Electrocatalytic carboxylation of aliphatic halides at silver cathode in acetonitrile

Electrocarboxylation of Dichlorobenzenes on a Silver Electrode in DMF

“…Nucleophilicity decreased in the following order: 8a > 8b > 8c. When the electrocarboxylation was carried out using 1b or 1c as a substrate, the weak nucleophilicity of the carbon anion of 8b or 8c might have prevented 8b or 8c from attacking CO 2 in a nucleophilic manner even when a small amount of 8b or 8c was generated [18]. Furthermore, based on the energy calculations, the energy differences of 4b-8b and 4c-8c were surprisingly higher than that of 4a-8a (Scheme 2).…”

“…Notably, with the same tetraalkylammonium cation, the total carboxylation yield dependences on the anion were in the following order: Cl −1 > Br −1 > I −1 ( Table 1, entries 1-3, 5-7). Although negatively charged in the Ag electrode, inorganic halide anions have been reported to remain powerfully absorbed in the Ag electrode in the sequence of Cl −1 ≤ Br −1 ≤ I −1 and are thus accorded with many well-known halide properties, such as the solubility of products with Ag ions [18,55]. In addition, with the same anion of Cl −1 , Br −1 , and I −1 , the synthesis carried out with the TBA + cation provided better yields than those of the TEA + cation cases (Table 1, entries 1-3, 5-7), indicating that the cations exerted some influence on the electrolysis.…”

“…Therefore, electrocarboxylation is a facile method of CO 2 fixation from ecological and economic viewpoints. Many substrate types, alcohols [14], epoxides [15,16], imines [17], organic halides [13,[18][19][20][21][22][23][24][25][26][27][28], ketones [11,12,[29][30][31][32], aldehydes [33], alkenes [34][35][36][37][38], and alkynes [39] have been used in previous studies.…”

“…However, Hg is discarded for environmental reasons. Meanwhile, studies have indicated that silver (Ag) exhibits extraordinary electrocatalytic activities toward the reduction of organic halides [13,[18][19][20][21][22][23]43,44]. Although many studies have investigated electroreduction and electrocarboxylation of organic chlorides, most of them focused on monochloride compounds [19,21,22,[40][41][42][43][44].…”

“…As shown in curves b and e, the two reduction peaks shifted to a more positive potential because of the electrocatalytic properties of the Ag electrode. The electrocatalytic activities of electrode materials for the reduction of organic halides have been the subject of many studies [18,19,21,22,[52][53][54]. These studies have shown that Ag exhibits powerful electrocatalytic activities toward the reduction of various organic halides.…”