Determination of the disproportionation products of limonene used for the catalytic hydrogenation of castor oil

The direct determination by GC–MS analysis of the products from the limonene disproportionation obtained from the catalytic hydrogenation of castor oil is not possible since a transesterification of the oil is required before injection. Therefore, a method for the determination of those products is proposed here: a solid-phase microextraction (SPME) followed by GC–MS. With the optimization of SPME it was possible to isolate a great number of products of the disproportionation of limonene used as hydrogen donor in the catalytic hydrogenation of castor oil by Pd/C. This system also proved to be appropriate to monitor castor oil hydrogenation by following and identifying the limonene disproportionated products.