- ZrO2-SiO2 mixed oxides xerogel and aerogel as solid acid catalysts for solvent free isomerization of α-pinene and dehydration of 4-methyl-2-pentanol
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Sulfated and non-sulfated ZrO2-SiO2 mixed oxide xerogel and aerogel samples having varied Zr/Si molar ratio were evaluated as solid acid catalysts for the isomerization of α-pinene and dehydration of 4-methyl-2-pentanol. Sulfation resulted into enhancement in the catalytic activity of both xerogel and aerogel samples towards the studied reactions. For example, sulfated catalysts showed 86-98% conversion of α-pinene and 8-35% conversion of 4-methyl-2-pentanol. The selectivity data for camphene and limonene indicated the requirement of moderate acidity. The correlation with cyclohexanol dehydration showed that isomerization of α-pinene is a Bronsted acid catalyzed reaction. The relationship of 4-methyl-2-pentanol conversion with acid site density and sulfur per unit area was found to be linear.
- Sidhpuria, Kalpesh B.,Tyagi, Beena,Jasra, Raksh V.
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experimental part
p. 1164 - 1170
(2012/06/30)
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- NOVEL PRODUCTS FROM BECKMANN FRAGMENTATION OF CAMPHOR OXIME IN POLYPHOSPHORIC ACID
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Heating camphor oxime with PPA affords, besides the known fragmentation products isoaminocamphor (4) and β-campholenonitrile (13), four isomeric ketones C10H14O resulting from intramolecular acylation of the intermediate α-campholenonitrile (3).The ketones have been identified as 5-ketocamphene (6), 6-ketocamphene (8), tricyclenone (9), and endo-2,4-dimethylbicyclooct-2-ene-7-one (14).The latter results from a novel ring expansion, probably by way of a protonated cyclopropane.
- Hill, Richard K.,McKinnie, B. Gary,Conley, Robert T.,Darby, Paul S.,Halbeek, Herman van,Holt, Elizabeth M.
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p. 3405 - 3412
(2007/10/02)
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- Liquid Crystalline Catalysis, 3, Monomolecular Rearrangements of Terpene Derivatives in Liquid Crystalline Solvents
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The ability of limonene and linalool to rearrange in mesomorphic media is apparently determined by the constraints exerted by the solvent structure on the translational diffusions of the reactant solute molecules.Selective conversions seem to be promoted by the different media.Alkylcyclohexyl- and alkylbicyclohexyl-carboxylic acids and their mixtures with toluic acid have been used as solvents.The B structure of their smectic phases has been demonstrated by X-ray diffraction studies.
- Melone, S.,Mosini, V.,Nicoletti, R.,Samori, B.,Torquati, G.
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p. 399 - 410
(2007/10/02)
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- Dehydrogenation of β-Pinene to p-Cymene over Platinum-Alumina Catalyst in the Presence of Nitrogen, Hydrogen and Pyridine
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Dehydrogenation of β-pinene has been carried out over platinum-alumina (0.6percent Pt) catalyst at 300 deg C in the presence of nitrogen, hydrogen and pyridine.Nitrogen acts as a diluent while hydrogen acts both as a diulent and as a promoter.Pyridine on the other hand functions as a diluent and as a poison.As a result, it affects the formation of different products to different extent.The optimum conditions such as platinum concentration, temperature and contact time for dehydrogenation, hydrogenation and disproportionation reactions were established using cyclohexane, p-cymene and cyclohexene, respectively before actually studying the d ehydrogenation of β-pinene.
- Krishnasamy, V.,Mathur, Pravin,Chandrasekharan, K.
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- Effect of Sulfate Ions on Activity of TiO2, Fe2O3 and ZrO2 for the 2-Pinene Isomerization Reaction
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Treatment of titanium oxide, Fe2O3 and ZrO2 with (NH4)2SO4 brought high catalytic activity for isomerization of 2-pinene.The selectivities of the catalysts for formation of camphene and 1,7,7-trimethyltricyclo2.6>heptane(tricyclene) were high (60-70 percent).The effect of sulfate ions has been interpreted in terms of surface acid strenght.Key words: Oxides / Sulphate ion / Isomerization / 2-Pinene
- Ohnishi, Ryuichiro,Morikawa, Toshiyuki,Hiraga, Yoshizumi,Tanabe, Kozo
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p. 205 - 210
(2007/10/02)
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- Isomerization of β-pinene in the Vapour Phase over Alumina Catalyst: Influence of Partial Pressure of Nitrogen and Pyridine
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The isomerization of β-pinene in the vapour phase over alumina catalyst has been studied in the presence of nitrogen and pyridine.The isomerization proceeds via two parallel paths, one giving bicyclic products such as α-pinene and camphene and the other giving rise to monocyclic menthadienes such as dipentene, terpinolene, α-terpinene and γ-terpinene.Nitrogen acts as a diluent while pyridine functions as a diluent and as a poison.As a result, it affects the formation of different products to different extent.The isomerization of β-pinene over alumina follows a second order kinetics.Based on the experimental facts a tentative mechanism, in terms of carbonium ion intermediates, has been proposed.
- Krishnasamy, V.,Ratansamy, P.
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p. 1151 - 1154
(2007/10/02)
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