A novel approach for toluene gas treatment using a downflow hanging sponge reactor.

A novel gas-scrubbing bioreactor based on a downflow hanging sponge (DHS) reactor was developed as a new volatile organic compound (VOC) treatment system. In this study, the effects of varying the space velocity and gas/liquid ratio were investigated to assess the effectiveness of using toluene gas as a model VOC. Under optimal conditions, the toluene removal rate was greater than 80%, and the maximum elimination capacity was observed at approximately 13 g-C m-3 h-1. The DHS reactor demonstrated slight pressure loss (20 Pa) and a high concentration of suspended solids (up to 30,000 mg/L-sponge). Cloning analysis of the 16S rRNA and functional genes of toluene degradation pathways (tmoA, todC, tbmD, xylA, and bssA) revealed that the clones belonging to the toluene-degrading bacterium Pseudomonas putida constituted the predominant species detected at the bottom of the DHS reactor. The toluene-degrading bacteria Pseudoxanthomonas spadix and Pseudomonas sp. were also detected by tmoA- and todC-targeted cloning analyses, respectively. These results demonstrate the potential for the industrial application of this novel DHS reactor for toluene gas treatment.

Indium-Catalyzed [2 + 2] Cycloaddition of Allylsilanes to Internal Alkynones.

We have developed an indium-catalyzed [2 + 2] cycloaddition of allylsilanes to alkynones leading to selective cyclobutenone formation. The resulting cyclobutenones were readily converted to the oxidized products by Tamao-Fleming oxidation or the ring-opened products by an electrocyclic reaction.

Stereoselective construction of 1,3-disilylcyclopentane derivatives by scandium-catalyzed [3+2] cycloaddition of allylsilanes to ß-silylenones.

The Sc(OTf)3-catalyzed [3+2] cycloaddition of allylsilanes to ß-silyl-α,ß-unsaturated ketones (ß-silylenones) has been developed to form five-membered syn-1,3-disilylketones diastereoselectively through the rearrangement of the silicon substituents on the allylsilane. Stabilization of the carbocation intermediates by a double silicon effect plays a key role in directing the course of the reaction to favor the [3+2] cycloaddition pathway over simple allylation.

Palladium-catalyzed aza-Wittig-type condensation of isoxazol-5(4H)-ones with aldehydes.

This paper describes the development of a palladium-catalyzed decarboxylative inter- and intramolecular condensation reaction of isoxazol-5(4 H)-ones with carbonyl compounds in the presence of PPh3 , giving various 2-azabuta-1,3-dienes or pyrroles in moderate to high yields.

Acid-catalyzed direct conjugate alkenylation of α,ß-unsaturated ketones.

New tricks, old reaction: The title reaction proceeds under mild and transition-metal-free conditions (see scheme; Tf=trifluoromethanesulfonyl). Various combinations of substrates are applicable to the synthesis of γ,δ-unsaturated ketones by employing silicon substituents at the ß-position of the enones. The silicon substituents play a key role in stabilization of the cationic intermediate by hyperconjugation.