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Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Water targets are in some labelling chemistry not the best choice. An alternative production route is to use neon gas, 20Ne(d,α)18F. Adding fluorine-19 gas to the neon as carrier will yield 18F2 that can be used for electrophilic substitution. However, adding carrier will lower the specific radioactivity of the labelled product.
Synthesis of copper(II) halide dimers with 2-amino-5-methylpyridine and serendipitous copper catalyzed synthesis of 3-bromo-2-ethyl-5-methyl-1H-pyrrolo[2,3-b]pyridine
Published in Journal of Coordination Chemistry, 2023
Carina L. Chittim, Kesli Faber, Diane A. Dickie, Christopher P. Landee, Shane G. Telfer, Mark M. Turnbull
The synthesis of the brominated pyrollopyridine ligand, however, has not been previously reported. We suggest the following sequence of steps as the mechanism (Scheme 4). First, Br2 is generated by air oxidation of bromide (likely also copper catalyzed), which has been invoked previously in the synthesis of (2-amino-3-methylpyridinium) (2-amino-5-bromo-3-methylpyridinium) tetrabromidocuprate(II) [45]. The bromine can react with the solvent to produce 1,1-dibromo-2-butanone which serves as the electrophile for an electrophilic substitution on the electron-rich 5MAP ring. The substitution occurs adjacent to the ortho/para directing, electron-donating amino substituent as expected. Equivalently, the 2-butanone could be mono-brominated, substitute the ring and then be further brominated (the benzylic position being additionally activated by the adjacent carbonyl group). Ring closure by imine formation is straightforward (with the Cu(II) ions acting as a Lewis acid catalyst), followed by the favorable tautomerization of a proton to generate the aromatic pyrrole ring. Proton transfer between the nitrogen atoms should be facile and the pyrrole nitrogen atom coordinates to the copper acetate to generate 3.
Preparation of macroporous ion-exchange resin organic amine composite material by using waste plastics and its application in CO2 capture
Published in Environmental Technology, 2023
Xinmin Liu, Yanjie Niu, Yuqing Huang, Xuexia Qiu, Qingjie Guo
Optimised structures of the electrostatic potential are shown in Figure 8. The red and blue colours indicate the negative and positive regions, respectively. The darker the colour, the greater the absolute value of the electrostatic potential. In the electrostatic potential diagram of polybutadiene-polystyrene, the H atom of meta position on the benzene ring is darker red, and the negative electrostatic potential is larger. The more susceptible to attack by the electrophile, the electrophilic substitution reaction occurs, and MCER was prepared. In the MCER electrostatic potential diagram, the –SO3Na of MCER has a strong positive potential and is vulnerable to the attack group with negative potential. The electron energy of MCER-DEA is calculated to be 1.14 ev (1 ev=96.5 kJ/mol) by formula 2, indicating that MCER formed an acid–base coordination with DEA, and MCER-DEA was prepared.
Catalytic ozonation of dibutyl phthalate in the presence of Ag-doped NiFe2O4 and its mechanism
Published in Environmental Technology, 2021
Di Zheng, Jiashun Cao, Peifang Wang, Junyu Zhao, Yujie Zhao, Teng Zhang, Chao Li
Based on the intermediates produced during catalytic ozonation process, the proposed pathway of DBP degradation in catalytic ozonation process is presented in Figure 9. Firstly, DBP occurred due to an electrophilic substitution reaction, and one hydrogen atom at the end of the benzene ring branch was substituted by hydroxyl to form an alcohol. Subsequently, ·OH was substituted by a substitution reaction to form a long chain of a benzene ring branch to form phthalic acid. Because phthalic acid has a relatively stable structure, it is difficult to further degrade under the attack of ozone molecules, and the strong oxidizing property of ·OH can open the phthalic acid and further form a carboxylic acid with a simple structure, such as oxalic acid. Acidic organic compounds were eventually mineralized to CO2 and H2O.