The structure of the tert-butyl cation (1) could be determined by an X-ray crystal structure analysis of its Sb2F11- salt at -80-degrees-C (P2(1), a = 6.123(2) angstrom, b = 13.758(4) angstrom, c = 7.614(4) angstrom, beta = 100.67(3)degrees; R = 0.029, R(w) = 0.029). Suitable crystals of 1.Sb2F11 were obtained only from a methylene chloride solution of the corresponding tert-pentyl salt by slow decomposition. The cation is planar within our limits of accuracy, the C+-C bonds have an average length of 1.442(5) angstrom, and the C-C+-C bond angles are 120(1)degrees. These results agree with the nutation NMR results of Yannoni, Myhre, et al. and recent ab initio results of Schleyer et al. In the crystal, the cation is surrounded by fluorine atoms from a total of eight counterions. The packing motif of cations and anions is similar to that of CsCl. Several other simple tertiary alkyl salts gave no suitable crystals for an X-ray structure determination.
Determination and interpretation of second order rate constants for the addition of hydrogen halides to alkenes
作者:Robert Borgeaud、Henry Newman、Arabella Schelpe、Veronica Vasco、D. E. Peter Hughes
DOI:10.1039/b108199n
日期:2002.3.25
An extensive range of second order rate constants for the addition of hydrogen halides to alkenes in 98% v/v ethanoic acid (acetic acid)–water have been obtained by conductivity measurements. The rate constants are in the expected order of HF < HCl < HBr < HI. The rates with different alkenes cannot be rationalised solely by a consideration of carbocation stability and it has been necessary to consider
Mechanistic Study of Silver-Catalyzed Decarboxylative Fluorination
作者:Niki R. Patel、Robert A. Flowers
DOI:10.1021/acs.joc.5b00826
日期:2015.6.5
components and ligates to Ag(I) under the reaction conditions. The use of donor ligands on Ag(I) provides evidence of oxidation to Ag(II) by Selectfluor. The use of sodium persulfate as an additive in the reaction as well as NFSI as a fluorine source further supports the generation of a Ag(II) intermediate; this data will enable the development of a more efficient set of reaction conditions for the fluorination
Cu2-O-HF-Organic base (tetrahydrofuran or Et2-O) solutions were used successively as a highly reactive halogen-exchange fluorination reagent for the cyclo or tertiary alkyl halides without carbon skeletal rearrangement under the mild conditions.