Citation:

Polshettiwar, V. AND R. S. VARMA. Ruthenium hydroxide supported on magnetic nanoparticles: a benign aqueous protocol for hydration of nitriles . Protocol Exchange. Nature Publishing Group, New York, NY, Protocols(565):9 pp, (2009).

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To inform the public.

Description:

Amides are an important class of compounds in the chemical and pharmaceutical industry1,2. Conventionally, amides have been synthesized by the hydration of nitriles, catalyzed by strong acids3 and bases4. Many by-products such as carboxylic acids are produced due to hydrolysis of the starting nitriles and amides under these conditions. Also, several sensitive functional groups do not tolerate such harsh conditions, which results in a decrease in the selectivity of the reaction protocol. Numerous processes using homogeneous metal complexes have been reported for this hydration protocol5. However, these suffer from various drawbacks, such as difficulty in separation of product and catalyst from the reaction mixture, as well as the use of inert atmosphere for handling air-sensitive metal catalysts. Heterogeneous systems have been reported, such as alumina6, potassium fluoride-doped Al2O37 and phosphates8, silica-supported manganese oxides9, modified hydroxyapatite10, and ruthenium hydroxide coated on alumina and ferrites11. However, turnover numbers of these protocols are still small and reusability of the catalyst is intricate. A recently developed hydration protocol in pure water is good in terms of reaction conditions and product yield12, but it still needs traditional work-up using toxic organic solvents to isolate the product and uses expensive ruthenium complexes as catalysts. Magnetic nanoparticles have emerged as a robust, high surface area heterogeneous catalyst support13. Magnetic recoverability, which eliminates the necessity of catalyst filtration after completion of the reaction, is an additional attribute of these materials. In a recent publication, we reported a simple and efficient synthesis of nano-ferrite-supported, magnetically recyclable ruthenium hydroxide [Ru(OH)x] catalyst and its application in hydration of nitriles in benign aqueous medium14

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