The role of fluorination

Description

The introduction of fluorine into organic molecules uniquely affects the properties of the derived compounds due to the atom's small size, which is comparable to hydrogen, high electronegativity, and the strong nature of the resulting C–F bond. Incorporating fluorine into bioactive molecules for pharmaceutical and agrochemical applications often adds desirable properties, such as:

Increased lipophilicity

Enhanced bioavailability

Improved metabolic stability

Additionally, late-stage 18F labeling has received increased attention in the context of clinical PET imaging.

Fluorination treatment

Fluorination treatment is a surface modification method using which a desired surface structure of a certain hydrogen storage alloy can be constructed according to the requirements for practical use[1]. The hydrogenation and dehydrogenation performances of the hydrogen storage alloys in gas–solid reactions or alkaline electrolytes can be improved by surface modification through fluorination treatments. It is necessary to point out that the fluorination treatments are not omnipotent. They can only resolve the kinetic problems related to the alloy surface but cannot improve the thermodynamic properties of the hydrogen storage alloys. A proper selection of the treatment solution and treatment method and the treatment conditions is essential to obtain the desired treatment effects.

Property Control of Carbon Materials by Fluorination

Fluorination is effective in chemically modifying and controlling the physicochemical properties of carbon materials over a wide range, creating opportunities to prepare carbon alloys with new functionalities[2]. Carbon alloyed nanotubes were prepared by selective fluorination of hidden surfaces of multi-wall carbon nanotubes using a template carbonization technique. Carbon–fluorine bonds are formed on the hidden surfaces of the tubes, while internal surfaces retain their sp2-hybridization. Fluorination (as a form of carbon-alloying) significantly affects such properties of hidden surface extents of nitrogen adsorption, hysteresis loops, and pore size distributions. Fluorination enhanced the coulomb efficiency of Li/carbon nanotube rechargeable cells in an aprotic medium (with reversible lithium insertion in hidden surfaces) as studied by galvanostatic discharge-charge experiments.

Fluorinated drugs

Currently, amongst the drugs available in the market, more than 30% are fluorinated drugs. Incorporation of the fluorine atom in the organic framework is known to alter their properties, such as solubility, metabolic stability, and bioavailability. Due to these unique properties, fluorinated compounds have received high attention in chemistry, especially in the pharmaceutical and agrochemical industries. Also, the 18F radioisotopes of fluorine are extensively used in nuclear medicine and radiopharmaceutical chemistry. A number of fluorine-containing e imidazo[1,2-a] pyridine scaffold drugs available in markets show better pharmaceutical properties than the parent molecules. 1-fluoropyridinium tetrafluoroborate could be used as a fluorinating reagent[3]. A one-pot synthesis of C-3 fluorinated imidazopyridines (F-IMPY) is reported under additive-free conditions from commercially available styrene and 1-fluoropyridinium tetrafluoroborate as a fluorine source. The substrate styrene undergoes keto-bromination/condensation/fluorination transformation in three sequential steps to furnish F-IMPY.

References

[1] Li, Z. P. and S. Begum. “Hydrogen–Metal Systems: Fluorinated Metal Hydrides.” 2001: 3941-3953.

[2] H Touhara, F Okino. “Property control of carbon materials by fluorination.” Carbon 38 2 (2000): Pages 241-267.

[3] Madhukar S. Said . “Regioselective One‐Pot Synthesis of 3‐Fluoro‐Imidazo[1,2‐a]pyridines from Styrene.” Asian Journal of Organic Chemistry 8 11 (2019): Pages 2143-2148.