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

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

“…Castor oil hydrogenation occurred only when the oil was added to the Pd/C catalyst before the limonene; when the oil was added to the catalyst after the limonene, the castor oil was recovered unreacted and only limonene disproportionation products were identified (23). These results suggest that when limonene was added to the catalyst before the castor oil, the active sites of the catalyst became unavailable because they were blocked by the limonene disproportionation reactions, and the double bonds of the castor oil could not reach the sites because of steric hindrance and/or diffusion effects.…”

“…The reaction parameters studied were: concentration of Pd/C catalyst (0.1, 0.25, 0.5, 0.75, 1.0, and 2.0% of Pd/mol double bonds); reaction temperature (160, 170, and 178°C); castor oil/limonene ratio (1:3 molar ratio); and reaction time (0.5, 1, 2, and 3 h). The reaction of Pd/C and limonene was studied previously (23), and the limonene disproportionation products were characterized. The reaction of Pd/C and castor oil only was performed using the same reaction parameters of temperature, time, and percentage of Pd/C.…”

Kinetics of Limonene Hydrogenation in High-Pressure CO2 at Variation of Hydrogen Pressure

“…The limonene isomerization products such as terpinolene and γ-terpinene were detected also. The presence of p -menth-3-ene in the product of the catalytic hydrogenation of limonene was reported in ref . Hydrogenation of terpenes in high-pressure CO 2 exhibits some advantages in comparison with the reaction in the liquid phase in the absence of CO 2 …”

Sustainable Materials and Biorefinery Chemicals from Agriwastes

“…From Table 3 it may be observed that the intermediate isomerisation product α-terpinene was only found for SIRAL 20 and at a very low level (4%) and 100% conversion of limonene to p-cymene was achieved with Siral 40 after 10 min. The speed of the reaction when heated by microwave irradiation is possibly the reason for the high selectivities, since the short reaction time necessary to attain these high conversions and selectivity to pcymene avoid the formation of undesirable by-products such as mentanes (products of disproportionation) or polymers, that are found with the longer reaction times employed with conventional heating [18]. Thus, microwave irradiation favoured the production of pcymene from limonene, avoided the use of highly toxic benzene, toluene and aluminium trichloride and allowed high conversions and excellent selectivities towards the desired product due to the accelerated reaction rates.…”