Rosenmund reaction, avoidance

As catalyst for the Rosenmund reaction palladium on a support, e.g. palladium on barium sulfate, is most often used. The palladium has to be made less active in order to avoid further reduction of the aldehyde to the corresponding alcohol. Such a poisoned catalyst is obtained for example by the addition of quinoline and sulfur. Recent reports state that the reactivity of the catalyst is determined by the morphology of the palladium surface." ... 

Reduction of acids to aldehydes one step from the acid, how to avoid the Rosenmund reaction or the reduction to alcohol followed by oxidation Aldehydes are very important reagent for fine organics, the access to those compounds is always multistep. Development of a catalyst for the reduction of an acid function to the aldehyde without reduction of a double bond in the framework of the molecule will be presented and discussed. 

A number of side-reactions may be observed with the Rosenmund reduction, which however can be avoided by proper reaction conditions. A poorly deactivated catalyst will lead to reduction of aldehyde 2 to the alcohol 4, or even to... 

Acid chlorides can be reduced to aldehydes either by catalytic hydrogenation or by reaction with a metal hydride. In both cases, the reagent and the reaction conditions are selected to avoid the further reduction of the aldehyde. The conversion of an acid chloride to an aldehyde can be carried out by the Rosenmund reduction, which uses hydrogen gas and a modified palladium catalyst. The palladium catalyst is altered to prevent further reduction of the aldehyde. To prepare the catalyst, the palladium is treated with quinoline, an aromatic heterocyclic amine, and is heated with sulfhr. 

---

See also in sourсe #XX -- [ , ]

---