- Oxidation of α-pinene by atmospheric oxygen in the supercritical CO2-ethyl acetate system in the presence of Co(II) complexes
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The reactivity of monoterpene α-pinene in a flow reactor in the presence of cobalt catalyst in a complex supercritical solvent consisting of CO2 and ethyl acetate is studied over the temperature range of 190-320°C and a pressure range of 110-125 atm. It was found that the main isomerization products include compounds with bicyclo[2.2.1]heptane and p-menthane backbones; the reaction is accompanied by partial racemization. The formation of oxidation products is observed in the presence of air, with epoxydation rather than allylic oxidation being the predominant process at the first stage. The oxidized products (campholenic aldehyde, verbenone, pinocamphone) are shown to be formed with a high enantioselectivity; the formation of acetoxylation products is observed at temperatures above 200°C.
- Anikeev,Ilina,Kurbakova,Nefedov,Volcho,Salakhutdinov
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experimental part
p. 190 - 195
(2012/03/12)
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- Synthesis of nopol via Prins condensation of β-pinene and paraformaldehyde catalyzed by sulfated zirconia
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The present work describes the novel application of sulfated zirconia (SZ) solid acid catalysts for the synthesis of nopol via Prins condensation of β-pinene and paraformaldehyde. SZ catalysts with different percentages of sulfur loadings have been synthesized and characterized using various physico-chemical techniques like PXRD, FT-IR, surface area analysis and NH 3-TPD studies. The influences of various reaction parameters such as sulfur loading, reaction temperature, molar ratio of reactants, reaction time, solvent effect and reusability of the catalyst have been investigated. SZ catalyst synthesized by impregnation of 2N sulfuric acid solution over Zr(OH)4 was found to be a highly selective catalyst for β-pinene conversion (>99%) with ～99% selectivity to nopol. The catalyst could be reused up to five cycles with minor loss in catalytic activity for β-pinene conversion, while the nopol selectivity remains unaffected.
- Jadhav, Sumit V.,Jinka, Krishna Mohan,Bajaj, Hari C.
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scheme or table
p. 158 - 165
(2011/12/21)
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- Chloromethanesulfonate as an efficient leaving group: Rearrangement of the carbon-carbon bond and conversion of alcohols into azides and nitriles
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The chloromethanesulfonate (monochlate) served as an efficient leaving group for rearrangement of the carbon-carbon bond and conversion of alcohols into azides and nitriles. The treatment of the monochlate 16a with zinc acetate in dioxane at 90 °C effected migration of the 4α-methyl group to give alkene 17a. Upon similar treatment of the monochlates 22a, 25a, 28a, and 31a with zinc acetate, the carbon-carbon bonds antiperiplanar to the hydroxyl groups efficiently migrated to afford the alkenes 23a, 26a-c, 29a,b, and 32a, respectively. In the case of the diol 40, the monochlate was converted into the ketone 41 via a rearrangement-ring expansion. The reaction of the monochlates 44a, 47a, 49a, 52a, and 57a with sodium azide or lithium azide in N,N-dimethylformamide efficiently afforded the azides with inversion of the configuration. The introduction of a nitrile group to the sterically hindered alcohol 59 was performed in high yield by the reaction of the monochlate 60a with sodium cyanide.
- Shimizu, Takeshi,Ohzeki, Tomoya,Hiramoto, Katsuya,Hori, Nobuyuki,Nakata, Tadashi
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p. 1373 - 1385
(2007/10/03)
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- Alkylmetal Asymmetric Reduction. 18. Starting Materials in the Preparation of New Chiral Reducing Agents: Synthetic Approach to Primary Alkyl Halides Derived from (+)-Camphor
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2,2-Dimethyl-3-(chloromethyl)bicycloheptane (camphanyl chloride), camphanyl bromide, 1,7,7-trimethyl-2-(chloromethyl)bicycloheptane , and 2-(bromomethyl)bornane were prepared from (+)-camphor.All these compounds were obtained as mixture of exo and endo isomers in various ratios depending upon the synthetic path adopted.A loss of diastereomeric purity during the halogenations of corresponding alcohols was observed.
- Falorni, Massimo,Lardicci, Luciano,Giacomelli, Giampaolo
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p. 5291 - 5294
(2007/10/02)
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- Preparation of Chiral 1-Deuteriobenzenemethanethiols by Using α',β Elimination of Carbanions Derived from Benzylic Thioethers
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The α',β elimination of the carbanion derived from benzyl isolongifolyl thioether and benzyl camphyl thioether gives the chiral benzyl mercaptan, the S isomer with 38 +/- 6percent ee and the R isomer with 49 +/- 7percent ee.The chirality of the benzyl mercaptan was determined by optical rotation of benzyl methyl thioether and thiosulfone.The enantiomeric excess was evaluated from 1H NMR measurement of ethyl (benzylthio)phenylacetate prepared from (-)-mandelic acid.The enantiomeric excess at carbon C-2 of ethyl (benzylthio)phenylacetate wasdetermined with the chiral europium chelate and was about 60percent.These results are discussed with reference to the transition state of the α,β elimination and to related processes.
- Biellmann, Jean-Francois,d'Orchymont, Hugues
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p. 2882 - 2886
(2007/10/02)
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- Amines as Dehalogenating Agents. IV. Hydrocarbons, N-Bornyl- and N-Isobornylaniline Formation in the Reaction between 3-Bromocamphor and N-Methylaniline
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N-Methylanilin (4) reagiert bei 200 deg C im Vergleich zu N,N-Dimethylanilin entweder mit 3-Bromcamphor (2) oder Camphor (3) zu den Kohlenwasserstoffen, Camphen 5 und Tricyclen 6 und N-Bornylanilin (exo-endo-Isomers 7).Bei der Reaktion mit 3 ist Saeurekatalyse notwenig.Untersuchungen zum Mechanismus erlauben es, anzunehmen, dass Camphoranil 8 ein gemeinsames Zwischenprodukt fuer alle Produkte und 4 der H-Donator in den Reduktionsstufen ist, auf der Grundlage von kinetischen und stereochemischen Beweisen und unabhaengigen chemischen Experimenten.
- Giumanini, Angelo G.,Musiani, Marco M.
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p. 423 - 428
(2007/10/02)
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