F number (chemistry)
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F number is a correlation number used in the analysis of polycyclic aromatic hydrocarbons (PAHs) as a descriptor of their hydrophobicity and molecular size.[1] It was proposed by Robert Hurtubise and co-workers in 1977.[2]
Example
The F number is calculated using the formula:
where:
- B2 is the number of double bonds
- C12 is the number of primary carbon and secondary carbon atoms
- R is the number of non-aromatic rings.
For fluorene, there are 6 apparent double bonds (three pi bonds in each side benzene-like ring); the central ring has one secondary carbon and is non-aromatic. Therefore:
