: the salts of amine drugs and hydrochloric acid are called “ hydrochlorides .”. Heterocyclic amines are cyclic compounds with one or more nitrogen atoms in the ring.

What is the pKa of ammonia?

The pKa for ammonia is ~37. Therefore, because the pKa of water is lower than ammonia, it is a stronger acid the ammonia and will donate protons to the ammonia base. This reaction leads water to become the conjugate base OH- and ammonia to become the conjugate acid NH4+.