Improved Process for the Continuous Acylation of 1,3-Benzodioxole.

The acylation of 1,3-benzodioxole was studied in a continuous process using a recyclable heterogeneous substoichiometric catalyst. In a short time period (30 min), at 100 °C, the conversion rate was 73%, with a selectivity of 62% of the desired acylated product; the reaction was run continuously for 6 h, showing excellent stability and selectivity. Moreover, the unreacted starting material, 1,3-benzodioxole, can be easily separated by distillation and recycled.

Bio- and Biomimetic Receptors for Electrochemical Sensing of Heavy Metal Ions.

Heavy metals ions (HMI), if not properly handled, used and disposed, are a hazard for the ecosystem and pose serious risks for human health. They are counted among the most common environmental pollutants, mainly originating from anthropogenic sources, such as agricultural, industrial and/or domestic effluents, atmospheric emissions, etc. To face this issue, it is necessary not only to determine the origin, distribution and the concentration of HMI but also to rapidly (possibly in real-time) monitor their concentration levels in situ. Therefore, portable, low-cost and high performing analytical tools are urgently needed. Even though in the last decades many analytical tools and methodologies have been designed to this aim, there are still several open challenges. Compared with the traditional analytical techniques, such as atomic absorption/emission spectroscopy, inductively coupled plasma mass spectrometry and/or high-performance liquid chromatography coupled with electrochemical or UV-VIS detectors, bio- and biomimetic electrochemical sensors provide high sensitivity, selectivity and rapid responses within portable and user-friendly devices. In this review, the advances in HMI sensing in the last five years (2016-2020) are addressed. Key examples of bio and biomimetic electrochemical, impedimetric and electrochemiluminescence-based sensors for Hg2+, Cu2+, Pb2+, Cd2+, Cr6+, Zn2+ and Tl+ are described and discussed.

Oxygen as redox mediator in scanning electrochemical microscopy. Application to the study of localised acid attack of marble.

Oxygen from air-saturated aqueous solutions was employed as redox mediator in SECM experiments. Accurate approach curves under negative-feedback conditions were obtained using platinum and gold microelectrodes. Imaging experiments were also carried out, using a 2.5 microns gold microelectrode and oxygen that acted as distance mediator. The topographic images of a glass surface and that of a marble surface prior and after localised acid attack were recorded. High concentrations of hydrogen ions were produced locally, at the microelectrode tip held 3 microns above the marble surface, by applying a large enough positive potential within the oxygen evolution region. Under these conditions, the dissolution of CaCO3 occurred. Pits were produced, and the crater volumes thus obtained were linearly dependent on the electrolysis time.