Fluorenol or 9-hydroxyfluorene (CAS #1689-64-1) is not a recently discovered molecule. It was patented in 1939 as an insecticide. It can oxidize to fluorenone and fluorenone group is present in Tilorone (an antiviral prescription medicine) and mitochondrial dyes. In rats, fluorenol was detected as a carrier of eugeroic properties in a study that examined the fate of non-toxic currently patented eugeroic substances [1]. Specific eugeroic substances should have activity that is limited to promoting wakefulness without altering mood, impairing cognition or causing addiction. Theoretically, fluorenol fills these criteria well (it has still some [2] but even lower dopaminergic properties related to addiction and scheduling by regulatory agencies and even higher wakefulness-promoting histaminergic activities than prescription eugeroics and is not a substrate of P450) but there have been no human studies, including these of safety. For example, fluorenone, while lacking bacterial mutagen properties, exhibited antiandrogenic and mitochondrial membrane disrupting properties inquantitative high-throughput screening at 0.5 nanomole concentration [3]. Taking into consideration that fluorene or fluorenol are metabolites of -afinil drugs, it may explain some effects that oppose testosterone in rats [4]. While pharmaceutical research of systemically administrated substances is concerned with nanomolar concentrations, it is known that in millimolar concentration fluorenol shows cytotoxic phototoxicity [5], suggesting it may add to other photosensitizers or cause lower-level phototoxicity by itself. Nevertheless, appears that self-experimenters have discussed the effects of ‘hydrafinil’ with questionable safety online. There has been at least one precedent of private phototoxicity in lower concentrations. There has been at least one precedent of private sector not pursuing reasearching fluorenol further [6], and it has been hypothesized that the private enterprise lost interest due to anticipated issue with ability to patent the substance and, possibly, environmental issues.

[1] https://www.ncbi.nlm.nih.gov/pubmed/22546675
[2] https://pubchem.ncbi.nlm.nih.gov/compound/74318#section=Biological-Test-Results
[3] https://pubchem.ncbi.nlm.nih.gov/compound/9-Fluorenone#section=BioAssay-Results
[4] http://www.revistafarmacia.ro/201702/art-19-Belaran_Karimian_275-283.pdf
[5] https://eurekamag.com/pdf/008/008414345.pdf
[6] https://mentalhealthdaily.com/2015/12/23/hydrafinil-fluorenol-a-modafinil-analogue-with-questionable-safety/