ConclusionsWe have shown that the hydrogenation reaction of renewablepolyunsaturated methyl esters of palm kernel and sunflower oilsto the saturated product methyl stearate (MS) using transitionmetal catalytic complexes modified with hydrolysis stable mon-odentate sulfonated triphenylphosphite ligands proceeds smoothlyin the absence or presence of organic solvents such as methanol.Much higher selectivities up to 95.8 mol% of the saturated C18:0ester were achieved with transition metal catalytic complexesmodified with sulfonated triphenylphosphite ligands comparedwith the selectivities obtained with their corresponding complexesmodified by conventional triphenylphosphite or triphenylphos-phine ligands. The bulkiness of the transition metal sulfonatedtriphenylphosphite catalytic system which is in the form of atriisooctylammonium salt could offer the possibility of the easyseparation of the catalyst from the reaction mixture by means of amembrane made from materials such as crosslinked polyolefins,poly(vinylidene fluoride), polyamides, etc. and this membranecatalyst separation technique has still to be developed. The hydro-genation reaction of the polyunsaturated C18 esters part of palmkernel oil and sunflower oil methyl esters toward the desired sat-urated product MS is an interesting catalytic reaction because itcould acts as a model reaction for studying the full hydrogenationof edible vegetable oil triglycerides to hardfats to be further sub-jected to interesterification reactions with liquid edible vegetableoils to yield foodstuffs with zero amounts of trans-fats and further-more because the saturated product MS could be used as a startingmaterial for the selective heterogeneous catalytic hydrogenolysisreaction of the C18:0 fatty ester to the corresponding saturatedC18:0 stearyl alcohol which is an important industrial fatty alco-hol. Hence, we are currently investigating the scope of this usefulhydrogenation reaction of renewable unsaturated methyl esters ofvegetable oils to yield methyl stearate employing transition metalcatalytic complexes modified with sulfonated phosphites.