Recent advances in nitrene chemistry from acyclic precursors are reviewed in this paper. Early developments in nitrene chemistry predominantly focused on exploiting new nitrene precursors and inventing new types of nitrene-based transformations. Organic azides, iminoiodinanes (even in situ generated iminoiodinanes), amines, and amide N–O compounds have all been reported as efficient acyclic nitrene precursors. Nitrene-based transformations mainly include C–H amination/amidation, aziridination, addition to unsaturated bonds, sulfimidation, etc. In many cases, asymmetric versions of C–H amination/amidation, aziridination and sulfimidation have been demonstrated. In this review, a particular emphasis is placed on reactions of nitrene with unsaturated bonds and reactions using amide N–O compounds as nitrene precursors. It can be seen that the reactivity of nitrene species can be controlled by the metal centre, ligand, type of nitrene precursor, and reaction system.

Nowadays, the fast expansion of the economy and industry results in a considerable volume of wastewater being released, severely affecting water quality and the environment. It has a significant influence on the biological environment, both terrestrial and aquatic plant and animal life, and human health. Therefore, wastewater treatment is a global issue of great concern. Nanocellulose’s hydrophilicity, easy surface modification, rich functional groups, and biocompatibility make it a candidate material for the preparation of aerogels. The third generation of aerogel is a nanocellulose-based aerogel. It has unique advantages such as a high specific surface area, a three-dimensional structure, is biodegradable, has a low density, has high porosity, and is renewable. It has the opportunity to replace traditional adsorbents (activated carbon, activated zeolite, etc.). This paper reviews the fabrication of nanocellulose-based aerogels. The preparation process is divided into four main steps: the preparation of nanocellulose, gelation of nanocellulose, solvent replacement of nanocellulose wet gel, and drying of nanocellulose wet aerogel. Furthermore, the research progress of the application of nanocellulose-based aerogels in the adsorption of dyes, heavy metal ions, antibiotics, organic solvents, and oil-water separation is reviewed. Finally, the development prospects and future challenges of nanocellulose-based aerogels are discussed.