Highly Selective and Multigram Hydrogenation of Citral into Citronellal by Palladium Nanoparticles in Water

The synthesis of citronellal, an added-value chemical for perfumery, was performed through selective and green hydrogenation citral into citronellal in water. Aqueous suspensions spherical ammonium-capped palladium nanoparticles with sizes around 3 nm selectively reduced the conjugated carbon–carbon double bond. An excellent selectivity up to 97% achieved at complete conversion presence potassium hydroxide proved crucial control avoid other coproducts. These optimized conditions were further applied a 135 g substrate loading, affording relevant turnover number (TON) 10,000.