- A catalytic conversion method for preparing pyruvate ester of lactic acid (by machine translation)
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A method for preparing pyruvate through catalytic conversion of lactic acid is provided; according to the method, with oxygen or air as an oxidant, alcohol as a solvent, and molybdovanadophosphoric heteropoly acid and/or tungstovanadophosphoric heteropoly acid as a catalyst, and by coupling of a catalytic oxidation reaction and an esterification reaction, lactic acid is converted into pyruvate by one step. The method directly adopts oxygen or air as the oxidant and is green and safe; the used raw material lactic acid is obtained directly from conversion of biomass resources, moreover, the reaction conditions are mild, and the method has important application prospects.
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- Method for producing enol ethers
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Enol ethers of the formula I where R1is an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical which may carry further substituents which do not react with acetylenes or allenes, and the radicals R, independently of one another, are hydrogen or aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radicals, which may be bonded to one another to form a ring, and m is 0 or 1, are prepared by reacting an acetal or ketal of the formula II with an acetylene or allene of the formula III or IV where R and R1have the abovementioned meanings, in the gas phase at elevated temperatures in the presence of a zinc- or cadmium- and silicon- and oxygen-containing heterogeneous catalyst.
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- Formation of Δ4-oxocenes from Lewis acid promoted cyclizations of 5-hexenyl acetals. Evidence for a concerted ene cyclization mechanism
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Both the intermolecular (kinetic) and intramolecular (product) hydrogen-deuterium isotope effects were determined to be 1.65 for the formation of 2-methyl-4-(trimethylsilyl)-Δ4-oxocene (20) from the SnCl4-promoted cyclization of acetals 19, 30, and 31 (eq 6). In other experiments silyl acetal 32 was found to cyclize in the presence of SnCl4 to form the silyl-Δ4-oxocene 34 and the alkylideneoxepane 35 in 2:1 ratio (eq 7). Both results provide strong evidence that the formation of 4-(trimethylsilyl)-Δ4-oxocenes from SnCl4-promoted cyclizations of 5-(trimethylsilyl)-5-hexenyl acetals takes place by a concerted intramolecular ene mechanism. Also reported are SnCl4-promoted exchange reactions of formaldehyde- and aldehyde-derived acetals, which occur readily at -10 to 0 °C and -70 °C, respectively (eqs 2 and 3).
- Blumenkopf, Todd A.,Look, Gary C.,Overman, Larry E.
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p. 4399 - 4403
(2007/10/02)
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