Selectfluor
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 443880836
| ImageFileL1=F-TEDA-BF4.svg
| ImageSizeL1=100px
| ImageFileR1=Selectfluor-from-xtal-3D-balls.png
| ImageSizeR1=100px
| IUPACName=1-(Chloromethyl)-4-fluoro-1,4-diazabicyclo[2.2.2]octane-1,4-diium ditetrafluoroborate
| OtherNames=F-TEDA, N-Chloromethyl-N-fluorotriethylenediammonium bis(tetrafluoroborate)
1-Chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo=140681-55-6
| EINECS = 414-380-4
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 2007047
| PubChem= 2724933
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 4P1ZA6R76D
| InChI = 1/C7H14ClFN2.2BF4/c8-7-10-1-4-11(9,5-2-10)6-3-10;2*2-1(3,4)5/h1-7H2;;/q+2;2*-1
| InChIKey = TXRPHPUGYLSHCX-UHFFFAOYAI
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/C7H14ClFN2.2BF4/c8-7-10-1-4-11(9,5-2-10)6-3-10;2*2-1(3,4)5/h1-7H2;;/q+2;2*-1
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = TXRPHPUGYLSHCX-UHFFFAOYSA-N
| SMILES = [B-](F)(F)(F)F.[B-](F)(F)(F)F.C1C[N+]2(CC[N+]1(CC2)CCl)F
}}
|Section2={{Chembox Properties
| Formula=C7H14B2ClF9N2
| MolarMass=354.26 g/mol
| Appearance=colourless solid
| Density=
| MeltingPtC=190
| MeltingPt_notes= decomposes >80 °C, exact m.p. is uncertain
| BoilingPt=
| Solubility=
}}
|Section3={{Chembox Hazards
| MainHazards=
| FlashPt=
| AutoignitionPt =
}}
}}
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.{{cite book |doi=10.1002/047084289X.rc116.pub2|chapter=1-(Chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane Bis(tetrafluoroborate)|title=Encyclopedia of Reagents for Organic Synthesis|year=2007|last1=Banks|first1=R. Eric|last2=Murtagh|first2=Vincent|last3=An|first3=Ilhwan|last4=Maleczka|first4=Robert E.|isbn=978-0471936237}}
Preparation
:Image:F-TEDA-BF4 synthesis.svg
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:
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 C3h symmetry.
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.{{cite journal|doi=10.1002/anie.200400648|title=Selectfluor: Mechanistic Insight and Applications|year=2005|last1=Nyffeler|first1=Paul T.|last2=Durón|first2=Sergio Gonzalez|last3=Burkart|first3=Michael D.|last4=Vincent|first4=Stéphane P.|last5=Wong|first5=Chi-Huey|journal=Angewandte Chemie International Edition|volume=44|issue=2|pages=192–212|pmid=15578736|doi-access=free}} By using a charge-spin separated probe,{{cite journal|last1=Tojo|first1=Sachiko|last2=Morishima|first2=Kazuhiro|last3=Ishida|first3=Akito|last4=Majima|first4=Tetsuro|last5=Takamuku|first5=Setsuo|title=Remarkable Enhancements of Isomerization and Oxidation of Radical Cations of Stilbene Derivatives Induced by Charge-Spin Separation|journal=The Journal of Organic Chemistry|volume=60|issue=15|year=1995|pages=4684–4685|issn=0022-3263|doi=10.1021/jo00120a004}} it was possible to show that the electrophilic fluorination of stilbenes with Selectfluor proceeds through an SET/fluorine atom transfer mechanism.{{cite journal|last1=Brandt|first1=Jochen R.|last2=Lee|first2=Eunsung|last3=Boursalian|first3=Gregory B.|last4=Ritter|first4=Tobias|title=Mechanism of electrophilic fluorination with Pd(iv): fluoride capture and subsequent oxidative fluoride transfer|journal= Chem. Sci.|volume=5|issue=1|year=2014|pages=169–179|issn=2041-6520|doi=10.1039/C3SC52367E|pmc=3870902|pmid=24376910}}
In certain cases Selectfluor can transfer fluorine to alkyl radicals.{{Cite journal|title = Recent advances in radical fluorination|journal = Synthesis|year = 2015|pages = 2554–2569|volume = 47|issue = 17|doi = 10.1055/s-0034-1378824|first1 = J.-F.|last1 = Paquin|first2 = G.|last2 = Sammis|first3 = C.|last3 = Chatalova-Sazepin|first4 = R.|last4 = Hemelaere| s2cid=196807570 }}
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. Oxidation of alcohols and phenols. As applied to electrophilic iodination, Selectfluor reagent activates the I–I bond in I2 molecule.{{Cite journal|last1=Stavber|first1=Stojan|last2=Kralj|first2=Petra|last3=Zupan|first3=Marko|date=2002-08-01|title=Progressive Direct Iodination of Sterically Hindered Alkyl Substituted Benzenes|journal=Synthesis|language=en|volume=2002|issue=11|pages=1513–1518|doi=10.1055/s-2002-33339|issn=0039-7881}}
Related reagents
References
{{Reflist}}
Patents
- {{patent|US|5459267|"1-substituted-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane salts and their application as fluorinating agents"}}
- {{patent|US|55227493|"Fluorinated Sulfonamide Derivatives"}}
- {{patent|US|5086178|"Fluorinated Diazabicycloalkane Derivatives"}}
- {{patent|US|5473065|"Fluorinated Diazabicycloalkane Derivatives"}}
- {{patent|US|5442084|"Method of Selective Fluorination"}}
{{Tetrafluoroborates}}
Category:Reagents for organic chemistry
Category:Quaternary ammonium compounds
Category:Nitrogen heterocycles