Improved On-Site Characterization of Arsenic in Gypsum from Waste Plasterboards Using Smart Devices

The impurities in waste plasterboards, a product of ethical demolition, are a serious problem for their recycling. Plasterboards, the wall materials used in old buildings, are often recycled into gypsum powder for various applications, including ground stabilization. However, this powder contains various chemical impurities from the original production process of the gypsum itself, and such impurities pose a risk of polluting the surrounding soil. Here, we present a simple method for verifying the presence of arsenic, a harmful element in recycled gypsum that is suitable for use at demolition sites. First, we developed a simple pretreatment method using a cation-exchange resin to dissolve insoluble gypsum suspended in water by exploiting a chemical equilibrium shift, and we estimated the quantity suitable for releasing the arsenic from arsenic-containing gypsum. This pretreated solution could then be tested with a conventional arsenic test kit by observing the color changes in the test paper using the image sensor of a smart device. This simple method could determine a wide range of arsenic quantities in the gypsum, which would be helpful for monitoring arsenic in recycled gypsum powder, thereby supporting the development of a safe circular economy for waste plasterboards

Dearomatization of 3-cyanoindoles by (3 + 2) cycloaddition: from batch to flow chemistry

International audience1,3-Dipolar dearomatizing cycloadditions between a non-stabilized azomethine ylide and 3-cyanoindoles or benzofuran afford the corresponding 3D-heterocycles bearing a quaternary carbon centre at the ring junction. While 6 equivalents of ylide precursor 1 are required for full conversion in a classical flask, working under flow conditions limits the excess (3 equiv., tR = 1 min) and leads to a cleaner process, affording cycloadducts that are easier to isolate

Catalytic Method for the Synthesis of C–N-Linked Bi(heteroaryl)s Using Heteroaryl Ethers and <i>N</i>‑Benzoyl Heteroarenes

C–N-linked bi­(heteroaryl)­s are synthesized by a rhodium-catalyzed <i>N</i>-heteroarylation reaction of <i>N</i>-benzoyl heteroarenes including azoles/azolones, pyridones, cyclic ureas, and cyclic imides using heteroaryl aryl ethers. The reaction involves the covalent bond-exchange reaction of N–CO and HetAr–O bonds without using metal bases and exhibits a broad applicability, giving diverse C–N-linked bi­(heteroaryl)­s containing five- and six-membered heteroarenes. The <i>N</i>-heteroarylation of N–H azoles/azolones and pyridone proceeds at higher reaction temperatures

Rhodium-Catalyzed Synthesis of Unsymmetric Di(heteroaryl) Sulfides Using Heteroaryl Ethers and <i>S</i>‑Heteroaryl Thioesters via Heteroarylthio Exchange

Unsymmetric di­(heteroaryl) sulfides were synthesized by a rhodium-catalyzed heteroarylthio exchange reaction of heteroaryl aryl ethers and <i>S</i>-(heteroaryl) thioesters. The reaction has broad applicability, giving diverse unsymmetric di­(heteroaryl) sulfides containing five- and six-membered heteroarenes. No base is required in this reaction, which has been developed by the judicious design of organic substrates

Rhodium-Catalyzed Synthesis of Unsymmetric Di(heteroaryl) Sulfides Using Heteroaryl Ethers and <i>S</i>‑Heteroaryl Thioesters via Heteroarylthio Exchange

Unsymmetric di­(heteroaryl) sulfides were synthesized by a rhodium-catalyzed heteroarylthio exchange reaction of heteroaryl aryl ethers and <i>S</i>-(heteroaryl) thioesters. The reaction has broad applicability, giving diverse unsymmetric di­(heteroaryl) sulfides containing five- and six-membered heteroarenes. No base is required in this reaction, which has been developed by the judicious design of organic substrates