Anodic oxidation trifluoromethylated

The anodic oxidation of trifluoroacetic acid affords the trifluoromethyl radical CFj. Addition of this radical to unsaturated heterocycles can produce bis(trifluoromethylated) compounds (Scheme 119) [225]. 

Other sources of radical CF3, much less expensive than CF3I, have been discovered. These are the anodic oxidation of sodium trifluoroacetate (the decomposition being initated by a hydroperoxide or ruthenium catalyst) and trifluoromethyl bromide (CF3Br) using sodium dithionite as initiating agent. ... 

Trifluoromethylated sulfenimines which are useful starting materials for the preparation of A(-fluoroalkylamines, aminoketones and aminoalkanoates, have been prepared by the anodic oxidation of 2,2,2-trifluoroethylamine and diaryl sulfides in MeCN/Et4NC104 with MgBr2 as the redox mediator (Scheme 49) [276]. 

Electrochemical Synthesis of Fluoroalkylated Sulfenimines. 83 Anodic Oxidation of Trifluoromethylated Carboxylic... 

Anodic oxidation of iV,AT-disubstituted trifluoroetbaiiimidamines 26 in dry acetonitrile gives iV-substituted 2-(trifluoromethyl)benzimi-dazoles 27 as shown in Scheme 22. °° ° Electron-donating para-substituents in the iV,lV -diaryl derivatives markedly promote this cyclization process, whereas -alkyl derivatives react to form p-ben-zoquinone imine derivatives 28 under the anodic oxidation conditions. 

Trifluoromethyl-indoles can be prepared in a similar manner as shown in Eq. 64. In this case, anodic oxidation provides p-benzo-quinone imine derivatives 29, which are easily converted into trifluoromethyl-indoles 30 by heating or by treatment with ceric ammonium nitrate. 

ANODIC OXIDATION OF TRIFLUOROMETHYLATED CARBOXYLIC ACIDS AND TRIFLUOROMETHYLSULFINIC ACID... 

In contrast to trifluoroacetate, the trifluoromethanesulfinate ion can be oxidized at a much less positive potential. Quite recently, Ignat ev and co-workers have found that anodic oxidation of sodium trifluoromethanesulfinate results in generation of the trifluoromethyl radical, which can be trapped by arenes and followed by reoxidation and deprotonation, provides trifluoromethylated arenes in ca. 50% yield as shown in Eq. 74. ... 

Kubota T, Aoyagi R, Sando H, Kawasumi M, Tanaka T (1987) Preparation of Trifluoromethylated Compounds by Anodic Oxidation of 3-Hydroxy-Trifluoromethyipropionic acid. ChemLett 1435-1438... 

Recently, Uneyama et al. have systematically investigated the anodic generation of CF3 radicals and their utilization (Scheme 7.3) [68-72], They have clarified that trifluoromethyl radicals can be generated almost quantitatively in the oxidation of TFA at 0 °C in an aq. MeOH/Pt system using an undivided cell [70]. They have also found that the trifluoromethylation of electron-deficient olefins can be controlled by the current density, reaction temperature, and the substituents of the olefins. Interestingly, anodic trifluoromethylation of fumar-... 

Further research on the substitution of the thiophene 3-position with phenyl groups containing electron-withdrawing or electron-donating groups (such as methyl, methoxy, fluoro, chloro, bromo, trifluoromethyl, sulfoxy) in the para position have lead to polymers with unique features [57]. The electron-withdraw-ing groups allow the formation of a radical anion and thus stabilize the n-doped state. As a result, such conducting polymers can be reversibly oxidized and reduced and electrochromic devices can be built with identical anode and cathode materials [58]. 

The formation of Cu-Sn alloy by galvanic contact deposition in the trimethyl-n-hexylammonium [bis(trifluoromethyl)sulfonyl]amide ([TMHAl TfiN ) ionic liquid at a temperature above 100 °C has been demonstrated by Katase et al. [41] Sn(II) was introduced into the liquid by dissolution of the SnflT N) salt which has a solubility of 0.2 mol dm f In the plating cell, a copper sheet was used as the cathodic substrate, a Sn sheet was used as the anode, and a Sn rod immersed in the same solution was used as a quasi-reference electrode. On short-circuiting, the Sn anode was oxidized to Sn(II) giving two electrons through external circuit to... 

The electrodeposition of Zn-Mn was investigated at 80 °C in the hydrophobic tri-1-butylmethylammonium bis((trifluoromethyl)sulfonyl)amide ([TBMA]+Tf2N ) [46] ionic liquid containing Zn(II) and Mn(II) species that were introduced into the ionic liquid by anodic dissolution of the respective metal electrodes. Cyclic voltam-mograms indicated that the reduction of Zn(II) occurs at a potential less negative than that of the Mn(II). Due to some kinetic limitations, which is a common phenomenon in air- and water-stable ionic liquids, incomplete oxidation of Mn electrodeposits was observed in this system. The current efficiency of Mn electrodeposition in this ionic liquid approaches 100%, which is a great improvement compared to the results obtained in aqueous solution (20-70%). Electrodeposition of Zn-Mn alloy coatings has never been carried out in chloroaluminate ionic liquid because of the unavoidable codeposition of Mn and Al. 

The characteristics of the electrooxidation of fluorosulfate anions in the electrolysis of a potassium fluorosulfate solution in fluorosulfonic acid have been investigated. The formation of oxide layers on platinum and the modification of glassy carbon with fluorosulfate groups during anodic polarization in fluorosulfonic acid are studied. The reactions of fiuoroolefin fluorosulfation are considered and a mechanism is suggested223. Trifluoromethylation of carbonyl compounds can be achieved using bromo-trifluoromethane and a sacrificial electrode in solvents such as DMF/pyridine, and DMF/TMEDA, as seen in equation 126224. 

Recently, anodic generation of the CF3 radical and its trapping reactions have been systematically studied by Uneyama and his coworkers (Scheme 24). "" This work has demonstrated that tri-fluoromethyl radicals can be generated almost quantitatively by the oxidation of TFA at 0 °C in an aqueous MeOH/Pt system using a divided cell." Also, it has been found that additions of the tri-fluoromethyl radical to electron-deficient olefin can be controlled by the choice of current density, reaction temperature, and olefin substituents. Notably, anodic trifluoromethylation of fumaronitrile leading to 31 (Scheme 25) is greatly affected by the reaction temperature. The... 

---