page_title: Leuckart reaction
section_title: Mechanism
hierarchical_section_title: Leuckart reaction / Mechanism
caption_attribution_description: English: Leuchart reaction mechanism diagram
context_page_description: The Leuckart reaction is the chemical reaction that converts aldehydes or ketones to amines by reductive amination in the presence of heat. The reaction, named after Rudolf Leuckart, uses either ammonium formate or formamide as the nitrogen donor and reducing agent. It requires high temperatures, usually between 120 and 130 °C; for the formamide variant, the temperature can be greater than 165 °C.
context_section_description: Ammonium formate as reagent:
  Ammonium formate first dissociates into formic acid and ammonia. Ammonia then performs a nucleophilic attack on the carbonyl carbon.  The oxygen deprotonates hydrogen from nitrogen to form a hydroxyl.  The hydroxyl is protonated using hydrogen from formic acid, which allows for water molecule to leave.  This forms a carbocation, which is resonance stabilized. The compound attacks hydrogen from the deprotonated formic acid from previous step, forming a carbon dioxide and an amine.
  Formamide as reagent:
  Formamide first nucleophilically attacks the carbonyl carbon.  The oxygen is protonated by abstracting hydrogen from the nitrogen atom, subsequently forming a water molecule that leaves, forming N-formyl derivative, which is resonance stabilized.   Water hydrolyzes formamide to give ammonium formate, which acts as a reducing agent and adds on to the N-formyl derivative. Hydride shift occurs, resulting in loss of carbon dioxide.  Ammonium ion is added forming an imine and releasing ammonia. The imine goes through hydrolysis to form the amine, which is depicted in the scheme below.
caption: The mechanism depicts the conversion of ketone (or aldehyde) to an amine using ammonium formate as a reagent.
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