Electronegatively substituted carbocations

A Novel, One‐Pot Synthesis of Novel 3F, 5F, and 8F Aromatic Polymers

“…[6] Apart from that, the reactivity (electrophilicity) of the carboxonium ion can also be increased by the presence of electron-withdrawing substituent, adjacent or relatively close to a carbocation center. [7] Taking into account the strong electron-withdrawing effect of the fluorine atom, one can expect that fluorinated aldehydes and ketones would react with non-activated aromatic hydrocarbons under superacid conditions to yield high-molecular-weight polymers.…”

Selective synthesis of fluorinated benzyl- or phenylpyrimidines from the heterocyclisation of α-trifluoroacetylarylpropanenitriles

“…Thus two types of mechanism can be considered (Scheme 3): formation of stable allyl/benzyl carbocations (the positive charge is also delocalized around the benzene ring) or a concerted allylic S N 2 0 process. In the first case, a S N 1 mechanism is possible because such cations (with a CF 3 group placed on the a-position) can be generated, studied, and used in synthetic applications [11].…”

Correlation of the rates of solvolysis of α-bromoisobutyrophenone using both simple and extended forms of the Grunwald-Winstein equation and the application of correlation analysis to related studies

“…The purifications of acetone [12], ethanol [16], methanol [16], 2,2,2-trifluoroethanol (TFE) [17], and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)[18] were as previously described. All kinetic runs were performed with 5×10 -3 M substrate in the appropriate solvent contained within sealed tubes at 62.5 °C, usually with 5 mL aliquots, but with 2 mL aliquots for the runs in HFIP-H 2 O mixtures.…”

“…It is of interest to investigate the corresponding solvolysis of the tertiary alpha-bromoketone α-bromoisobutyrophenone (2-benzoyl-2-bromopropane, C6H5COC(CH3)2Br, 2 ) to see whether it follows the same pathway as 1 or whether there is a partial or complete movement towards a unimolecular pathway involving formation of a carbocation, as has been proposed for the solvolyses of several tertiary ketones related to 2 but with a considerably more effective leaving group (nucleofuge) such as methanesulfonate (mesylate) or trifluoromethanesulfonate (triflate) [10-12]. An alternative approach for generating carbocations, with the charge primarily at the α-carbon, is to use tertiary α-haloketones in the presence of silver-ion [13], with the complexation of the chlorine, bromine or iodine with the silver-ion providing an alternative route to an effective leaving group [14].…”