Ionic Liquid, [bmim]Br, as an Efficient Promoting Medium for Synthesis of 3-Acetoacetylcoumarin Derivatives Without the Use of Any Catalyst

Dynamic Wetting of Ionic Liquid Drops on Hydrophobic Microstructures

Ionic liquids (ILs)─salts in a liquid state─play a crucial role in various applications, such as green solvents for chemical synthesis and catalysis, lubricants, especially for micro- and nanoelectromechanical systems, and electrolytes in solar cells. These applications critically rely on unique or tunable bulk properties of ionic liquids, such as viscosity, density, and surface tension. Furthermore, their interactions with different solid surfaces of various roughness and structures may uphold other promising applications, such as combustion, cooling, and coating. However, only a few systematic studies of IL wetting and interactions with solid surfaces exist. Here, we experimentally and theoretically investigate the dynamic wetting and contact angles (CA) of water and three kinds of ionic liquid droplets on hydrophobic microstructures of surface roughness (r = 2.61) and packing fraction (ϕ = 0.47) formed by micropillars arranged in a periodic pattern. The results show that, except for water, higher-viscosity ionic liquids have greater advancing and receding contact angles with increasing contact line velocity. Water drops initially form a gas-trapping, CB wetting state, whereas all three ionic liquid drops are in a Wenzel wetting state, where liquids penetrate and completely wet the microstructures. We find that an existing model comparing the global surface energies between a CB and a Wenzel state agrees well with the observed wetting states. In addition, a molecular dynamic model well predicts the experimental data and is used to explain the observed dynamic wetting for the ILs and superhydrophobic substrate. Our results further show that energy dissipation occurs more significantly in the three-phase contact line region than in the liquid bulk.

Synthesis of 3-[(coumarinyl)carbonyl]-3a,8b-dihyroindeno[1,2-b]pyrrole-4(1H)-ones and their conversion to coumarin bearing spiro[isobenzofuran-1,2′-pyrrole] moiety compounds via oxidative cleavage reaction

The synthesis of substituted coumarin derivatives bearing indenopyrrole and spiro[isobenzofuran-1,2′-pyrrole] in a four-component sequential reaction and following oxidative cleavage reaction.

Dynamic wetting of a fluoropolymer surface by ionic liquids

The spontaneous spreading of ionic liquids on a fluoropolymer surface (Teflon AF1600) in air is investigated by high-speed video microscopy. Six ionic liquids (EMIM BF(4), BMIM BF(4), OMIM BF(4), EMIM NTf(2), BMIM NTf(2) and HMIM NTf(2)) are used as probe liquids. The dependence of the dynamic contact angle on contact line velocity is interpreted with a hydrodynamic model and a molecular-kinetic model. The usefulness of the hydrodynamic model is rather limited. There is a good correspondence between the molecular dimensions of the liquids and the physical parameters of the molecular-kinetic model. The viscous and molecular-kinetic contributions to energy dissipation are calculated, revealing that energy is dissipated in the bulk as well as at the contact line during dynamic wetting. There are wide ramifications of these results in areas ranging from lubrication and biology to minerals processing and petroleum recovery.

Efficient one-pot synthesis of novel spirooxindole derivatives via three-component reaction in aqueous medium

A novel and efficient one-pot synthesis of spiro[indoline-3,4'-pyrazolo[3,4-b]quinoline]dione, spiro[furo[3,4-e]pyrazolo[3,4-b]pyridine-4,3'-indoline]dione, and spiro[indeno[2,1-e]pyrazolo[3,4-b]pyridine-4,3'-indoline]dione derivatives via three-component reaction of isatin, 5-amino-3-methylpyrazole, and 1,3-dicarbonyl compounds in aqueous medium is described. The advantages of this method include high efficiency, mild reaction conditions, convenient operation, and environmentally benign conditions.

Ionic liquid 1-butyl-3-methylimidazolium bromide ([bmim]Br): A green and neutral reaction media for the efficient, catalyst-free synthesis of quinoxaline derivatives

Quinoxaline derivatives were produced in excellent yields and short reaction times via the condensation of 1,2-diamines with 1,2-diketones in the neutral ionic liquid 1-butyl-3-methylimidazolium bromide ([bmim]Br) under catalyst-free and microwave irradiation conditions.