- Direct conversion of carboxylic acids (Cn) to alkenes (C2n - 1) over titanium oxide in absence of noble metals
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Carbon-carbon bond formations and deoxygenation reactions are important for biomass up-grading. The classical ketonic decarboxylation of carboxylic acids provides symmetrical ketones with 2n + 1 carbon atoms and eliminates three oxygen atoms. Herein, this reaction is carried out with titanium oxide at 400°C, and an olefin with 2n + 1 carbon atoms is obtained instead of the ketone. For olefin formation hydrogen transfer reactions are required from suitable precursors to form aromatics and coke. Additional aldol condensation reactions increase further molecular weight in the product mixture. Hence, a combination of titanium oxide with a hydrodeoxygenation bed provides double amount of diesel fuel as the combination with zirconium oxide when reacting hexose-derived pentanoic acid.
- Oliver-Tomas, Borja,Renz, Michael,Corma, Avelino
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- Carbon-carbon bond formation by electrochemical catalysis in conductive microemulsions
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Bicontinuous microemulsions made from oil, water, and surfactants were examined as substitutes for organic solvents in carbon-carbon bond-forming reactions. Conjugated additions of primary alkyl iodides 3a-c to 2-cyclohexen-1-one (4) to give 3-alkyl cyclohexanones 5a-c and cyclization of 2-(4-bromobutyl)-2-cyclohexen-1-one (9) to 1-decalone (10) were mediated by the Co(I)L complex vitamin B12s generated at carbon cloth electrodes under mild conditions. Reaction of the Co(I)L nucleophile with the alkyl halides gives a Co-alkyl complex. Cleavage of the Co-alkyl complexes by using an electrode potential of -0.85 V (all vs SCE) and irradiation with visible light, or a potential of -1.45 V in the dark, were compared. Addition of the resulting alkyl radicals to the activated double bonds gave comparable yields of 3-alkylcyclohexanone 5a-c (70-80% using -0.85 V + light) and 1-decalone (90%, both cleavage modes) 10 in microemulsions and in DMF. Microemulsions containing hexadecyltrimethylammonium bromide (CTAB) gave remarkable stereoselectivity for the trans isomer of 10, while homogeneous DMF and a sodium dodecylsulfate (SDS) microemulsion gave little stereoselectivity.
- Gao, Jianxin,Rusling, James F.,Zhou, De-Ling
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p. 5972 - 5977
(2007/10/03)
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- Studies of the synthesis of 8a-hydroxy-4a-methyloctahydronaphthalen-1(2H)-ones and their 2α-deutero derivatives
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Two syntheses of the bicyclic α-ketols, 8a-hydroxy-4a-methyl-trans- and -cis-octahydronaphthalen-1(2H)-ones (1 and 2), have been effected.One involves epoxidation of 4a-methyl-1,2,3,4,4a,5,6,7-octahydronaphthalene (4), followed by hydrolysis and oxidation; direct "hydroxy ketonization" of 4 was found not to be practicable.The second involves treatment of 3,4,5,6,7,8-hexahydronaphthalen-1(2H)-one (14) with lithium dimethylcuprate, trimethylsilylation of the resulting enolate, oxidation of the enol ether, and hydrolysis.Syntheses of the 2α-deutero derivatives of 1 and 2 are also described.
- Stiver, Shirley,Clark, Peter D.,Yates, Peter
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