نتایج جستجو برای: hydrogenation
تعداد نتایج: 8711 فیلتر نتایج به سال:
A series of ruthenium catalysts supported on two different carbons were tested for the hydrogenation of lactic acid to 1,2-propanediol and butanone to 2-butanol. The properties of the carbon supports were investigated by inelastic neutron scattering and correlated with the properties of the ruthenium deposited onto the carbons by wet impregnation or sol-immobilisation. It was noted that the rat...
Self-metathesis of undecenoic acid with [(PCy3)2Cl2Ru=CHPh] (2), followed by exhaustive hydrogenation yielded pure 1,20-eicosanedioic acid (5) (>99%) free of side-products from isomerization. Polycondensation with eicosane-1,20-diol (6), formed by reduction of the diol, yielded polyester 20,20 (Tm = 108 °C). By comparison, the known ADMET polymerization of undec-10-enyl undec-10-enoate (7), and...
The development of transition-metal-catalyzed asymmetric hydrogenation could be stated as the cradle of modern enantioselective catalysis. Since the early asymmetric hydrogenation example from Knowles and Sabacky in 1968, the method has rapidly advanced over the years into an important tool in academia and chemical industry. In general, for these transformations the development of effective tra...
Hydrogenation of unsaturated hydrocarbon compounds catalyzed by transition metals is traditionally believed to be a structure-insensitive reaction. However, recent progress in understanding the microscopic details of this process challenges the universality of this common belief. Recently, several examples of catalytic systems were described in the literature where hydrogenation of the olefinic...
The hydrogenation of monatomic silicene sheet on Ag(111) was studied by scanning tunneling microscopy and density functional theory calculations. It was observed that hydrogenation of silicene at room temperature results in a perfectly ordered γ-(3×3) superstructure. A theoretical model, which involves seven H atoms and rearranged buckling of Si atoms, was proposed and agrees with experiments v...
Soybean lecithin containing a mixture of phospholipids (PLs) is an important co product obtained during soybean oil refining. Saturated rich PLs find several applications in food, cosmetic and pharmaceutical areas. The present study reports a simple, rapid, efficient and continuous hydrogenation process using 10% Pd/C catalyst at various temperatures and pressures. Degree of hydrogenation was m...
The mechanism of CO hydrogenation to CH4 at 260 °C on a cobalt catalyst is investigated using steady-state isotopic transient kinetic analysis (SSITKA) and backward and forward chemical transient kinetic analysis (CTKA). The dependence of CH x residence time is determined by 12CO/H2 → 13CO/H2 SSITKA as a function of the CO and H2 partial pressure and shows that the CH4 formation rate is mainly ...
Hydrogenation of six model feeds containing three-, two-, and one-ring aromatic compounds was investigated to gain insights into the aromatic hydrogenation reaction chemistry over a commercial NiMo catalyst under practical reaction conditions. The hydrogenation reactivity of the aromatic compounds followed the following order: phenanthrene ∼ two-ring aromatics . one-ring aromatic. Comparison wi...
A variety of 3-substituted benzisoxazoles were reduced with hydrogen using the chiral ruthenium catalyst, {RuCl(p-cymene)[(R,R)-(S,S)-PhTRAP]}Cl. The ruthenium-catalyzed hydrogenation proceeded in high yield in the presence of an acylating agent, affording α-substituted o-hydroxybenzylamines with up to 57% ee. In the catalytic transformation, the N-O bond of the benzisoxazole substrate is reduc...
It is highly desirable to produce narrow-width graphene nanoribbons (GNRs) with smooth edges in large scale. In an attempt to solve this difficult problem, we examined the hydrogenation of GNRs on the basis of first principles density functional calculations. Our study shows that narrow GNRs can be readily obtained from wide GNRs by partial hydrogenation. The hydrogenation of GNRs starts from t...
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