Palladium-Catalyzed One-Pot Diarylamine Formation from Nitroarenes and Cyclohexanones

The first palladium-catalyzed diarylamine formation from nitroarenes and cyclohexanone derivatives using borrowed hydrogen is described. Various diarylamines were selectively obtained in good to excellent yields. The reaction tolerated a wide range of functionalities. The nitro reduction, cyclohexanone dehydrogenation, and imine formation and reduction were realized in a cascade without an external reducing reagent and oxidant

Four-Component Approach to <i>N</i>‑Substituted Phenothiazines under Transition-Metal-Free Conditions

An efficient synthesis of <i>N</i>-substituted phenothiazines has been developed from readily available amines, cyclohexanones, and elemental sulfur. The combination use of KI/DMSO in an oxygen atmosphere significantly improved the reaction yields

Citric Acid as Green Modifier for Tuned Hydrophilicity of Surface Modified Cellulose and Lignin Nanoparticles

This paper proposes one straightforward route for citric acid modification of two different lignocellulosic products, cellulose nanocrystals (CNC) and lignin nanoparticles (LNP). Modified cellulose nanocrystals (MCNC) and lignin nanoparticles (MLNP) were characterized by means of Fourier Transform Infrared Spectroscopy (FT-IR), ¹³C and ¹H nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible/near-infrared (UV–vis/NIR) spectrometry and thermogravimetric analysis (TGA). The reaction mechanism between citric acid and both CNC and LNP was discussed. The resultant MCNC exhibited improved dispersion in polar solvents, better thermal stability as compared with CNC while, in the case of LNP, a slight increase in thermal stability and alteration of MLNP dispersibility in polar solvents were proved. These results confirmed how esterified (MCNC) and etherified (MLNP) biobased nanoparticles with tuned hydrophilicity, obtained by a treatment with a low cost, sustainable and easily soluble cross-linker, have potential for widespread applicability in the field of polymeric based nanocomposites having different polarity

High-Performance Wet Adhesion of Wood with Chitosan

Strong adhesion is desirable when using wood with a wide range of moisture contents, but most of the existing adhesives face challenges in bonding wood under high-humidity conditions. Here, we report a simple strategy that involves the one-step dissolution of chitosan powder in acetic acid at room temperature, followed by direct use of the resulting chitosan slurry as an adhesive on dry/wet wood veneers. Mechanical interlocks and hydrogen bonds at cell wall interfaces provided strong adhesion. Moreover, heat treatment induced recrystallization and cross-linking of chitosan chains, resulting in a high cohesion. Meanwhile, heat treatment caused the acetylation reaction between the protonated amino groups (NH3+) of chitosan and acetate groups (CH3COO–) to produce hydrophobic acetyl groups. In addition, we prepared wooden products such as plywood (dry veneers) and wooden straws (wet veneers) using wood veneers with different moisture contents. The tensile shear strengths under 63 °C water and under boiling water of plywood were 1.12 and 0.81 MPa, respectively. The compressive strength of wooden straws is up to 35.32 MPa, which was higher than that of existing commercial straws (such as paper straws, polypropylene straws, and plastic straws). The chitosan wet adhesive showed good water resistance, high bonding strength, environmental degradability, and nontoxicity, thus providing a highly promising alternative to traditional wood composite adhesives