Synthesis and characterization of 1,2-bis (chlorosulfonyl) tetrafluoroethane and 1,2-bis (fluorosulfonyl) tetrafluoroethane

A New Motif in Halogen Bonding: Cooperative Intermolecular S−Br⋅⋅⋅O, O⋅⋅⋅F, and F⋅⋅⋅F Associations in the Crystal Packing of α,ω‐Di(sulfonyl bromide) Perfluoroalkanes

“…Nevertheless, when starting with α,ω-dibromoperfluoroalkanes, we were able to obtain as crystalline solids the C4, C6, and C8 α,ω-di(sulfonyl bromide) perfluoroalkanes, where the carbon number (C#) refers to the number of CF 2 groups in the perfluoroalkane chain or twice the value of "n" in Scheme 1, i. e., twice the number of À CF 2 CF 2 À linkages. Although Umemoto and Saito only gave synthetic details and partial characterization (melting points and 19 F-and 13 C-NMR spectra) of BrSO 2 (CF 2 ) 3 SO 2 Br and BrSO 2 (CF 2 ) 4 SO 2 Br in their patent, they claimed α,ω-di(sulfonyl bromide) perfluoroalkanes from C3 to C10. [11] They also described their materials (C3 and C4) as needle-shaped crystals when recrystallized from a mixture of dichloromethane (DCM) and n-pentane, [11] while in our hands, we obtained plate-like crystals when the products were recrystallized by slow cooling of saturated solutions of either DCM or n-hexane (see Table S1).…”

“…As alluded to above and shown in Scheme 1, we used a modified version of the synthetic method of Umemoto and Saito to prepare α,ω-di(sulfonyl bromide) perfluoroalkanes starting with α,ω-dibromoperfluoroalkanes and going through the intermediacy of disodium salts of the corresponding α,ωdi(sulfinate) perfluoroalkanes, which were then further reacted with elemental bromine to give the desired products. [11] Since we already had a number of α,ω-diiodoperfluoroalkanes in laboratory stock, we first tried to no avail their well-known deiodosulfination reaction [16][17][18][19] followed by the addition of bromine; evidently, the redox activity of some of the coproducts remaining in solution does not allow for the formation of the desired disulfonyl bromides in this manner. Nevertheless, when starting with α,ω-dibromoperfluoroalkanes, we were able to obtain as crystalline solids the C4, C6, and C8 α,ω-di(sulfonyl bromide) perfluoroalkanes, where the carbon number (C#) refers to the number of CF 2 groups in the perfluoroalkane chain or twice the value of "n" in Scheme 1, i. e., twice the number of À CF 2 CF 2 À linkages.…”

“…In addition to 19 F-and 13 C-NMR spectroscopy [see Supporting Information (SI) Figures S2, S3, S6, S7, S10, and S11], we characterized the C4, C6, and C8 α,ω-di(sulfonyl bromide) perfluoroalkanes not only by single-crystal X-ray diffraction, but also by attenuated total reflectance (ATR) Fourier transforminfrared (FT-IR) spectroscopy (see Figures S4, S8, and S12) and electrospray ionization (ESI) liquid chromatography-mass spectrometry (LC-MS) (see Figures S5, S9, and S13). Both the 19 F-and 13 C-NMR spectroscopic data of C4 (BrSO 2 (CF 2 ) 4 SO 2 Br, Figures S2 and S3) agree with that of Umemoto and Saito; [11] however, searches in Scifinder® indicate that the C6 and C8 derivatives are new compounds (Figures S6, S7, S10, and S11). With respect to the infrared spectra, each α,ω-di(sulfonyl bromide) perfluoroalkane displays the characteristic asymmetric and symmetric À SO 2 À stretching frequencies in the vicinity of 1395 cm À 1 and 1170 cm À 1 , respectively, along with the usual CÀ F stretching frequencies associated with À CF 2 À groups in the region of 1250 to 1070 cm À 1 .…”