In the present work, the dimethyl carbonate (DMC)−methanol binary mixture was used as a benchmark system to study the molecular structures of the liquid/vapor interface of organic−organic mixtures by sum frequency generation vibrational spectroscopy (SFG-VS) and molecular dynamics (MD) simulations. It was discovered that both the methanol and DMC molecules are anisotropically oriented at the surface, yielding strong SFG-VS signals in the C−H stretching frequency range for both molecules. The detailed analyses of the spectroscopic and MD data reveal that the increase of the methanol bulk concentrations reduces the orientational order of the methyl groups for both the interfacial DMC and methanol molecules but does not significantly affect the orientations of the carbonyl group in DMC. Moreover, no obvious correlations were found between the room-temperature orientations of the surface molecules and the azeotropic mole fraction. The present work paves the road for future investigations on the molecular structures of the liquid/vapor interfaces of other organic−organic mixtures, especially those that are important in industrial separations.

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As an attractive alternative technology for the separation of long chain olefin and paraffin, a novel silver‐based deep eutectic solvent (Ag‐DES) was prepared and utilized for 1‐octene/n‐octane separations. Comprehensive reactive extraction separation experiments were performed to highlight the Ag‐DES concentration and operating temperature discriminations using compounds with different ratio of 1‐octene/n‐octane. The novel Ag‐DES showed optimal separation performance regarding 1‐octene/n‐octane and possessed the highest levels separation selectivity in the range 3.57–16.11 with excellent circulation stability in our best knowledge. Furthermore, FT‐Raman measurements and quantum chemistry calculation were performed to elucidate the interaction mechanism of Ag‐DES in the separation of 1‐octene and n‐octane, which revealed that both chemical complexation and strong physical attraction existed in the complex of Ag‐DES and 1‐octene rather than n‐octane. A practical process was proposed for the separation of olefin and paraffin, which indicates that an advanced separation technology could largely reduce the energy consumption. This study lends important insight for the development of Ag‐DES reactive extraction separation process for the energy‐efficient long chain α‐olefins purification from F‐T synthesis products.