Synthesis of pH indicators for Cerenkov imaging by electrophilic substitution of bromine by fluorine in an aromatic system.

Autor: Kachur AV; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.; Department of Chemistry and Biochemistry, Misher College of Arts and Sciences, University of the Sciences, Philadelphia, PA 19104., Arroyo AD; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA., Bryan NW; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA., Saylor SJ; Department of Chemistry and Biochemistry, Misher College of Arts and Sciences, University of the Sciences, Philadelphia, PA 19104., Popov AV; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA., Delikatny EJ; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Jazyk: angličtina
Zdroj: Journal of fluorine chemistry [J Fluor Chem] 2017 Aug; Vol. 200, pp. 146-152. Date of Electronic Publication: 2017 Jul 05.
DOI: 10.1016/j.jfluchem.2017.06.017
Abstrakt: 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 revealed intermolecular attenuate Cerenkov radiation selectively near their maximum absorbance in a pH dependent manner.
Databáze: MEDLINE
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