Castor oil hydrogenation by a catalytic hydrogen transfer system using limonene as hydrogen donor

The hydrogenation of castor oil was investigated using a catalytic transfer hydrogenation system in which palladium on carbon was the catalyst and limonene was the solvent and hydrogen donor. The highest percentage of castor oil modification occurred at 178°C using 1% Pd/C and an oil/limonene ratio of 1∶3. The optimized system presented very good reproducibility and 100% conversion of the ricinoleate. GC using a mass spectrometer as detector and 1H NMR spectra of the products indicated that hydrogenation was accompanied by dehydrogenation leading to a mixture of 12‐hydroxy and 12‐keto stearic derivatives.