Model
Digital Document
Publisher
Florida Atlantic University
Description
The acid-catalyzed N-alkylation of an amide by an alcohol or an alkene
occurs successfully if the intermediate carbenium ion is highly stabilized
and therefore readily formed. This is because carbenium ion formation
must compete successfully with protonation and consequent deactivation
of the amide. The carbenium ion will N-alkylate the amide unless steric
requirements preclude such attack. In boiling glacial acetic acid acetamide is N-alkylated readily by ferrocenylmethanol, a-hydroxyethylferrocene and vinylferrocene but slowly by triphenylmethanol. Triphenylnmethylation is accelerated by a small amount of sulfuric acid. Reaction
of acetamide with diphenylmethanol in boiling glacial acetic acid yields
N-diphenylmethylacetamide in the presence of sulfuric acid, diphenylmethyl acetate in the ascence of sulfuric acid. Under both these conditions
the reaction of acetamide with benzyl alcohol fails, benzyl acetate
being the sole product. Nicotinamide is triphenylmethylated and ferrocenylmethylated only on the amide nitrogen, not on the pyridine nitrogen.
N-methylacetamide, a secondary amide, can be N-ferrocenylmethylated.
occurs successfully if the intermediate carbenium ion is highly stabilized
and therefore readily formed. This is because carbenium ion formation
must compete successfully with protonation and consequent deactivation
of the amide. The carbenium ion will N-alkylate the amide unless steric
requirements preclude such attack. In boiling glacial acetic acid acetamide is N-alkylated readily by ferrocenylmethanol, a-hydroxyethylferrocene and vinylferrocene but slowly by triphenylmethanol. Triphenylnmethylation is accelerated by a small amount of sulfuric acid. Reaction
of acetamide with diphenylmethanol in boiling glacial acetic acid yields
N-diphenylmethylacetamide in the presence of sulfuric acid, diphenylmethyl acetate in the ascence of sulfuric acid. Under both these conditions
the reaction of acetamide with benzyl alcohol fails, benzyl acetate
being the sole product. Nicotinamide is triphenylmethylated and ferrocenylmethylated only on the amide nitrogen, not on the pyridine nitrogen.
N-methylacetamide, a secondary amide, can be N-ferrocenylmethylated.
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