:F number (chemistry)

The F number is calculated using the formula:

:$F\; =\; B\_2\; +\; C\_\{12\}\; -\; \backslash frac\{1\}\{2\}R$

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.

Image:Fluorene.png

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:

:$F\; =\; 6\; +\; 1\; -\; \backslash frac\{1\}\{2\}1\; =\; 6.5$

{{clear}}

It has been found that the F number linearly correlates with the log k' value (logarithm of the retention factor) in aqueous reversed-phase liquid chromatography. This relationship can be used to understand the significance of different aspects of molecular architecture on their separation using different stationary phases.{{cite journal |last1= Jinno |first1= Kiyokatsu |last2= Okamoto |first2= Mitsuyoshi |journal= Chromatographia |year= 1984 |volume= 18 |issue= 1 |pages= 44–46 |title= Correlation of the retention data of polyaromatic hydrocarbons obtained on various stationary phases used in normal- and reversed-phase liquid chromatography |doi= 10.1007/BF02279465 |s2cid= 54035024 }} This size analysis is complementary to the length-to-breadth (L/B) ratio, which classifies molecules according to their "rodlike" or "squarelike" shape.{{cite journal |title= Molecular Shape Selectivity through Multiple Carbonyl−π Interactions with Noncrystalline Solid Phase for RP-HPLC |first1= M. Mizanur |last1= Rahman |first2= Makoto |last2= Takafuji |first3= Hamid R. |last3= Ansarian |first4= Hirotaka |last4= Ihara |journal= Anal. Chem. |year= 2005 |volume= 77 |issue= 20 |pages= 6671–6681 |doi= 10.1021/ac050851v |pmid= 16223255 }}

{{reflist}}

• [https://web.archive.org/web/20070701131442/http://chrom.tutms.tut.ac.jp/JINNO/DATABASE/00fnumber.html List of F numbers for PAHs]

Category:Polycyclic aromatic hydrocarbons

Category:Chromatography

{{chromatography-stub}}