Self-metathesis Of Methyl Oleate Research Articles

Self-Metathesis of Methyl Oleate Using Ru-NHC Complexes: A Kinetic Study

A kinetic study concerning the self-metathesis of methyl oleate and methyl elaidate was performed, using a variety of NHC-ruthenium pre-catalysts, bearing either mesityl groups or di-isopropyl-phenyl groups on the NHC ligand and various trans ligands with respect to the NHC unit. We showed that the system can be satisfactorily described using one initiation constant per pre-catalyst and four propagation constants that, conversely, do not depend on the pre-catalyst. The difference of reactivity with oleate (Z) and elaidate (E) can be fully explained by the propagation parameters; the studied pre-catalysts initiate with the same rate starting from the Z or the E olefin. The ranking of the propagation parameters is driven by the thermodynamic equilibrium. The transformation rates of Z and E isomers is only driven by these propagation constants and nothing differentiates the initiation step.

Valorisation of plant oil derivatives via metathesis reactions: Study of the cross-metathesis of methyl oleate with cinnamaldehyde

The cross-metathesis of methyl oleate (MO) with cinnamaldehyde (CA) to yield 2-undecenal, methyl 11-oxo-9-undecenoate, methyl 10-phenyl-9-decenoate and 1-decenylbenzene was investigated using the second-generation Hoveyda-Grubbs Ru complex (HG2). Self-metathesis of methyl oleate was the main undesired secondary reaction. The reaction was carried out at 323 K using reactant molar ratios (RCA/MO) between 1 and 20. The yield (YC-M) and selectivity (SC-M) to cross-metathesis products increased with RCA/MO until reaching both parameters 100% for RCA/MO = 20. The effect of temperature on catalyst activity and selectivity was investigated in the 303–363 K range; YC-M increased significantly with temperature at the expense of the formation of MO self-metathesis products. No significant HG2 deactivation was observed after performing three consecutive catalytic tests of MO/CA cross-metathesis at 323 K.

Ru complexes of Hoveyda-Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions.

Hoveyda–Grubbs type catalysts with cationic tags on NHC ligands were linker-free immobilized on the surface of lamellar zeolitic supports (MCM-22, MCM-56, MCM-36) and on mesoporous molecular sieves SBA-15. The activity of prepared hybrid catalysts was tested in olefin metathesis reactions: the activity in ring-closing metathesis of citronellene and N,N-diallyltrifluoroacetamide decreased in the order of support MCM-22 ≈ MCM-56 > SBA-15 > MCM-36; the hybrid catalyst based on SBA-15 was found the most active in self-metathesis of methyl oleate. All catalysts were reusable and exhibited low Ru leaching (<1% of Ru content). XPS analysis revealed that during immobilization ion exchange between Hoveyda–Grubbs type catalyst and zeolitic support occurred in the case of Cl− counter anion; in contrast, PF6− counter anion underwent partial decomposition.

Valorisation of vegetable oils via metathesis reactions on solid catalysts: Cross-metathesis of methyl oleate with 1-hexene

The activity and selectivity of silica-supported Hoveyda–Grubbs (HG) complex for the cross-metathesis of methyl oleate with 1-hexene to obtain 1-decene, methyl 9-tetradecenoate, 5-tetradecene and methyl 9-decenoate were studied in a batch reactor. The HG complex loading was varied between 0.87 and 11.6wt%. Competitive secondary reactions were the self-metathesis of methyl oleate and the self-metathesis of 1-hexene. The yield to cross-metathesis products (ηC-M) was 47% when a 1-hexene/methyl oleate reactant ratio (RC6/MO) of one was employed. The ηC-M value increased with increasing 1-hexene initial concentration, reaching 87% for RC6/MO=7. The selectivity to terminal olefins also increased at the expense of internal olefins among the cross-metathesis products when the concentration of 1-hexene was increased.

Metathesis of renewable raw materials—influence of ligands in the indenylidene type catalysts on self-metathesis of methyl oleate and cross-metathesis of methyl oleate with (Z)-2-butene-1,4-diol diacetate

The influence of different N-heterocyclic carbene (NHC) and other neutral ligands on the outcome of the cross-metathesis reaction of methyl oleate with (Z)-2-butene-1,4-diol diacetate and self-metathesis of methyl oleate was studied for a series of indenylidene type Ru catalysts.

Self-metathesis of methyl oleate on silica-supported Hoveyda–Grubbs catalysts

The self-metathesis of methyl oleate (MO) to yield 9-octadecene and 9-octadecene-1,18-dioate (9-OD) was studied in liquid-phase on silica-supported Hoveyda–Grubbs complex catalysts (HG/SiO2) containing 0.43–6.0wt.% HG. The reaction was carried out in a batch reactor at 303–343K and 101.3kPa, using cyclohexane as solvent. HG/SiO2 catalysts were active and highly selective for the MO metathesis reaction; equilibrium values of MO conversion and 9-OD yield were reached in 80min. No catalyst leaching took place in cyclohexane. Catalysts containing HG >0.87wt.% showed no significant deactivation after two consecutive catalytic tests.

Linker‐Free, Silica‐Bound Olefin‐Metathesis Catalysts: Applications in Heterogeneous Catalysis

A set of heterogenized olefin-metathesis catalysts, which consisted of Ru complexes with the H(2)ITap ligand (1,3-bis(2',6'-dimethyl-4'dimethyl aminophenyl)-4,5-dihydroimidazol-2-ylidene) that had been adsorbed onto a silica support, has been prepared. These complexes showed strong binding to the solid support without the need for tethering groups on the complex or functionalized silica. The catalysts were tested in the ring-opening-ring-closing-metathesis (RO-RCM) of cyclooctene (COE) and the self-metathesis of methyl oleate under continuous-flow conditions. The best complexes showed a TON>4000, which surpasses the previously reported materials that were either based on the Grubbs-Hoveyda II complex on silica or on the classical heterogeneous Re(2)O(7)/B(2)O(3) catalyst.

Metathesis of Fatty Acid Ester Derivatives in 1,1-Dialkyl and 1,2,3-Trialkyl Imidazolium Type Ionic Liquids

The self-metathesis of methyl oleate and methyl ricinoleate was carried out in the presence of ruthenium alkylidene catalysts 1–4 in [bmim] and [bdmim][X] type ionic liquids (RTILs) (X = PF6−, BF4− and NTf2−) using the gas chromatographic technique. Best catalytic performance was obtained in [bdmim][X] type ionic liquids when compared with [bmim][X] type ionic liquids. Catalyst recycling studies were also carried out in the room temperature ionic liquids (RTILs) with catalysts 1–4 in order to explore their possible industrial application.

Continuous flow homogeneous alkene metathesis with built-in catalyst separation

Continuous flow homogeneous alkene metathesis using a supported ionic liquid phase (SILP) catalyst with CO2 as a transport vector allows the self-metathesis of methyl oleate with only a slight loss of activity for at least 10 h; cross-metathesis of dimethyl maleate with methyl oleate ceases after 3 h, but the catalyst remains active for methyl oleate metathesis. The reasons for this unusual behaviour are explored and a practical system for the cross-metathesis of methyl oleate with dimethyl maleate, under batch conditions, is described.

Metathesis of Unsaturated Fatty Acid Esters with a Reusable Ruthenium Catalyst

Metathesis of unsaturated fatty acid esters with a magnetic nanoparticle-supported Hoveyda-Grubbs catalyst 1 was described. Thus, self-metathesis of methyl oleate (2) was ­carried out in the presence of the immobilized Grubbs II catalyst 1 grafted onto magnetic nanoparticles (100 nm, matrix with starch) [2/1 (mol/mol) = 2008] to give dimethyl-9-octadecene-1,18-dioate (3) in 73% yield with 489 h-¹ TOF. Cross-metathesis of methyl oleate (2) and methyl acrylate (5) with 1 [2/1 (mol/mol) = 497] gave dimethyl undec-2-en-1,11-dioate (6) in 60% yield with 12 h-¹ TOF. Self-metathesis of a macro-monomer 8 using 1 [8/1 (mol/mol) = 98] ­afforded a polymer 9 in 90% yield with 29 h-¹ TOF.