Polyethylenimines as Homogeneous and Heterogeneous Catalysts for Glucose Isomerization

This study investigated polyethylenimines (PEIs) with varied architectures as low toxicity and efficient catalysts for aqueous isomerization of glucose to fructose. Under the investigated reaction conditions, the studied PEIs achieved 33–36% maximum fructose yields with 66–77% selectivity at 110–120 °C, with the branched PEI generally outperforming the linear and comb PEIs. Moreover, with 1 wt % sodium chloride, the PEIs achieved 35–38% maximum fructose yields with 61–72% selectivity at 110 °C. After modification through room temperature cross-linking, the branched PEI was transformed into a recyclable heterogeneous catalyst with similar isomerization performance (30% fructose yield and 78% fructose selectivity at 120 °C) to the homogeneous PEIs. Remarkably, in the presence of neutral salts, the heterogeneous PEI achieved an approximately 41% fructose yield with 72–78% selectivity at 110 °C and showed an excellent reusability

Highly Efficient and Divergent Construction of Chiral γ‑Phosphono-α-Amino Acids via Palladium-Catalyzed Alkylation of Unactivated C(sp³)–H Bonds

Chiral γ-phosphono-α-amino acids play a crucial role in inhibitors of natural enzymes, as well as agonists and antagonists of metabotropic glutamate receptors. In this paper, an efficient and general protocol for the construction of chiral γ-phosphono-α-amino acids via Pd-catalyzed AQ-directed C­(sp³)–H alkylation of α-amino acid derivatives is developed. The reaction shows reactivity between methylene C­(sp³)–H bonds with phosphonated alkyl iodides with high yields, enantioselectivity, and diastereomeric ratios, which enables access to a wide range of challenging and important γ-phosphono-α-amino acids in large scale. Meanwhile, δ-phosphono-α-amino acid and δ-phosphono-propionic acid derivatives can also be successfully obtained. The derivatization reaction in the synthesis of l-AP4 and l-phosphinothricin highlight the applicability of this method

Scalable Sn-Catalyzed Regioselective Allylation of 1‑Methyl‑l‑α-rhamnopyranoside

A robust selective allylation of 1-methyl-l-α-rhamnose was developed using di-<i>n</i>-butyltin oxide (<i>n</i>-Bu₂SnO) as the catalyst. Proton sponge was found to be the optimal base for high regioselective control. The optimized condition afforded the 3-<i>O</i>-allylated rhamnose in excellent regioselectivity (>20:1) and 82% isolated yield on a 50 g scale. A scalable isolation/purification process was developed which afforded the desired product in 72% yield with 1530 ppm of Sn. The residual Sn level can be further reduced to <20 ppm by treatment with scavengers. This catalytic system also showed outstanding potential in the selective benzylation of the same substrate

Basic Amino Acids as Green Catalysts for Isomerization of Glucose to Fructose in Water

Fructose is not only an important food and beverage ingredients, but also a renewable resource for production of 5-hydroxymethylfurfural. This study investigated nontoxic basic amino acids (arginine, lysine, and histidine) as isomerization catalysts to isomerize glucose to fructose in water. The results showed that arginine was the most effective isomerization catalyst with a 31% maximum fructose yield with 76% selectivity achieved under the investigated reaction conditions. A mechanistic study verified that the isomerization reaction catalyzed by arginine proceeded through an enediol intermediate, which formed after the deprotonation at C-2 position of acyclic glucose

Metal-Free, Efficient Oxyfluorination of Olefins for the Synthesis of α‑Fluoroketones

A novel oxyfluorination of olefin reactions has been developed. The reactions involve a metal-free and green catalytic system for the synthesis of α-fluoroketones which is an important building block for organic synthesis. Moreover, this reaction system exhibits great functional group tolerance

Monodispersed Bubble Generation Using Hydrophobic Orifices: The Extended Tate’s Law

The use of submerged orifices for bubble generation is ubiquitous in industries with wettability known to influence the bubble departure diameter. In this study, we investigated bubble generation and departure from the orifices (0.3–2 mm) drilled on hydrophobic perfluoroalkoxy (PFA) tubes in water. By varying the gas inflow rate (33 to 200 mL/min), we found that the Sauter mean diameter closely matched those generated by hydrophilic quartz orifices. However, monodispersed bubbles were formed on the PFA tube compared to those on quartz with much wider size distributions. By examining the dynamic bubbling process, we confirmed its agreement with Tate’s law, which was originally developed for quasi-steady conditions and emphasizes a balance between capillary and buoyancy forces. However, it should be noted that dynamic conditions lead to an increase in bubble volume compared to the quasi-steady condition despite following the same principle, which is explained by the continuous gas inflow when the bubble departs from the orifice at a necking stage. The above understandings enable generation of monodispersed bubbles under dynamic conditions, benefiting industries requiring precise control on bubble size, such as the bubble assisted wet etching and cleaning processes in semiconductor fabrication

Comparison with the extended TOPSIS of Yue.

<p>Comparison with the extended TOPSIS of Yue.</p

Ideal solutions.

<p>Ideal solutions.</p

A rough set approach for determining weights of decision makers in group decision making

<div><p>This study aims to present a novel approach for determining the weights of decision makers (DMs) based on rough group decision in multiple attribute group decision-making (MAGDM) problems. First, we construct a rough group decision matrix from all DMs’ decision matrixes on the basis of rough set theory. After that, we derive a positive ideal solution (PIS) founded on the average matrix of rough group decision, and negative ideal solutions (NISs) founded on the lower and upper limit matrixes of rough group decision. Then, we obtain the weight of each group member and priority order of alternatives by using relative closeness method, which depends on the distances from each individual group member’ decision to the PIS and NISs. Through comparisons with existing methods and an on-line business manager selection example, the proposed method show that it can provide more insights into the subjectivity and vagueness of DMs’ evaluations and selections.</p></div

Hierarchical structure of the proposed approach.

<p>Hierarchical structure of the proposed approach.</p