The Bucherer reaction in organic chemistry is the reversible conversion of a naphthol to a naphthylamine in the presence of ammonia and sodium bisulfite
Rosenmund reaction is a hydrogenation process where molecular hydrogen reacts with the acyl chloride in the presence of catalyst – palladium on...
Bucherer Reaction
The Bucherer reaction in organic chemistry is the reversible conversion of a naphthol to a
naphthylamine in the presence of ammonia and sodium bisulfite
2C10H7-OH + NH3 ⇌ 2C10H7-NH2 + H2O
The German chemist Hans Theodor Bucherer (1869–1949) discovered (independent from Lepetit) its
reversibility. The organic reaction also goes by the name Bucherer-Lepetit reaction or (wrongly)
the Bucherer-Le Petit reaction.
Mechanism
In the first step of the reaction mechanism a proton adds to a carbon atom with high electron
density therefore by preference to C2 or C4 of naphthol (1). This leads to resonance stabilized
adducts 1a-1e
De-aromatization of the first ring of the naphthalene system occurs at the expense of 25 kcal/mol. In
the next step a bisulfite anion adds to C3 through 1e. This results in the formation of 3a which
tautomerizes to the more stable 3b to the sulfonic acid of tetralone. A nucleophilic addition follows
of the amine with formation of 4a and its tautomer 4b loses water to form the resonance stabilized
cation 5a. This compound is deprotonated to the imine 5b or the enamine 5c but an equilibrium
exists between both species. The enamine eliminates sodium bisulfite with formation of
naphthylamine 6.
, It is important to stress that this is a reversible reaction. The reaction is summarized as follows
The Bucherer carbazole synthesis is a related reaction
Rosenmund Reduction Mechanism
Rosenmund reaction is a hydrogenation process where molecular hydrogen reacts
with the acyl chloride in the presence of catalyst – palladium on barium sulfate.
Rosenmund Reduction
the Rosenmund reduction is a reaction where acid chlorides are converted into
aldehydes by employing hydrogen gas over palladium poisoned by barium sulfate.
An example of this catalytic hydrogenation of acyl chlorides forming aldehydes is
shown below.
Mechanism of Rosenmund Reduction
Step 1
Hydrogen gas (in the presence of the Rosenmund Catalyst) is passed through acyl
chloride, resulting in the formation of an aldehyde and hydrochloric acid
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