page_title: Arndt–Eistert reaction
section_title: Conditions
hierarchical_section_title: Arndt–Eistert reaction / Conditions
caption_attribution_description: English: Arndt-Eistert reaction with ketene intermediate
context_page_description: In organic chemistry, the Arndt–Eistert reaction is the conversion of a carboxylic acid to its homologue. Named for the German chemists Fritz Arndt and Bernd Eistert, the method entails treating an acid chlorides with diazomethane. It is a popular method of producing β-amino acids from α-amino acids.
context_section_description: Aside from the acid chloride substrate, three reagents are required: diazomethane, water, and a metal catalyst.  Each has been well investigated.
  The diazomethane is required in excess so as to react with the HCl formed previously.   Not taking diazomethane in excess results in HCl reacting with the diazoketone to form chloromethyl ketone and N₂. Mild conditions allow this reaction to take place while not affecting complex or reducible groups in the reactant-acid.
  The reaction requires the presence of a nucleophile (water).  A metal catalyst is required.  Usually Ag₂O is chosen but other metals and even light effect the reaction.
caption: Arndt-Eistert reaction with ketene intermediate.
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