RESUMEN
The direct conversion of low alkane such as ethane into high-value-added chemicals has remained a great challenge since the development of natural gas utilization. Herein, we achieve an efficient one-step conversion of ethane to C2 oxygenates on a Rh1/AC-SNI catalyst under a mild condition, which delivers a turnover frequency as high as 158.5 h-1. 18O isotope-GC-MS shows that the formation of ethanol and acetaldehyde follows two distinct pathways, where oxygen and water directly participate in the formation of ethanol and acetaldehyde, respectively. In situ formed intermediate species of oxygen radicals, hydroxyl radicals, vinyl groups, and ethyl groups are captured by laser desorption ionization/time of flight mass spectrometer. Density functional theory calculation shows that the activation barrier of the rate-determining step for acetaldehyde formation is much lower than that of ethanol, leading to the higher selectivity of acetaldehyde in all the products.
RESUMEN
L-histidine is a promising alternative to expensive protein ligands for the adsorption of IgG due to its high selectivity, no toxicity and low cost; while click chemistry can improve the reaction selectivity between the ligands and the support matrix under mild reaction conditions. Thus, using L-histidine as a ligand and original sepharose gel as a support, a novel immunoadsorbent possessing pseudo-biospecific affinity for IgG from human plasma, Sep-triazole-His, was designed and prepared according to the principle of Click-reaction between alkyne and azide functional groups; while both sepharose-based control samples Sep-His and Sep-PA were prepared by a conventional method using L-histidine and protein A as a ligand, respectively. The ligand density and IgG adsorption performance of Sep-triazole-His from human plasma were measured and evaluated. The influences of click chemistry on the preparation, structure and performance of sepharose-based immunoadsorbent were also investigated. The results indicate that the ligand density immobilized on Sep-triazole-His is 319.1 µmol/g sepharose gel, almost 4-fold as high as that on Sep-His; the IgG adsorption capacity of Sep-triazole-His from human plasma reaches 16.49 mg/g at pH 7.0, or increases 5.72-fold with respect to Sep-His, and does not decrease noticeably after being repeatedly used for 10 times; and Sep-triazole-His can exhibit high adsorption selectivity for IgG comparable to Sep-PA. The further studies prove that the 1,2,3-triazole ring in the spacer-arm of Sep-triazole-His, can facilitate the binding of IgG without non-specific adsorption.
