Synthesis of pH indicators for Cerenkov imaging by electrophilic substitution of bromine by fluorine in an aromatic system
| Autor: | Alexander V. Kachur, E. James Delikatny, Anatoliy V. Popov, Alejandro D. Arroyo, Sarah J. Saylor, Nikaela W. Bryan |
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| Rok vydání: | 2017 |
| Předmět: |
Substitution reaction
010405 organic chemistry Organic Chemistry Electrophilic fluorination chemistry.chemical_element Thymol blue Nuclear magnetic resonance spectroscopy 010402 general chemistry Photochemistry 01 natural sciences Biochemistry Article 0104 chemical sciences Inorganic Chemistry chemistry.chemical_compound Electrophilic substitution chemistry Bromothymol blue Nucleophilic substitution Fluorine Environmental Chemistry Physical and Theoretical Chemistry |
| Zdroj: | Journal of Fluorine Chemistry. 200:146-152 |
| ISSN: | 0022-1139 |
| DOI: | 10.1016/j.jfluchem.2017.06.017 |
| Popis: | Direct electrophilic fluorination using molecular fluorine gas is used in organic synthesis to create novel fluorine-containing compounds with potential beneficial activity that could not be obtained by nucleophilic substitution. In this paper, we report a novel electrophilic substitution of bromine by fluorine in an aromatic system. The mechanism of this type of fluorination was explored using the reaction between bromothymolsulfonphthalein (Bromothymol Blue) and dilute fluorine gas under acidic conditions. Substitution occurs in the bromine atoms located in the ortho-position relative to the hydroxyl group. A similar electrophilic fluorination of thymolsulfonphthalein (Thymol Blue) leads to a substitution of hydrogen atoms in the same position (ortho to hydroxyl). NMR spectroscopy was used to confirm the fluorination sites. NMR spectra of thymolsulfonphthalein and its derivatives under basic conditions can be explained by considering the absence of resonance between the two phenolic rings. Both dibromothymol blue and fluorobromothymol blue intermolecularly attenuate Cerenkov radiation selectively near their maximum absorbance in a pH dependent manner. |
| Databáze: | OpenAIRE |
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