Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
19F NMR spectra of mono- (a) and di- (c) fluorophenolphthalein show that all the signals have a chemical shift close to δ −138 ppm, which is specific for fluorine atoms in ortho position to hydroxyl group of the phenolic rings. Decoupling of the hydrogen-fluorine coupling (b and d, respectively) indicates that for both compounds no isomers are present and both fluorine atoms in difluorophenolphthalein molecule are identical.
