Primary Amines vs. Tertiary Amines

Main Difference

The main difference between Primary Amines, and Tertiary Amines is that Primary Amines have one alkyl or aryl group attached to the nitrogen atom in their structure, whereas Tertiary Amines have three alkyl or aryl groups attached to the nitrogen atom in their structure.

Difference Between Primary Amines and Tertiary Amines

Comparison Chart

Primary Amines vs. Tertiary Amines

The structure of primary amines comprises of one alkyl group bonded to each nitrogen atom; however, for tertiary amines, the structure comprises three alkyl groups bonded to each nitrogen atom, thus leaving no hydrogen atom bonded to a nitrogen atom.

Primary amines are less basic than tertiary amines but more basic than ammonia; whereas, tertiary amines are more basic than primary amines and ammonia.

In primary amines, no considerable steric hindrance is found; but tertiary amines show steric hindrance due to the attached alkyl groups on the same nitrogen atom. While naming primary amines their alkyls or aryl groups are mentioned as a prefix; however, while pronouncing tertiary amines all of the three alkyl or aryl groups attached are needed to be mentioned in their name.

What are Primary Amines?

Primary amines are the amines that contain only one alkyl, or aryl group that is attached to the nitrogen atom in their structure as an ammonia molecule is bonded to three hydrogen atoms, one of these hydrogen atoms un-bonds with the nitrogen atom and gets replaced by an alkyl or an aryl group. An alkyl group is a functional group that is found in organic molecules.

Its structure can be explained as, as a hydrogen atom loses bond in this group, a vacant point is formed. This vacant place can be filled by another atom. In the case of primary amine, this vacant space gets filled by attaching itself to a nitrogen atom of the ammonia group, which leads to the formation of primary amines. In the case of Aryls, an aryl group always contains a ring.

Aryl group is categorized as simple aromatic compounds where one hydrogen atoms are removed from its group and leaving the position vacant for attachment with another atom. This vacant space is filled in this case with the ammonia group leading to the formation of primary amines.

While naming primary amines, their alkyls or aryl groups are mentioned as a prefix. As if a methyl group is present in primary amine. The compound is named as methylamine. But, if amine contains more functional groups in their structure, their substituent name is given to them. As for the amine group, the substituent name is “amino.”

Amines act as bases with litmus test due to the presence of lone pairs in one of their nitrogen atoms that are donated to protons. The process occurs when amine reacts with water; they form OH ions by donating their lone pair to hydrogen atom of H2O. As bases are the compounds that release OH ions, amines act as bases by following the same path.

The basicity of amines is observed by checking the stability of the compound formed after the donation of lone pairs. When the lone pair is donated by primary amines, the nitrogen atoms gets a positive charge. The positive charge is reduced while withdrawing the electrons towards them. Since there is only one alkyl group in primary amines, they act less basic than secondary amines.

What are Tertiary Amines?

Tertiary amines are the amines that contain three alkyls or aryl groups attached to a nitrogen atom in their structure. These amines are formed by the replacement of all three hydrogen atoms. Because they contain three hydrogen atoms bonded with the nitrogen atom, these are replaced by alkyl or aryl groups, thus leading to the formation of secondary amines. Therefore, no hydrogen atom remains in the structure of ammonia.

In the case of Aryls, an aryl group always contains a ring. The vacant spaces in aryls filled in this case with the ammonia group leading to the formation of tertiary amines. Nomenclature of tertiary amines differs as the three alkyl or aryl groups attached are needed to be mentioned in their name. For example, in the case of tributylamine, the nitrogen atoms are bonded to three butyl groups, which can be represented as (CH3CH2CH2CH2) 3N.

Tertiary amines act as basic but more basic than primary amines and ammonia but less basic than secondary amines; this is due to steric adherence as the three alkyl groups attached to one nitrogen atom. The alkyl groups are electron-donating. The nitrogen atom is reduced by electron-donating property of alkyls as they reduce nitrogen atoms.

Conclusion

Primary amines consist of one alkyl or aryl group, whereas, the tertiary amines are bonded with three alkyl or aryl groups. They are attached to the nitrogen atom with their structure.