26 July 2019 Bulletin

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Phenanthrene

Phenanthrene, also known as phenanthrin, is a polycyclic aromatic hydrocarbon (PAH) with three aromatic rings derived from coal tar. It has a chemical formula of C14H10, a molecular weight of 178.22, and exists as a colourless to white crystalline substance with a bluish fluorescence. It has a melting point of 100°C, a boiling point of 340°C, a density of 1.179 at 25°C. Phenanthrene is almost insoluble in water (1-1.6 mg/L), but is soluble in glacial acetic acid and a number of organic solvents including ethanol, benzene, carbon disulfide, carbon tetrachloride, diethyl ether, and toluene. [1,2]

 


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Most powerful and mildest reagents obtained based on eco-friendly iodine

An international collaboration of chemists from Tomsk Polytechnic University, USA, Great Britain, Canada, Belgium, and France has developed a line of polyvalent iodine-based reagents for organic synthesis. This is an eco-friendly replacement of conventional reagents based on toxic compounds such as vanadium and nitrous oxide. The line includes both the most powerful reagent and the mildest one. They are promising for the synthesis of new polymers and in more extent for the pharmaceutical industry that uses reagents based on heavy metals in producing medications. As reported by the Press Office of the Ministry of Science and Higher Education of the Russian Federation, the latest results were published in the journal Chemical Communications of the Royal Society of Chemistry. Polyvalent iodine as proposed by TPU scientists and their foreign colleagues can replace toxic heavy and transition platinum metals in reagents. Compared to a normal state whereby iodine forms a bond with only one carbon atom in organic synthesis, in a polyvalent state it can form a bond with a few atoms, i.e. it becomes more active. Project supervisor Mekhman Yusubov, who is also TPU First Vice-Rector for Science, says, "Chemical Communications published a whole series of articles authored by scientists of our collaboration. Moreover, they were featured as an independent entry on Chemistry World of the Royal Society of Chemistry. To expand further prospects for applying reagents based on polyvalent iodine, we purposefully derived a whole line of reagents with different activity ranging from the mildest and most selective to the most powerful ones. In our opinion, they have an unmatched advantage that they are non-toxic when taken separately, do not produce harmful by-products and allow the reaction to take place under very simple conditions. If synthesis with common reagents needs high temperature of about 350-500 °C and therefore special conditions, polyvalent iodine makes it possible to work at room temperature." The mildest reagent in the series is called tosylate, a derivative of 2-iodoxybenzoic acid, and the most powerful is 2-iodoxybenzoic acid ditriflate. "It was a non-trivial challenge to synthesise them. In the first case, polyvalent iodine was combined with a triflate group, and in the second—with a tosylate group. This was difficult to do because these groups themselves are very powerful acids. When we managed to combine them with iodine, they became 'mild', they do not cause any side processes during the reaction," explains the scientist. As a result, the most powerful reagent allows the synthesis, for example, of fluorinated alcohols. They are widely used to obtain biologically active compounds that are the basis for perfluorinated polymers. Previously they could only be synthesised with the use of agents based on toxic vanadium oxide and nitric oxide. According to the authors, theoretically, it is possible to create an even more powerful reagent. The international collaboration will develop this direction as well. "The mildest reagent is suitable for oxidising natural compounds such as complex organic compounds which are part of living bodies. The reagent does not damage initial compounds nor does it cause any side processes. In addition, the entire reaction takes no more than 5 minutes at room temperature. This is a high rate for organic synthesis," notes Professor Mekhman Yusubov.

http://phys.org

 

Japan and UN Environment announce new efforts to prevent mercury tragedy

Japan’s Ministry of the Environment and the United Nations Environment Program recently announced a new project to protect the environment and human health from adverse impacts of mercury. Up to $3 million will be allotted to the project, which will help establish a regional mercury monitoring laboratory network in Asia and the Pacific and provide for capacity building and training for countries around the region. With its first-hand experience of Minamata disease, a serious illness caused by mercury poisoning and named after the Japanese city where it was first discovered, Japan has played a leading role in global mercury reduction. UN Environment Programme hosts the Minamata Convention on Mercury, a global treaty designed to safeguard the planet from the dangers of mercury. Dechen Tsering, UN Environment’s Regional Director for Asia and the Pacific, said, “The dangerous effects of mercury on the environment and human health are now well documented, and the global community is acting to protect people and planet. Japan has long been an important leader on this issue, and this new contribution only serves to underline their commitment.” Tamami Umeda, Director General for Environmental Health Department of the Ministry of the Environment Japan, said, “In the implementation of the Minamata Convention, we need effective and timely actions. We also need to bring wider stakeholders on board. With that in mind, Japan has launched the new project to enhance mercury monitoring as a basis for enhanced science-based policy-making in towards global mercury pollution.” Mercury is used in a wide variety of applications and finds its way into the environment through industrial emissions and channels like artisanal gold mining. From the environment, it can be accumulated by some species that are then eaten by humans – with health concerns for high risk populations. Approximately half of the global mercury consumption and emissions occur in Asia and the Pacific. In addition to the monitoring network and capacity building, the funding will also support the creation of a scientific database with information that governments and institutions can apply toward effective mercury management.

 

https://www.unenvironment.org

 

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