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 degrees 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 H-1 NMR spectra of the products indicated that hydrogenation was accompanied by dehydrogenation leading to a mixture of 12-hydroxy and 12-keto stearic derivatives.