CHAPTER 18: Unit 3. Amines and Amides Physical Properties

Amines and Amides Physical Properties

Primary and secondary amines can form hydrogen bonding due the fact that they have the bonding N-H. Primary and secondary amines can form hydrogen bonding within themselves (intermolecular forces) as well as with polar water (intermolecular forces). Amines have strong “fishy” smell.

Reference: https://socratic.org/questions/54875486581e2a7a137fcf69

Reference: https://chem-guide.blogspot.com/2010/04/physical-properties-of-aliphatic-amines.html

Primary amines have more hydrogen bonding within themselves and with water. The melting and boiling points therefore are higher of primary amines compared with secondary amines. Secondary amines have more hydrogen bonding than tertiary amines and therefore secondary amines have higher melting and boiling points than tertiary amines. Tertiary amines can form hydrogen bonding only through their nitrogen atom only. They are missing a hydrogen atom that the secondary amines do have.The solubility of amines in water will depend on the number of carbon atoms in the hydrocarbon chain. Amines with five carbon atoms are soluble in water. Amines above six carbon atoms are not soluble. The higher the chain (chain of five carbon atoms) the lower the solubility of amines in water.

The video below illustrates the boiling points of amines:

The following figure exhibits boiling points of amines:

Reference: https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Amines/Properties_of_Amines/Basic_Properties_of_Amines

Some physical properties of some Amides: Reference: https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Amides/Properties_of_Amides/Physical_Properties_of_Carboxylic_Acid_Derivatives

Other organic derivates of Amines and their boiling as well melting points are given below: Reference: https://chemistry.gsu.edu/files/2014/11/Amines.pdf

Some physical Properties of Amides are shown below:

Reference: https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_The_Basics_of_GOB_Chemistry_(Ball_et_al.)/15%3A_Organic_Acids_and_Bases_and_Some_of_Their_Derivatives/15.14%3A_Physical_Properties_of_Amides

The video below illustrates the physical properties of amides:

Amides are less soluble than amines (less hydrogen bonding). Amides higher in the carboxylic acids chain are not soluble. Amides are less soluble in water compared with their corresponding carboxylic acids which had contribution to their formation.

The higher the molar mass of the amides, the higher the boiling points.