Extreme thermal stability of disodium 9-fluorenone dianion as a practical indicator for the preparation of absolute THF

Article abstract of DOI:10.1016/S0040-4039(99)01506-3

The fact that the lifetime of the disodium 9-fluorenone dianion is longer than that of the corresponding benzophenone dianion in refluxing THF for more than several months, which was proved by their ¹H NMR analyses and also by the isolated yields of their oxidation products (parent ketones), strongly suggests using 9-fluorenone as an excellent indicator for the preparation of absolute THF.