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)<br/>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<ref name=eEROS/> | 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.<ref name=eEROS>{{cite book |doi=10.1002/047084289X.rc116.pub2|chapter=1-(Chloromethyl)-4-fluoro-1,4-diazoniabicyclo&#91;2.2.2&#93;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}}</ref>

==Preparation== :550px|F-TEDA-BF4 synthesis Selectfluor is synthesized by the ''N''-alkylation of [[DABCO|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:<ref name=Angew/>

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.<ref name=Angew>{{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}}</ref> By using a charge-spin separated probe,<ref name="TojoMorishima1995">{{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}}</ref> it was possible to show that the electrophilic fluorination of stilbenes with Selectfluor proceeds through an SET/fluorine atom transfer mechanism.<ref name="BrandtLee2014">{{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}}</ref>

In certain cases Selectfluor can transfer fluorine to alkyl radicals.<ref>{{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 }}</ref>

==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:<ref name=Angew/> 350px|center

===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.<ref>{{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}}</ref>

==Related reagents== Similar to Selectfluor are ''N''-fluorosulfonimides:<ref name=OR>{{cite book|doi=10.1002/0471264180.or069.02 |chapter=Electrophilic Fluorination with N–F Reagents |title=Organic Reactions |date=2008 |last1=Baudoux |first1=Jérôme |last2=Cahard |first2=Dominique |pages=1–326 |isbn=978-0-471-26418-7 }}</ref> center|444px

==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:Tetrafluoroborates Category:Fluorinating agents Category:Quaternary ammonium compounds Category:Nitrogen heterocycles Category:Chloromethyl compounds Category:Substances discovered in the 1990s