The Lossen rearrangement is a classic process for transforming activated hydroxamic acids into isocyanate under basic or thermal conditions. In the current report we disclosed a consecutive Lossen rearrangement/transamidation reaction in which unactivated hydroxamic acids were converted into N-substituted formamides in a one-pot manner under catalyst- and additive-free conditions. One feature of this novel transformation is that the formamide plays triple roles in the reaction by acting as a readily available solvent, a promoter for additive-free Lossen rearrangement, and a source of the formyl group in the final products. Acyl groups other than formyl could also be introduced into the product when changing the solvent to other low molecular weight aliphatic amide derivatives. The solvent-promoted Lossen rearrangement was better understood by DFT calculations, and the intermediacy of isocyanate and amine was supported well by experiments, in which the desired products were obtained in excellent yields under similar conditions. Not only monosubstituted formamides were synthesized from hydroxamic acids, but also N,N-disubstituted formamides were obtained when secondary amines were used as precursors.
In this work, a free-standing sodium titanate ultralong nanotube membrane for multifunctional water purification has been prepared. For obtaining this free-standing membrane with good tenacity, one-dimensional (1D) sodium titanate ultralong nanotubes with a diameter of about 48 nm and length of hundreds of micrometers were prepared from TiO 2 nanoparticles by a stirring hydrothermal method, which can be easily assembled into 2D membranes by facile vacuum filtration. After modified with methyltrimethoxysilane (MTMS), the free-standing membrane with hydrophobic surface possesses oil-water separation, self-cleaning and photocatalytic functions at the same time, which is favorable for the recovery of membrane and decontamination of various pollutants including oils, dust, and organic dyes from water. Furthermore, this membrane also exhibits excellent alkaline, acid, and corrosive salt resistance. This free-standing sodium titanate membrane with multifunction has potential applications in efficient wastewater purification and environmental remediation.
Am echanistic understanding of the rhodium(III)catalyzed doubleC ÀHa ctivation for oxidative annulations of 2-substituted imidazoles and alkynes was achieved by density functional theory calculations. It is disclosed that the rhodium(III)-acetate-triggered CÀHb ond cleavage occurs with-out ad irecting group, and the C5ÀHc leavage has the lowest activation barriera mong all possible CÀHa ctivation processes.T he experimental observationsi nr eactions of different imidazole derivatives were explained well by the theoretical results.Scheme1.Strategies for transition-metal-catalyzed CÀHa ctivation. DG = directing group, Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl.
Plasmon-mediated photocatalysts composed of Au nanoclusters and ultrathin Zn0.5Cd0.5S nanorods (Au/ZCS NRs) were synthesized by a facile method. All Au/ZCS samples present significant improvement for dyes degradation under visible light....
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