Fluorous
Encyclopedia
Fluorous chemistry is chemistry that uses perfluorinated compounds
, commonly the fluorosurfactant
perfluorooctanoic acid
(PFOA). Due to the extreme electronegativity
of fluorine
, perfluorinated compounds have unique physical properties which are useful in organic synthesis
and separation methods such as solid phase extraction
. In practice, a perfluorinated alkane
is often incorporated into an otherwise conventional organic reagent as an affinity tag
to facilitate recovery of a catalyst, reaction product, or reaction byproduct
. The rationale for using fluorous tags in synthesis or separation is the notion of the fluorous phase, a partitioning
modality distinct from polar
/non-polar or hydrophilic/hydrophobic. Although many fluorochemicals are known to have toxic effects, the high affinity of fluorous tags for fluorous phases or fluorous-derivatized solid phases allows for near complete recovery of the tagged reagent (i.e., near complete reduction in a chemical waste stream), making the use of fluorous chemistry techniques a popular topic in green chemistry
.
Perfluorinated compounds
A perfluorinated compound is an organofluorine compound with all hydrogens replaced by fluorine on a carbon chain—but the molecule also contains at least one different atom or functional group. Thus, PFCs have properties similar to fluorocarbons as they are fluorocarbon derivatives...
, commonly the fluorosurfactant
Fluorosurfactant
Fluorosurfactants, or fluorinated surfactants, are synthetic organofluorine chemical compounds that have multiple fluorine atoms. They can be polyfluorinated or fluorocarbon-based . As surfactants, they are more effective at lowering the surface tension of water than comparable hydrocarbon...
perfluorooctanoic acid
Perfluorooctanoic acid
Perfluorooctanoic acid , also known as C8 and perfluorooctanoate, is a synthetic, stable perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as a surfactant in the emulsion polymerization of fluoropolymers. It has been used in the manufacture of such prominent...
(PFOA). Due to the extreme electronegativity
Electronegativity
Electronegativity, symbol χ , is a chemical property that describes the tendency of an atom or a functional group to attract electrons towards itself. An atom's electronegativity is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus...
of fluorine
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...
, perfluorinated compounds have unique physical properties which are useful in organic synthesis
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
and separation methods such as solid phase extraction
Solid phase extraction
Solid-phase extraction is a separation process by which compounds that are dissolved or suspended in a liquid mixture are separated from other compounds in the mixture according to their physical and chemical properties. Analytical laboratories use solid phase extraction to concentrate and purify...
. In practice, a perfluorinated alkane
Alkane
Alkanes are chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles...
is often incorporated into an otherwise conventional organic reagent as an affinity tag
Affinity chromatography
Affinity chromatography is a method of separating biochemical mixtures and based on a highly specific interaction such as that between antigen and antibody, enzyme and substrate, or receptor and ligand.-Uses:Affinity chromatography can be used to:...
to facilitate recovery of a catalyst, reaction product, or reaction byproduct
By-product
A by-product is a secondary product derived from a manufacturing process or chemical reaction. It is not the primary product or service being produced.A by-product can be useful and marketable or it can be considered waste....
. The rationale for using fluorous tags in synthesis or separation is the notion of the fluorous phase, a partitioning
Partition coefficient
In chemistry and the pharmaceutical sciences, a partition- or distribution coefficient is the ratio of concentrations of a compound in the two phases of a mixture of two immiscible solvents at equilibrium. The terms "gas/liquid partition coefficient" and "air/water partition coefficient" are...
modality distinct from polar
Chemical polarity
In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...
/non-polar or hydrophilic/hydrophobic. Although many fluorochemicals are known to have toxic effects, the high affinity of fluorous tags for fluorous phases or fluorous-derivatized solid phases allows for near complete recovery of the tagged reagent (i.e., near complete reduction in a chemical waste stream), making the use of fluorous chemistry techniques a popular topic in green chemistry
Green chemistry
Green chemistry, also called sustainable chemistry, is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances...
.