A Chemist from RUDN University Developed an Environmentally Friendly Method for Anti-Malaria and Anti-Leprosy Drug Production
Dapsone or diaminophenyl sulphone consists of two benzene rings with NH2 amino groups. The rings are connected with an oxidized atom of sulfur, or an SO2 group. To obtain dapsone, manufacturers oxidize its precursor in which the bond between the rings is formed by an SH group (sulfur and hydrogen). However, oxidation can also affect sensitive amino groups. Therefore, they have to be protected before the reaction starts—for example, by attaching special protective groups to them. The researcher from RUDN University developed a catalyst that provides for the oxidation of SH groups in the precursor with simple hydrogen peroxide. Hydrogen peroxide is considered the most environmentally friendly oxidizing agent because its only by-product is water. The reaction of oxidation takes place at room temperature, has only one stage, and requires no protection of amino groups.
“None of the earlier dapsone synthesis reactions can be called completely environmentally friendly as they happen in rigid conditions and have several stages: adding protective groups, synthesis, and their removal. This complexity increases the chances of by-products that should be removed from the reaction,” said Raphael Luke, Ph.D., the head of the Molecular Design and Synthesis of Innovative Compounds for Medicine Science Center at RUDN University.
His team developed a wolfram-based catalyst from polyoxometalates by replacing certain wolfram atoms with vanadium. This increased the acidic properties of the catalyst and sped up the reaction, allowing it to take place even at low temperatures. To prevent the catalyst from being washed off from the reaction, the chemists encased the new compound in a porous material—a hydrogel made of propanoic acid and acrylamide. Thanks to it, the catalyst can be re-used at least three times without losing its efficiency. The team also identified the most optimal synthesis conditions and reagent concentration and managed to reach 100% oxidation of the dapsone precursor at 25℃ in only nine hours.
The results of the work were published in the Microporous and Mesoporous Materials journal.
RUDN University mathematician together with colleagues from India and France for the first time studied in detail the system of coexistence of three species of living creatures in the wild. The results help to understand what parameters determine the extinction andли survivalof species, and how the number of species changes in space and time.
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