Synthesis and Reactions of Quinoline
Synthesis and Reactions of Quinoline
Quinoline consists of a benzene ring fused to the α, β positions of a pyridine ring. Its name derived from the fact that it was first obtained by heating the famous antimalarial alkaloid 'quinine', with alkali. Quinoline occurs in coal-tar, bone oil, and in angostura bark.
Synthesis of Quinoline
Skraup Synthesis of Quinoline
A mixture of aniline and glycerol is heated in the presence of sulphuric acid and a mild oxidizing agent (nitrobenzene or arsenic pentoxide), Quinoline is obtained.
Friedlander Synthesis of Quinoline
The condensation of o-Aminobenzaldehyde with acetaldehyde in the presence of an alkali gives Quinoline.
Physical Properties of Quinoline
Quinoline is a colorless liquid, Its boiling Point is 237°C, turns yellow on standing, and has pyridine-like smell. Quinoline is miscible with most organic solvents, and dissolves in water to about 0-7 % at room temperature.
Chemical Properties of Quinoline/Reactions of Quinoline
Resonance in Quinoline
Basic Character of Quinoline
Quinoline is a slightly weaker base than pyridine and reacts with acids to yield salts which are sparingly soluble in water.
Electrophilic Substitution Reactions in Quinoline
Quinoline undergoes electrophilic substitution reactions only under vigorous conditions. Electophile entroduce at C-5 and C-8 position of quinoline.
Nitration of Quinoline
Quinoline undergoes nitration with fuming nitric acid and sulphuric acid to give a mixture of 8-nitroquinoline and 5-nitroquinoline.
Sulphonation of Quinoline
Quinoline is sulphonated with fuming sulphuric acid at 220°C to give a mixture of quinoline-8-sulphonic acid and quinoline-5-sulphonic acid.
Nucleophilic Substitution Reactions in Quinoline
Quinoline undergoes nucleophilic substitution reactions. Substitution occurs at C-2 and C-4 whenC-2 is blocked.
Reaction of Quinoline with Sodamide
Quinoline reacts with sodamide in liquid ammonia at about 100°C to form 2-Aminoquinoline.
Reaction of Quinoline with Potassium Hydroxide
Quinoline reacts with KOH at 220°C gives 2-hydroxyquinoline.
Reaction of Quinoline with n-Butyl Lithium
Quinoline reacts with n-butyllithium at 100°C to give 2-n-butylquinoline.
Reaction of Quinoline with Alkyl halide
Quinoline reacts with alkyl halides to form N-alkylquinolium halides.
Reduction of Quinoline
Quinoline undergoes reduction with H
2-Pt to form decaquinoline while with Sn/HCl reduced to 1,2,3,4-trtrahydroquinoline.
Oxidation of Quinoline
Quinoline may be oxidized by peracitic acid to give quinoline-N-oxide and with alkaline KMnO
4 yields pyridine-2,3-dicarboxylic acid.
