The Rosenmund Reduction of Acid Chlorides to Aldehydes

Abstract

In the synthesis of complex molecules, particularly in connection with natural products, it is occasionally desirable to prepare an aldehyde when the readily available starting material is the corresponding acid. The Rosenmund reduction is probably the most useful method for application to a large number of aldehdyes of varied types. The Rosenmund reduction consists in the selective hydrogenation of an acid chloride in the presence of a suitable catalyst, usually supported palladium to the corresponding aldehyde.

Palladium oxide nanoparticles supported on graphene oxide: A convenient heterogeneous catalyst for reduction of various carbonyl compounds using triethylsilane

“…Very different methods also investigated the complete reductive conversion of a carbonyl group to a methylene group. Complete removal of oxygen‐containing groups or deoxygenation can be achieved by Wolff‐Kischner, Clemmensen, and Mozingo or thioketal reduction reactions . It should be noted that thioketal reduction is milder than either the Wolff‐Kishner or Clemmensen reduction reactions, which employ respectively strong basic or acidic conditions, that can affect other functional groups…”

“…Complete removal of oxygencontaining groups or deoxygenation can be achieved by Wolff-Kischner, [3][4][5] Clemmensen, [6,7] and Mozingo or thioketal reduction reactions. [8,9] It should be noted that thioketal reduction is milder than either the Wolff-Kishner or Clemmensen reduction reactions, which employ respectively strong basic or acidic conditions, that can affect other functional groups. [10] Trialkylsilanes are known to be poor/mild reducing agents, [11,12] even though reduction of carbonyl compounds with hydrosilanes in presence of Lewis or Brønsted acids is well-known.…”

Pyrethroid insecticides. Chapter III: Synthesis of 3-phenoxy mandelonitrile

“…or by reduction of the carboxylic acid 4e that has been achieved among others through the corresponding benzoyl chloride 4j using usually the Rosenmund reaction. 206 The direct oxidation of 3-phenoxytoluene (4b) using dioxygen as oxidant and cobalt diacetate as catalyst [Co(OAc)2/O2] has been reported in the patent literature (see references quoted in refs 178, 207 ) to provide 3phenoxybenzaldehyde (4a) (29% yield), the corresponding benzyl alcohol (4c) or its acetate 4cAc (21% yield) beside a large amount of by-products (21-50%). 207 Scheme 57.…”

Hydrogen

“…113, 114 The reduction is facile and the resulting aldehydes are susceptible to hydrogenation, therefore catalysts with attenuated reactivity, usually Pd on barium sulfate 113 or in some cases Pd/C, are employed. 115, 116 Platinum oxide, which has been deactivated using thiourea, is also a useful catalyst for this reaction.…”