Selectfluor

Selectfluor
Names
	IUPAC name 1-(Chloromethyl)-4-fluoro-1,4-diazabicyclo[2.2.2]octane-1,4-diium ditetrafluoroborate
	Other names F-TEDA, N-Chloromethyl-N-fluorotriethylenediammonium bis(tetrafluoroborate); 1-Chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)
Identifiers
CAS Number	140681-55-6 ;
3D model (JSmol)	Interactive image;
ChemSpider	2007047 ;
ECHA InfoCard	100.101.349
EC Number	414-380-4;
PubChem CID	2724933;
UNII	4P1ZA6R76D ;
CompTox Dashboard (EPA)	DTXSID0073112 ;
	InChI InChI=1S/C7H14ClFN2.2BF4/c8-7-10-1-4-11(9,5-2-10)6-3-10;22-1(3,4)5/h1-7H2;;/q+2;2-1 Key: TXRPHPUGYLSHCX-UHFFFAOYSA-N ; InChI=1/C7H14ClFN2.2BF4/c8-7-10-1-4-11(9,5-2-10)6-3-10;22-1(3,4)5/h1-7H2;;/q+2;2-1 Key: TXRPHPUGYLSHCX-UHFFFAOYAI;
	SMILES [B-](F)(F)(F)F.[B-](F)(F)(F)F.C1C[N+]2(CC[N+]1(CC2)CCl)F;
Properties
Chemical formula	C7H14B2ClF9N2
Molar mass	354.26 g/mol
Appearance	colourless solid
Melting point	190 °C (374 °F; 463 K) decomposes >80 °C, exact m.p. is uncertain
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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. It is a colourless salt that tolerates air and even water. It has been commercialized for use for electrophilic fluorination.^[1]

Preparation

Selectfluor is synthesized by the N-alkylation of diazabicyclo[2.2.2]octane (DABCO) with dichloromethane in a Menshutkin reaction, followed by ion exchange with sodium tetrafluoroborate (replacing the chloride counterion for the tetrafluoroborate). The resulting salt is treated with elemental fluorine and sodium tetrafluoroborate:^[2]

The cation is often depicted with one skewed ethylene ((CH₂)₂) group. In fact, these pairs of CH₂ groups are eclipsed so that the cation has idealized C_3h symmetry.

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.^[2] By using a charge-spin separated probe,^[3] it was possible to show that the electrophilic fluorination of stilbenes with Selectfluor proceeds through an SET/fluorine atom transfer mechanism.^[4]

In certain cases Selectfluor can transfer fluorine to alkyl radicals.^[5]

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:^[2]

Specialized applications

Selectfluor reagent also serves as a strong oxidant, a property that is useful in other reactions in organic chemistry. Oxidation of alcohols and phenols. As applied to electrophilic iodination, Selectfluor reagent activates the I–I bond in I₂ molecule.^[6]

Related reagents

Similar to Selectfluor are N-fluorosulfonimides:^[7]

References

^ ^a ^b Banks, R. Eric; Murtagh, Vincent; An, Ilhwan; Maleczka, Robert E. (2007). "1-(Chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane Bis(tetrafluoroborate)". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rc116.pub2. ISBN 978-0471936237.
^ ^a ^b ^c Nyffeler, Paul T.; Durón, Sergio Gonzalez; Burkart, Michael D.; Vincent, Stéphane P.; Wong, Chi-Huey (2005). "Selectfluor: Mechanistic Insight and Applications". Angewandte Chemie International Edition. 44 (2): 192–212. doi:10.1002/anie.200400648. PMID 15578736.
^ Tojo, Sachiko; Morishima, Kazuhiro; Ishida, Akito; Majima, Tetsuro; Takamuku, Setsuo (1995). "Remarkable Enhancements of Isomerization and Oxidation of Radical Cations of Stilbene Derivatives Induced by Charge-Spin Separation". The Journal of Organic Chemistry. 60 (15): 4684–4685. doi:10.1021/jo00120a004. ISSN 0022-3263.
^ Brandt, Jochen R.; Lee, Eunsung; Boursalian, Gregory B.; Ritter, Tobias (2014). "Mechanism of electrophilic fluorination with Pd(iv): fluoride capture and subsequent oxidative fluoride transfer". Chem. Sci. 5 (1): 169–179. doi:10.1039/C3SC52367E. ISSN 2041-6520. PMC 3870902. PMID 24376910.
^ Paquin, J.-F.; Sammis, G.; Chatalova-Sazepin, C.; Hemelaere, R. (2015). "Recent advances in radical fluorination". Synthesis. 47 (17): 2554–2569. doi:10.1055/s-0034-1378824. S2CID 196807570.
^ Stavber, Stojan; Kralj, Petra; Zupan, Marko (2002-08-01). "Progressive Direct Iodination of Sterically Hindered Alkyl Substituted Benzenes". Synthesis. 2002 (11): 1513–1518. doi:10.1055/s-2002-33339. ISSN 0039-7881.
^ Baudoux, Jérôme; Cahard, Dominique (2008). "Electrophilic Fluorination with N–F Reagents". Organic Reactions. pp. 1–326. doi:10.1002/0471264180.or069.02. ISBN 978-0-471-26418-7.

Patents

US 5459267 "1-substituted-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane salts and their application as fluorinating agents"
US 55227493 "Fluorinated Sulfonamide Derivatives"
US 5086178 "Fluorinated Diazabicycloalkane Derivatives"
US 5473065 "Fluorinated Diazabicycloalkane Derivatives"
US 5442084 "Method of Selective Fluorination"

[eEROS-1] Banks, R. Eric; Murtagh, Vincent; An, Ilhwan; Maleczka, Robert E. (2007). "1-(Chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane Bis(tetrafluoroborate)". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rc116.pub2. ISBN 978-0471936237.

[Angew-2] Nyffeler, Paul T.; Durón, Sergio Gonzalez; Burkart, Michael D.; Vincent, Stéphane P.; Wong, Chi-Huey (2005). "Selectfluor: Mechanistic Insight and Applications". Angewandte Chemie International Edition. 44 (2): 192–212. doi:10.1002/anie.200400648. PMID 15578736.

[TojoMorishima1995-3] Tojo, Sachiko; Morishima, Kazuhiro; Ishida, Akito; Majima, Tetsuro; Takamuku, Setsuo (1995). "Remarkable Enhancements of Isomerization and Oxidation of Radical Cations of Stilbene Derivatives Induced by Charge-Spin Separation". The Journal of Organic Chemistry. 60 (15): 4684–4685. doi:10.1021/jo00120a004. ISSN 0022-3263.

[BrandtLee2014-4] Brandt, Jochen R.; Lee, Eunsung; Boursalian, Gregory B.; Ritter, Tobias (2014). "Mechanism of electrophilic fluorination with Pd(iv): fluoride capture and subsequent oxidative fluoride transfer". Chem. Sci. 5 (1): 169–179. doi:10.1039/C3SC52367E. ISSN 2041-6520. PMC 3870902. PMID 24376910.

[5] Paquin, J.-F.; Sammis, G.; Chatalova-Sazepin, C.; Hemelaere, R. (2015). "Recent advances in radical fluorination". Synthesis. 47 (17): 2554–2569. doi:10.1055/s-0034-1378824. S2CID 196807570.

[6] Stavber, Stojan; Kralj, Petra; Zupan, Marko (2002-08-01). "Progressive Direct Iodination of Sterically Hindered Alkyl Substituted Benzenes". Synthesis. 2002 (11): 1513–1518. doi:10.1055/s-2002-33339. ISSN 0039-7881.

[OR-7] Baudoux, Jérôme; Cahard, Dominique (2008). "Electrophilic Fluorination with N–F Reagents". Organic Reactions. pp. 1–326. doi:10.1002/0471264180.or069.02. ISBN 978-0-471-26418-7.

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