[375-72-4] · C4F10O2S · Nonafluorobutanesulfonyl Fluoride · (MW 302.11)
(mild alkylating reagent for amines and alkoxysilanes; precursor for nonafluorobutanesulfinic and -sulfonic acids and various nonafluorobutyl sulfones)
Alternate Name: NfF.
Physical Data: bp 65-66 °C/760 mmHg; d 1.682 g cm-3.
Solubility: sol ether, THF; insol CH2Cl2.
Form Supplied in: colorless to pale yellow liquid of 90% purity; impurities are branched nonafluorobutanesulfonyl fluorides.
Purification: dried over CaCl2 and distilled.
Handling, Storage, and Precautions: store in amber colored bottles protected from light; for prolonged storage, PVC bottles are recommended.
The title reagent reacts with alcohols containing electronegative groups in the presence of Triethylamine to afford the nonafluorobutanesulfonate esters (nonaflates) (eqs 1 and 2).4,5 Under these conditions ethanol, for example, affords diethyl ether by alkylation of the ethanolate anion (from EtOH and Et3N) with the formed ethyl nonaflate (eq 3).
Phenols react with NfF in the presence of Et3N to form aryl nonaflates in good yields, and these were hydrogenated using Pd/C (10%) as catalyst to give arenes (eq 4).6 This has found application in the steroid field.7
Sodium phenolates also react with NfF in ether to afford aryl nonaflates (eq 5).8a For ether insoluble systems, especially heterocyclic hydroxy compounds, dimethoxyethane can be substituted as a more suitable solvent.6
A milder method of preparation of aryl nonaflates is the reaction of aryloxysilanes with NfF in the presence of fluoride ion (eq 6).9 This reaction has been extended to prepare vinyl nonaflates from the corresponding silyl ethers (eq 7).8b,c
Nonafluorobutanesulfonamides have been prepared by the reaction of NfF with an excess of NH3 (eq 8).10 The corresponding ammonium salt formed during this reaction has been isolated,11 and on acidification with HCl liberates the weakly acidic sulfonamide (eq 9). The sulfonamides have been used in preparing imides and their chemistry studied.12
NfF was hydrolyzed with aqueous Barium Hydroxide, and the barium salt formed was acidified to give nonafluorobutanesulfonic acid. This acid was converted to the nonafluorobutanesulfonic anhydride (Nf2O) by treatment with Phosphorus(V) Oxide (eq 10).13 Nf2O can be used instead of Trifluoromethanesulfonic Anhydride to prepare the homologous nonaflates, which solvolyze about twice as fast as do the triflates.13
Hydrazine is found to reduce NfF in ether to give hydrazinium nonaflinate (eq 11), which is hydrolyzed by passing gaseous HCl into the mixture (eq 12).14 The nonafluorobutanesulfinic acid obtained is useful in preparing nonafluorobutane sulfones (nonaflones) (eq 13).14
Nonaflones are also obtained by the reaction of NfF with Grignard reagents (eq 14)15 and with organolithium reagents (eq 15).16
NfF reacts with the sodium salt of Diethyl Malonate at 20 °C to afford the corresponding nonaflone, which can be hydrolyzed with 40% H2SO4 (eq 16).17
The nonaflones are useful synthetic intermediates in preparing vinyl nonaflones.16
Lakshminarayanapuram R. Subramanian, Antonio García Martínez & Michael Hanack
Universität Tübingen, Germany