592-43-8Relevant articles and documents
Strength of solid acids and acids in solution. Enhancement of acidity of centers on solid surfaces by anion stabilizing solvents and its consequence for catalysis
Fǎrca?iu, Dan,Ghenciu, Anca,Marino, Gaye,Rose, Kenneth D.
, p. 11826 - 11831 (1997)
A comparison of acidity of two solids, a poly(styrenesulfonic acid) (Amberlyst 15) and a perfluoroinated ion exchange polymer (Nafion-H, PFIEP) with the structurally related liquid acids methanesulfonic, sulfuric, and trifluoromethanesulfonic acid (TFMSA), was conducted with mesityl oxide as probe base (determination of the Δδ1 parameter) and for the fluorinated materials also with hexamethylbenzene as the probe base. It was found that Nafion-H is similar in strength to 85% sulfuric acid, whereas Ambelyst 15 is much weaker than 80% methanesulfonic acid or 60% sulfuric acid. Thus, the solids are much weaker acids than their liquid structural analogs. This seems to be a general property, because the rigidity of the solids prevents the acid groups/sites from cooperating in the transfer of a hydron, an essential feature in the manifestation of superacidity. The postulation of superacidity for a number of solid acids appears to have no basis in fact. On the other hand, the acidity of the groups/sites on the surface can be increased by the interaction with a nonbasic solvent, capable of forming strong hydrogen bonds with the anion of the site (anion-stabilizing solvent). The anion-stabilizing solvent generates a new liquid phase around the acid site; for appropriate structures of the solid acid and solvent this phase can be superacidic. The acidity-enhancing effect of the anion-stabilizing solvent was found to have an important effect in boosting the catalytic activity of the solid for carbocationic reactions. A comparison of acidity of two solids, a poly(styrenesulfonic acid) (Amberlyst 15) and a perfluoroinated ion exchange polymer (Nafion-H, PFIEP) with the structurally related liquid acids methanesulfonic, sulfuric, and trifluromethanesulfonic acid (TFMSA), was conducted with mesityl oxide as probe base (determination of the Δδ1 parameter) and for the fluorinated materials also with hexamethylbenzene as the probe base. It was found that Nafion-H is similar in strength to 85% sulfuric acid, whereas Amberlyst 15 is much weaker than 80% methanesulfonic acid or 60% sulfuric aicd. Thus, the solids are much weaker acids than their liquid structural analogs. This seems to be a general property, because the rigidity of the solids prevents the acid groups/sites from cooperating in the transfer of a hydron, an essential feature in the manifestation of superacidity. The postulation of superacidity for a number of solid acids appears to have no basis in fact. On the other hand, the acidity of the groups/sites on the surface can be increased by the interaction with a nonbasic solvent, capable of forming strong hydrogen bonds with the anion of the site (anion-stabilizing solvent). The anion-stabilizing solvent generates a new liquid phase around the acid site; for appropriate structures of the solid acid and solvent this phase can be superacidic. The acidity-enhancing effect of the anion-stabilizing solvent was found to have an important effect in boosting the catalytic activity of the solid for carbocationic reactions.
Isomerization of olefins in a two-phase system by homogeneous water-soluble nickel complexes
Bricout, Herve,Mortreux, Andre,Monflier, Eric
, p. 469 - 471 (1998)
The first example of nickel catalyzed isomerization of olefins in a two-phase system is reported. Provided that the water-soluble ligand is properly tailored and that the Broensted acid is suitably selected, the catalytic system appears relatively stable and high catalytic activity can be reached.
1-hexene oligomerization by fluorinated tin dioxide
Yurkova,Lermontov,Malkova,Baranchikov,Ivanov
, p. 479 - 481 (2014)
Fluorinated tin dioxide has been shown to exhibit catalytic activity for 1-hexene oligomerization. The physicochemical and functional properties of nanocrystalline fluorinated SnO2 have been studied.
Effect of trimethylaluminum on the formation of active sites of the catalytic system bis[N-(3,5-di-tert-butylsalicylidene)-2,3,5,6- tetrafluoroanilinato]titanium(IV) dichloride - MAO and catalytic isomerization of hex-1-ene
Bravaya,Faingol'd,Babkina,Petrova,Makhaev,Gagieva,Tuskaev,Bulychev
, p. 1461 - 1468 (2011)
The transformations of bis[N-(3,5-di-tert-butylsalicylidene)-2,3,5,6- tetrafluoroanilinato]-titanium(IV) dichloride (L2TiCl2) occurring in toluene under the action of methylalumoxane (MAO) were studied by 1H NMR spectroscopy. The commercially available MAO containing trimethylaluminum (AlMe3) and MAO free of AlMe3 (the so called "dry" MAO) were used. The catalytic transformations of hex-1-ene involving the systems L2TiCl2 - MAO were studied. We proposed the structures of the cationic titanium complexes formed in the absence and in the presence of hex-1-ene under the action of MAO. In the absence of olefin, neutral and cationic titanium complexes are decomposed under the action of AlMe3 according to the exchange reaction of the complex ligand with the methyl groups of AlMe3 to form LAlMe2. The neutral complexes react considerably faster than the cationic ones. In the presence of olefin, decomposition of complexes under the action of AlMe 3 is suppressed. The titanium complex activated by "dry" MAO isomerizes hex-1-ene to hex-2-ene. In the presence of large amounts of TMA (commercial MAO), this reaction does not take place.
PH control of the structure, composition, and catalytic activity of sulfated zirconia
Ivanov, Vladimir K.,Baranchikov, Alexander Ye.,Kopitsa, Gennady P.,Lermontov, Sergey A.,Yurkova, Lyudmila L.,Gubanova, Nadezhda N.,Ivanova, Olga S.,Lermontov, Anatoly S.,Rumyantseva, Marina N.,Vasilyeva, Larisa P.,Sharp, Melissa,Pranzas, P. Klaus,Tretyakov, Yuri D.
, p. 496 - 505 (2013)
We report a detailed study of structural and chemical transformations of amorphous hydrous zirconia into sulfated zirconia-based superacid catalysts. Precipitation pH is shown to be the key factor governing structure, composition and properties of amorphous sulfated zirconia gels and nanocrystalline sulfated zirconia. Increase in precipitation pH leads to substantial increase of surface fractal dimension (up to ～2.7) of amorphous sulfated zirconia gels, and consequently to increase in specific surface area (up to ～80 m 2/g) and simultaneously to decrease in sulfate content and total acidity of zirconia catalysts. Complete conversion of hexene-1 over as synthesized sulfated zirconia catalysts was observed even under ambient conditions.
Synthesis of a ni complex chelated by a [2.2]paracyclophane-functionalized diimine ligand and its catalytic activity for olefin oligomerization
Osakada, Kohtaro,Takeuchi, Daisuke,Tojo, Yoshi-Aki
, (2021/05/26)
A diimine ligand having two [2.2]paracyclophanyl substituents at the N atoms (L1) was prepared from the reaction of amino[2.2]paracyclophane with acenaphtenequinone. The ligand re-acts with NiBr2(dme) (dme: 1,2-dimethoxyethane) to form the dibromonickel complex with (R,R) and (S,S) configuration, NiBr2(L1). The structure of the complex was confirmed by X-ray crystallog-raphy. NiBr2(L1) catalyzes oligomerization of ethylene in the presence of methylaluminoxane (MAO) co-catalyst at 10–50 °C to form a mixture of 1-and 2-butenes after 3 h. The reactions for 6 h and 8 h at 25 °C causes further increase of 2-butene formed via isomerization of 1-butene and formation of hexenes. Reaction of 1-hexene catalyzed by NiBr2(L1)–MAO produces 2-hexene via isom-erization and C12 and C18 hydrocarbons via oligomerization. Consumption of 1-hexene of the reaction obeys first-order kinetics. The kinetic parameters were obtained to be ΔG≠ = 93.6 kJ mol?1, ΔH≠ = 63.0 kJ mol?1, and ΔS≠ = ?112 J mol?1deg?1. NiBr2(L1) catalyzes co-dimerization of ethylene and 1-hexene to form C8 hydrocarbons with higher rate and selectivity than the tetramerization of eth-ylene.
Heterometallic Mg?Ba Hydride Clusters in Hydrogenation Catalysis
Wiesinger, Michael,Knüpfer, Christian,Elsen, Holger,Mai, Jonathan,Langer, Jens,Harder, Sjoerd
, p. 4567 - 4577 (2021/09/09)
Reaction of a MgN“2/BaN”2 mixture (N“=N(SiMe3)2) with PhSiH3 gave three unique heterometallic Mg/Ba hydride clusters: Mg5Ba4H11N”7 ? (benzene)2 (1), Mg4Ba7H13N“9 ? (toluene)2 (2) and Mg7Ba12H26N”12 (3). Product formation is controlled by the Mg/Ba ratio and temperature. Crystal structures are described. While 3 is fully insoluble, clusters 1 and 2 retain their structures in aromatic solvents. DFT calculations and AIM analyses indicate highly ionic bonding with Mg?H and Ba?H bond paths. Also unusual H????H? bond paths are observed. Catalytic hydrogenation with MgN“2, BaN”2 and the mixture MgN“2/BaN”2 has been studied. Whereas MgN“2 is only active in imine hydrogenation, alkene and alkyne hydrogenation needs the presence of Ba. The catalytic activity of the MgN”2/BaN“2 mixture lies in general between that of its individual components and strong cooperative effects are not evident.
