Alkyl Fluorinated Building Blocks
Alkyl fluorinated building blocks are a series of alkyl compounds substituted by fluorine atoms, which occur in a wide range of products. According to the number of fluorine substituents, they can be divided into monofluoro, polyfluoro and perfluorinated alkyl compounds. Current interest in fluorination chemistry is largely a consequence of the properties that fluorine substitution can impart on molecules, such as pharmaceuticals, agrochemicals, materials, and radiotracers for positron emission tomography. As many as 30-40% of agrochemicals and 20-25% of pharmaceuticals on the market are estimated to contain fluorine.
Fluorine is the most electronegative element and its properties can be distinctive in comparison to other organohalogens. The presence of a fluorine atom or a fluorinated group strongly affects the physical and chemical properties of a molecule such as chemical stability, biological activity and temperature resistance. The carbon-fluorine bond is one of the strongest in organic chemistry (an average bond energy around 480 kJ/mol), significantly stronger than the bonds of carbon with other halogens. Carbon-fluorine bond formation is a challenging chemical transformation largely due to fluorine’s high electronegativity and the high hydration energy of fluoride anion.