Selectfluor, a trademark of
Air Products and Chemicals
Air Products and Chemicals, Inc. is an American international corporation whose principal business is selling gases and chemicals for industrial uses. Air Products' headquarters is in Allentown, Pennsylvania, in the Lehigh Valley region of Pen ...
, is a
reagent in
chemistry that is used as a
fluorine donor. This compound is a derivative of the nucleophillic base
DABCO
DABCO (1,4-diazabicyclo .2.2ctane), also known as triethylenediamine or TEDA, is a bicyclic organic compound with the formula N2(C2H4)3. This colorless solid is a highly nucleophilic tertiary amine base, which is used as a catalyst and reagen ...
. It is a colourless salt that tolerates air and even water. It has been commercialized for use for
electrophilic fluorination Electrophilic fluorination is the combination of a carbon-centered nucleophile with an electrophilic source of fluorine to afford organofluorine compounds. Although elemental fluorine and reagents incorporating an oxygen-fluorine bond can be used fo ...
.
Preparation
Selectfluor is synthesized by the ''N''-
alkylation
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecti ...
of
diazabicyclo .2.2ctane (DABCO) with
dichloromethane, followed by
ion exchange
Ion exchange is a reversible interchange of one kind of ion present in an insoluble solid with another of like charge present in a solution surrounding the solid with the reaction being used especially for softening or making water demineralised, ...
with
sodium tetrafluoroborate
Sodium tetrafluoroborate is an inorganic compound with formula NaBF4. It is a salt that forms colorless or white water-soluble rhombic crystals and is soluble in water (108 g/100 mL) but less soluble in organic solvents.
Sodium tetrafluoroborate ...
(replacing the chloride
counterion for the tetrafluoroborate). The resulting salt is treated with elemental fluorine and sodium tetrafluoroborate:
[
:
]
Mechanism of fluorination
Electrophilic fluorinating reagents could in principle operate by electron transfer pathways or an SN2 attack at fluorine. This distinction has not been decided.
Applications
The conventional source of "electrophilic fluorine", i.e. the equivalent to the superelectrophile F+, is gaseous fluorine, which requires specialised equipment for manipulation. Selectfluor reagent is a salt, the use of which requires only routine procedures. Like F2, the salt delivers the equivalent of F+. It is mainly used in the synthesis of organofluorine compounds:[
]
Specialized applications
Selectfluor reagent also serves as a strong oxidant, a property that is useful in other reactions in organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, ...
. Oxidation
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...
of alcohols and phenols
In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (— O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds are ...
. As applied to electrophilic iodination, Selectfluor reagent activates the I–I bond in I2 molecule.
References
Patents
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{{Tetrafluoroborates
Reagents for organic chemistry
Tetrafluoroborates
Fluorinating agents
Quaternary ammonium compounds
Nitrogen heterocycles
Organochlorides
Substances discovered in the 1990s