Question

organic chemistry

Question 22: Arrange the following compounds in order of decreasing boiling point and explain your ranking: (1=highest b.p./4=lowest b.p.) All have similar molar masses NH: NH2 H2N

Answer 1

This is the Rank of all the Ammine Compounds. The Decreasing order of boiling point is 1>2>3>4.

The Reason behind this sequence is Hydrogen Bonding. Propylenediamine has 2 -NH_{​​​​2} groups and thus has the greatest extent of Hydrogen Bonding, and consequently the highest boiling point among these 4 amines.

Between butylamine and N,N-diethylamine, Butylamine has higher boiling point, because it has 2 Ha in N atom, whereas N, N-diethylamine has only 1H in N atom. Thus, Butylamine has a greater extent of Hydrogen Bonding and consequently Higher boiling point than N, N-diethylamine.

N,N,N-diethylmethylamine has the lowest boiling point, because it has no H, attached to N atom, and thus can't undergo any Hydrogen Bonding, and consequently has the lowest boiling point.