2623-54-3Relevant academic research and scientific papers
Acidic property of FSM-16
Yamamoto, Takashi,Tanaka, Tsunehiro,Funabiki, Takuzo,Yoshida, Satohiro
, p. 5830 - 5839 (1998)
Siliceous FSM-16 possesses acid sites to catalyze but-1-ene isomerization to produce but-2-ene (cis/trans = 1.4-1.7) at 323 K and 2,6,6- trimethylbicyclo[3.1.1]hept-2-ene (α-pinene) isomerization at 303 K. Catalytic activity was dependent upon heat treatment and reached a maximum at 673 K. The maximum acid strength was invariably H0 = -3.0 independent of the pretreatment temperatures. The acidity was much reduced by calcination at higher temperatures, but restored by water treatment at 353 K as long as the FSM-16 retained its structure.
Supported H4SiW12O40 catalysts for α-pinene isomerization
Szuecs-Balazs, Jozsef-Zsolt,Coros, Maria,Woiczechowski-Pop, Adrian,Blanita, Gabriela,Vlassa, Mircea
, p. 1208 - 1217 (2012/11/13)
The heterogeneous isomerization of α-pinene was studied at 100, 130 and 160°C using 10% supported H4SiW12O40 (SiW) on SiO2, TiO2 and HZSM-5. The effect of the reaction temperature and the concentratio
Cloning and characterization of Pfl-1841, a 2-methylenebornane synthase in Pseudomonas fluorescens PfO-1
Chou, Wayne K.W.,Ikeda, Haruo,Cane, David E.
supporting information; experimental part, p. 6627 - 6632 (2011/10/04)
The pfl-1841 gene from Pseudomonas fluorescens PfO-1 is the only gene in any of the three sequenced genomes of the Gram-negative bacterium P. fluorescens, that is, annotated as a putative terpene synthase. The predicted Pfl-1841 protein, which harbors the two strictly conserved divalent metal binding domains found in all terpene cyclases, is closely related to several known or presumed 2-methylisoborneol synthases, with the closest match being to the MOL protein of Micromonaspora olivasterospora KY11048 that has been implicated as a 2-methylenebornane synthase. A synthetic gene encoding P. fluorescens Pfl-1841 and optimized for expression in Escherichia coli was expressed and purified as an N-terminal His6-tagged protein. Incubation of recombinant Pfl-1841 with 2-methylgeranyl diphosphate produced 2-methylenebornane as the major product accompanied by 1-methylcamphene as well as other minor, monomethyl-homomonoterpene hydrocarbons and alcohols. The steady-state kinetic parameters for the Pfl-1841-catalyzed reaction were K M=110±13 nM and kcat=2.4±0.1×10 -2 s-1. Attempts to identify the P. fluorescens SAM-dependent 2-methylgeranyl diphosphate synthase have so far been unsuccessful.
Generation of acid sites on silica-supported rare earth oxide catalysts: Structural characterization and catalysis for α-pinene isomerization
Yamamoto, Takashi,Matsuyama, Takahiro,Tanaka, Tsunehiro,Funabiki, Takuzo,Yoshida, Satohiro
, p. 2841 - 2849 (2007/10/03)
Silica-supported rare earth oxide catalysts (Ln/SiO2; Ln = La, Ce, Pr, Sm, Eu, Tb, Yb and Y), loading amounts of which were 3.4 mmol g (support)- 1, were characterized by α-pinene isomerization, temperature-programmed desorption (TPD), Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), thermogravimetric-differential thermal analysis (TG-DTA) and Raman spectroscopy. In the lanthanoid series, the catalytic activity increased with atomic number from 57La to 70Yb, except for Ce. All the Ln/SiO2 catalysts, except for Ce, were amorphous. On the surface of the catalyst, Ln-O-Si and Ln-O-Ln linkages formed, the ratio of which varied with the loaded element. The ratio of Ln-O-Si linkage increases with stronger affinity among LnO(n) units and SiO4 tetrahedra, and the affinity depends on the size of Ln3+. With increasing ratio of Ln-O-Si to Ln-O-Ln linkage, the catalytic activity increases. Silica-supported yttrium oxide catalyst, the trivalent ion radius of which is quite similar to that of ytterbium, exhibited the same activity as that of Yb/SiO2. Raman spectroscopic characterization revealed that excess loading of Yb atoms on SiO2-support block Yb-O-Si linkage to form Yb2O3 fine particles. When Yb/SiO2 was pretreated at 1273 K, fine ytterbium silicate crystallites formed. Ln-O-Si linkage without a long-ranged ordering structure was the active site for α-pinene isomerization.
Liquid-phase isomerization of α-pinene on a natural clinoptilolite
Allakhverdiev,Sokolova,Gunduz,Kul'kova
, p. 1647 - 1650 (2007/10/03)
The liquid-phase isomerization of α-pinene on a suspended powder (50-100 μm) of a natural clinoptilolite is studied. It is found that thermoevacuation at 500°C decreases the catalyst's activity and selectivity. The surface acidity decreases, whereas the surface concentration of Fe2+ ions increases. The reaction mechanism is proposed.
Structural Effects in Solvolytic Reactions. 49. Steric Effects as a Major Factor in the Exo:Endo Rate Ratios for the Solvolysis of 2,7,7-Trimethyl- and 2,6,6-Trimethyl-2-norbornyl p-Nitrobenzoates
Brown, Herbert C.,Ikegami, Shiro,Jagt, Dawid L. Vander
, p. 1165 - 1171 (2007/10/02)
The exo:endo rate ratio for solvolysis, in 80percent aqueous acetone at 25 deg C, decreases from 885 for 2-methyl-2-norbornyl p-nitrobenzoate to 6.1 for 2,7,7-trimethyl-2-norbornyl p-nitrobenzoate.On the other hand, it increases remarkably to 3 630 000 in the case of 2,6,6-trimethyl-2-norbornyl p-nitrobenzoate.These changes are clearly attributable to steric effects caused by the syn methyl group at the 7- and 6-positions, respectively.In the 2,7,7-trimethyl-2-norbornyl system, the very low exo:endo rate ratio arises primarily from an increased rate of solvolysis of the endo isomer, attributed to relief in steric strain, involving the syn 7-methyl and exo 2-methyl groups, during ionization.The extremely large exo:endo rate ratio in the 2,6,6-trimethyl-2-norbornyl system is attributed to the high rate of solvolysis of the exo isomer, caused by the relief in steric strain involving the endo 2-methyl and endo 6-methyl groups, as well as an especially slow rate for the endo isomer, caused by enhanced steric retardation of ionization.Thus, these results show clearly that exo:endo rate ratios can be strongly affected by steric effects in the rigid norbornyl system.
