Question

Arrange these compounds in order of increasing boiling point. List the compound with the lowest boiling point first. Which of these compounds is most basic? Arrange these anions in order of increasing nucleophilicity. Use the least nucleophilic anion first.

Answer 1

1) The boiling point depends upon the extent of intermolecular forces between the molecules. Here the compound 2 contains two hdyroxyl groups so will be most strongly bonded due to greatest extent of hydrogen bonds. While compound 1 has one hydroxyl group. so it will have hydrogen bond but less as compared to compound 2. so it will have less boiling point than compound 2.

However the compound 3 will have least boiling point as it lacks any hydrogen bond (absence of OH group)

Order will be 3<1<2 .

2) A) pyrrole: the lone pair of nitrogen ( which is responsible for base strength) is involved in the armaticity of pyrrole so it is not available ( least basic)

D) Aniline: due to delocalization of the nitrogen non-bonding electron pair into the aromatic ring , aniline is a weak base

C) The lone pair of pyridine is comparitively available so it will be more basic as compared to above compounds

B) the given secondary amine is most basic due to complete availability of lone pair of electrons

3) the nucelophile should be able to share is electron easily.

Ion 1) due to highly electronegative elements ( they pull electrons towards them) the negative charge on oxygen gets diminished .( least nucleophilic)

Ion 3) due to delocalization of electron again less nucleophilic

Ion 2) most nucleophilic

Order 1< 3 <2