Atom-Economical Synthesis of N-Arylamides Utilizing Isopropenyl Esters with Heterogeneous Acid Catalysts.

Existing methods for the catalytic synthesis of N-arylamides are limited by a narrow substrate scope, high catalyst costs, and complicated purification processes of products. To overcome these limitations, this study developed an ecofriendly method for the synthesis of N-arylamides using isopropenyl esters. Isopropenyl esters activated using heterogeneous acid catalysts reacted smoothly even with less reactive arylamines to afford N-arylamides in high yields. This method exhibits a wide substrate scope and is applicable for the synthesis of various N-arylamides (33 examples, 46-99% yield). The developed method enabled the obtainment of high-purity products with a facile workup procedure and showed excellent process mass intensity values due to the reduction of chemical waste.

Rapid and continuous fabrication of TiO2 nanoparticles encapsulated by polyimide fine particles using a multistep flow-system and their application.

PI fine particles encapsulating a large number of TiO2 nanoparticles (PI FPs/TiO2 NPs) were successfully fabricated rapidly and continuously by the emulsion re-precipitation method using a multistep flow synthetic system. The fabricated material, PI FPs/TiO2 NPs, was spherical in structure with a diameter of 214 nm, and the mean size of TiO2 NPs was 5.2 nm. Line scan elemental analysis with SEM-EDX showed that the TiO2 NPs were disproportionately embedded near the surface of the PI FPs. UV-vis transmission spectra revealed high UV shielding efficiency of the PI FPs/TiO2 NPs as the NPs are located near the surface.

Defining Pt-compressed CO2 synergy for selectivity control of furfural hydrogenation.

The development of a sustainable methodology for catalytic transformation of biomass-derived compounds to value-added chemicals is highly challenging. Most of the transitions are dominated by the use of additives, complicated reaction steps and large volumes of organic solvents. Compared to traditional organic solvents, alternative reaction media, which could be an ideal candidate for a viable extension of biomass-related reactions are rarely explored. Here, we elucidate a selective and efficient transformation of a biomass-derived aldehyde (furfural) to the corresponding alcohol, promoted in compressed CO2 using a Pt/Al2O3 catalyst. Furfural contains a furan ring with C[double bond, length as m-dash]C and an aldehyde group, and is extremely reactive in a hydrogen atmosphere, resulting in several by-products and a threat to alcohol selectivity as well as catalyst life. The process described has a very high reaction rate (6000 h-1) with an excellent selectivity/yield (99%) of alcohol, without any organic solvents or metal additives. This strategy has several key features over existing methodologies, such as reduced waste, and facile product separation and purification (reduced energy consumption). Combining the throughput of experimental observation and molecular dynamics simulation, indeed the high diffusivity of compressed CO2 controls the mobility of the compound, and eventually maintains the activity of the catalyst. Results are also compared for different solvents and solvent-less conditions. In particular, combination of an effective Pt catalyst with compressed CO2 provides an encouraging alternative solution for upgradation of biomass related platform molecules.

An efficient cleavage of the aryl ether C-O bond in supercritical carbon dioxide-water.

A simple and highly efficient Rh/C catalyzed route for the cleavage of the C-O bond of aromatic ether at 80 °C in the presence of 0.5 MPa of H2 in the scCO2-water medium is reported; CO2 pressure and water play a key role under the tested conditions.

Dynamic control of gold nanoparticle morphology in a microchannel flow reactor by glucose reduction in aqueous sodium hydroxide solution.

Continuous flow synthesis of gold nanoparticles was demonstrated using a microchannel reactor with glucose reduction in aqueous alkaline medium. Particle size, morphology, and visual/optical properties of the dispersion liquid were controlled dynamically by tuning of the rate of NaOH addition. Characteristic star-like nanoparticles formed spontaneously as a quasi-stable state, but they changed the morphology to round shape and showed spectral change over time.

Continuous process for fabrication of size controlled polyimide nanoparticles using microfluidic system.

A new strategy has been developed for continuous preparation of polyimide nanoparticles within 10 s of short residence time using a system combining a micromixer and a micro heat exchanger, where the particle size can be controlled proportionally simply by varying the concentration of poly(amic acid) (PAA).

Preparation of silica sphere with porous structure in supercritical carbon dioxide.

Silica sphere with porous structure has been synthesized in supercritical carbon dioxide. The structure originates from a delicate CO(2) trapping phenomenon intended for void formation in the inorganic framework. Silicate polymerization and subsequent removal of CO(2) by depressurization leaves the porous architecture. The key factor to obtain stable porous spherical structure was CO(2) pressure. Different characterization techniques such as X-ray diffraction, scanning and transmission electron microscopy and N(2) adsorption-desorption isotherm were used to determine the framework structure, morphology and porosity of the material. Microscopic visualization of calcined material suggested that the spherical structure was consisted of macroporous windows of diameter approximately 100 nm and the space between macropores presents a wormhole like mesoporous/microporous structure. The pore diameter of the mesoporous structure has been calculated as approximately 3 nm. X-ray diffraction and N(2) adsorption isotherm analysis confirmed the presence of micropores and also the macropores. In addition, the resulting material possess high thermal and hydrothermal stability associated with fully SiO(4) cross-linking. The spherical structure with different types of porosity was successfully obtained without using any molding agent.

Introducing porosity into polyimide nanoparticles.

Novel porous polyimides (PIs) having diameters of several hundred nanometers have been fabricated successfully from precursor poly(amic acid) (PAA) derivatives with poly(acrylic acid) (PAS) as the porogen, using a reprecipitation method and subsequent imidization. The superficial high porosity with deep pores was introduced when using a more compatible combination of PAA and the porogen, i.e., PI (BPDA-PDA) and PAS rather than PI (10FEDA-4FMPD and PAS); the pore sizes ranged from 20 to 100 nm. The resulting porous PI nanoparticles had thermally stabilities (determined from their 5% weight loss temperatures at 400 degrees C) similar to those of corresponding PI nanoparticles lacking porous structures. Microphase separation within the PAA nanoparticles after reprecipitation induced the porous surface structure, the properties of which were influenced by the molecular weight of PAS and the chemical structure of PAA. These unique porous PI nanoparticles have great potential for application as low-k materials in next-generation technologies.