Medicinal Chemistry

Synthesis of phenytoin from benzil and urea

BACKGROUND Principle: Base catalyzed reaction between benzyl and urea is used for synthesis of phenytoin. The reaction is proceeding via intramolecular cyclization to form an intermediate heterocylic pinacol, which on acidification yield hydantoin (phenytoin) as a result of 1,2-diphenyl shift in pinacol rearrangement reaction.1 Aim: To prepare phenytoin from benzil and urea. Reaction: Mechanism: Use:  … Read more

Synthesis of sulphanilamide from acetanilide

BACKGROUND Principle: Sulphanilamide can beprepared by taking acetanilide and treating it with excess of chlorosulphonic acid, which gives p-acetamidobenzenesulphonyl chloride which readily converted into corresponding p-acetamidobenzenesulphonamides upon reaction with ammonia or ammonium carbonate. The acetamido groups can easily undergo acid catalyzed hydrolysis reaction to form p-aminobenzene sulphonamide (sulphanilamide).1 Aim: To prepare sulphanilamide from acetanilide. Reactions: … Read more

Synthesis of p-nitroaniline from acetanilide

BACKGROUND Principle: Here in first step electrophilic aromatic substitution (nitration) of nitronium ion is occurring towords para position of acetanilide more than ortho position due to steric reasons. Nitronium ion is the electrophile generates from fuming nitric acid in presence of fuming sulphuric acid. In the second step p-nitroaniline is prepared from p-nitro acetanilide due … Read more

Synthesis of paracetamol from p-aminophenol

 BACKGROUND Principle: The synthesis of the amide essentially just requires running the reaction under certain temperature conditions with an appropriate catalyst. Paracetamol is prepared from p- aminophenol by acetylating it with acetic anhydride in the presence of 3-4 drops of concentrated sulphuric acid as catalyst.1 Aim: To prepare paracetamol from p-aminophenol. Reaction: Mechanism: Uses: … Read more

Synthesis of p-aminophenol from nitrobenzene

BACKGROUND Principle: In the first step catalytic reduction of nitrobenzene is occurring forming N-phenylhydroxylamine in presence of zinc and ammonium chloride with sufficient water. In the second step rearrangement is occurring which involves the conversion of an N- phenylhydroxylamine into the corresponding 4-aminophenol through treatment with an aqueous mineral acid such as sulfuric acid (Bamberger … Read more

Synthesis of m-nitrophenol from nitrobenzene

BACKGROUND Principle: In the first step nitrobenzene converts to m-dinitrobenzene due to electrophilic aromatic substitution in presence of nitrating reagents. It is a slow process and more difficult to add the second NO2+ because the nitro substitutent is a powerful deactivator. Since NO2 is a meta director, the resultant dinitrobenzene is almost exclusively 1,3-dinitrobenzene. In … Read more

Synthesis of methyl salicylate

BACKGROUND Principle: Methyl salicylate (oil of wintergreen) is an organic ester. When an acid (containing the –COOH group) reacts with an alcohol (a compound containing an –OH group) formed an ester. The type of reaction may be known as condensation reaction because the small molecule of H2O is eliminated from the reactants while the remaining … Read more

Synthesis of methyl orange from sulphanilic acid

BACKGROUND Principle: Sulphanilic acid with sodium carbonate converted into sodium salt of p-aminobenzene sulphonate, It undergoes diazotization reaction in presence of nitrous acid to form diazonium chloride salt. The diazonium chloride then ionizes in aquous solution giving sodium ion, chloride ion and the internal salt (–O3SC6H4N2+). N, N-dimethylaniline hydrochloride added to the internal salt, coupling … Read more

Synthesis of fluorescein from resorcinol and phthalic anhydride

BACKGROUND Principle: Here a modified Friedel-crafts acylation reaction is occurring. This reaction is a series of electrophilic aromatic substitutions, with hydroxyl leaving groups picking up protons by Lewis acid catalysis. It increases the electrophilicity of pthalic anhydride in the first step, and facilitates the elimination of the hydroxyl groups. In order to get the form … Read more