Selectfluor, a trademark of Air Products and Chemicals, 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 reage ...

. It is a colourless salt that tolerates air and even water. It has been commercialized for use for electrophilic fluorination.

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 effectin ...

of diazabicyclo .2.2ctane (DABCO) with

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible wit ...

, 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 (replacing the chloride

counterion 160px, cation-exchange_resin.html" ;"title="Polystyrene sulfonate, a cation-exchange resin">Polystyrene sulfonate, a cation-exchange resin, is typically supplied with as the counterion. In chemistry, a counterion (sometimes written as "counter ...

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 S_N2 attack at fluorine. This distinction has not been decided. By using a charge-spin separated probe, it was possible to show that the electrophilic fluorination of stilbenes with Selectfluor proceeds through an SET/fluorine atom transfer mechanism. In certain cases Selectfluor can transfer fluorine to alkyl radicals.

Applications

The conventional source of "electrophilic fluorine", i.e. the equivalent to the

superelectrophile In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carries ...

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 compound Organofluorine chemistry describes the chemistry of the organofluorines, organic compounds that contain the carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, r ...

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 science, 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.Clay ...

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 ...

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

s 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 ...

. As applied to

electrophilic iodination In organic chemistry, an electrophilic aromatic halogenation is a type of electrophilic aromatic substitution. This organic reaction is typical of aromatic compounds and a very useful method for adding substituents to an aromatic system. : A few ...

, Selectfluor reagent activates the I–I bond in I₂ molecule.

References

Patents

* * * * * {{Tetrafluoroborates Reagents for organic chemistry Tetrafluoroborates Fluorinating agents Quaternary ammonium compounds Nitrogen heterocycles Organochlorides Substances discovered in the 1990s