Efficient Solvent‐Free Synthesis of Sucrose Esters via Sand‐Milling Pretreatment on Solid–Liquid Mixtures

Assessing the reinforced molecular/mechanical behaviors of GOs@Mo-MOFs films deposited via electrophoresis onto microdevices: Experimental and theoretical perspectives

One of the primary hurdles in microdevice fabrication lies in ascertaining the most impactful tactics for adapting metal surfaces. Through a one-pot tackle and distinct mechanochemical reactions evoked by 15 min aqueous wet sand-milling (SM-15), we successfully grafted Mo-based metal-organic frameworks (Mo-MOFs) onto graphene oxides (GOs). Following this, a convenient and readily scalable methodology of electrophoretic deposition was implemented to create controllable thickness of SM-15 GOs@Mo-MOFs lubricating films, achieving considerable enhancements of 143% and 91% in hardness and Young's modulus, respectively, when compared to those of SM-15 Mo-MOFs. The successful synthesis of SM-15 GOs@Mo-MOFs was corroborated using strategies such as x-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy. Analyses using the micro-tribotester indicated that the new film exhibited a lowest friction coefficient of roughly 0.5 when imposed with a load of 5 N and sliding speed of 8 mm/s. In addition, the optical profiler nano-indentation in situ scanning probe microscope revealed that SM-15 GOs@Mo-MOFs films had smaller and shallower scratches and grooves compared to SM-15 Mo-MOFs ones. The calculated results of key descriptors (EHOMO, ELUMO, ΔE, etc.) in density functional theory quantitatively disclosed the interaction mechanisms between GOs@Mo-MOFs molecules and microdevices. We first scrutinized the innate properties of molecule adsorption energy and frictional mechanical behaviors using synergetic cross-scale simulations, such as Monte Carlo and finite element methods. The expectation was that this process would motivate a valuable technique for shielding in the thriving micromanufacturing.

Solvent-Free Approaches in Carbohydrate Synthetic Chemistry: Role of Catalysis in Reactivity and Selectivity

Owing to their abundance in biomass and availability at a low cost, carbohydrates are very useful precursors for products of interest in a broad range of scientific applications. For example, they can be either converted into basic chemicals or used as chiral precursors for the synthesis of potentially bioactive molecules, even including nonsaccharide targets; in addition, there is also a broad interest toward the potential of synthetic sugar-containing structures in the field of functional materials. Synthetic elaboration of carbohydrates, in both the selective modification of functional groups and the assembly of oligomeric structures, is not trivial and often entails experimentally demanding approaches practiced by specialized groups. Over the last years, a large number of solvent-free synthetic methods have appeared in the literature, often being endowed with several advantages such as greenness, experimental simplicity, and a larger scope than analogous reactions in solution. Most of these methods are catalytically promoted, and the catalyst often plays a key role in the selectivity associated with the process. This review aims to describe the significant recent contributions in the solvent-free synthetic chemistry of carbohydrates, devoting a special critical focus on both the mechanistic role of the catalysts employed and the differences evidenced so far with corresponding methods in solution.

Controlling reaction selectivity for sugar fatty acid ester synthesis by using resins with different basicities

A strongly basic ion-exchange resin catalyst was reported to exhibit a high catalytic activity in transesterification to produce a bio-based surfactant, sugar ester under mild condition. However, the side-reactions to decompose the reactant and the product were found to occur. This study was aimed to improve the selectivity of sugar ester synthesis by newly focusing on the basicity of the resin. A weakly basic resin (Diaion WA20) with a lower mass transfer resistance suppressed the decompositions while maintaining synthesis rate. Controlling molar ratio of the reactants in the intraparticle reaction field also increased the reaction selectivity, 72.1% and product yield, 57.5%. Both values were drastically increased compared to the reported values with the strongly basic resin (selectivity 50.9%, yield 14.3%). This is the first knowledge to show a high catalytic activity of weakly basic resin. These results suggest that a more efficient continuous production process would be possible.