Electrocarboxylation. II. Electrocarboxylative dimerization and cyclization

Abstract

buret. The rate of addition was such that a maximum current of 0.6 A was passed. The electrolysis was discontinued when the current had fallen to 0.05 A. For cie experiments 0.07 mol of the olefin was taken up in acetonitrile (total volume of 25 ml) and the solution was added to the catholyte at a rate equivalent to 5.6 X 10~3 mol/hr with a syringe pump. A constant current of 0.3 A was maintained [i.e., 0.3 A = (53.6 A hr/mol)(5.6 X 10~3 mol/hr)]. The catholyte was continuously saturated with C02 during the electrolyses. The cathode potential was monitored with a see.General Electrolysis Procedure. Monocarboxylation. The apparatus employed is shown in Figure 3. The top layer of propionitrile [0.06 M in (CiHg^N+BFu and 2.8 M in H20] was circulated through the cell while being saturated with 100% CO2 for 15 min prior to starting the electrolysis. Acrylonitrile was then added at a rate of 2.43 g/hr to the circulating propionitrile electrolyte solution (continuous C02 saturation). A constant current of 2.35 A was maintained [i.e., 2.35 A = (53.6 A hr/mol)(4.38 X 1CH2 mol/ hr)].Work-Up and Analyses of Catholytes. The products of electrocarboxylation under anhydrous conditions were converted to their methyl esters by treating the catholyte solution directly with an excess (0.28 mol) of methyl iodide at ice-bath temperatures (c/.footnote c of Table II). The acetonitrile and excess methyl iodide were removed and the organic products were separated from the electrolyte by benzene-water extraction. If authentic samples were available, analyses were done directly on the benzene-soluble material by glc (internal standards), using one of the following columns and conditions: (a) 6 ft X 0.125 in. S.S. 3% OV-101 on Chromosorb W (80-100 mesh), 150 -» 280°at 10°/min; (b) 10 ft X 0.125 in. S.S. 5% FFAP + 1% Carbowax 20M on Chromosorb G (80-100 mesh), 100 -200°at 10°/min; (c) 10 ft X 0.125 in. S.S. 3% QF-1 on Gas Chrom Q (60-80 mesh), 100 -* 200°at 10°/min. Products for which authentic samples were not available were isolated by distillation and/or preparative glc. The following column and conditions were used: 3 ft X 0.75 in. S.S. 30% FFAP + 6% Carbowax 20M on Chromosorb W (60-80 mesh), 200°. The products so obtained were subsequently used for yield determinations by glc (internal standards). Yield data for electrocarboxylations under partially aqueous conditions were obtained by analyzing the aqueous extract by nmr using sodium acetate as an internal standard.Identification of Products. Products were confirmed by comparing their glc retention lines, mass spectra, nmr spectra, and boiling points. New compounds were identified by their mass spectra, nmr spectra, and elemental analyses. These compounds and the appropriate analytical data are given in Table III.

Long-Lived Short-Distance Intramolecular Charge Separation via Intermolecular Triplet Sensitisation

“…Lower limits for the singlet energies of DCME [3], diethylfumarate and diethylmaleate were estimated from the onset of their S 0 -S 1 absorption. [a] E red [V] [a] DMN [4] 3.78 [21] 2.65 [22,23] 1.1 [21] DCME [3] b 4.5 ± À 1.60 [21] Benzophenone [24] 3.26 2.96 À 1.83 Diethylfumarate b 4.5 2.65 [25] À 1.45 [26] Diethylmaleate b 4.5 3.2 AE 0.1 [25] À 1.70 [27] [a] Versus standard calomel electrode in acetonitrile. triplet nature of the charge-transfer state formed via sensitised excitation as well as the fact that it is (in polar solvents) the lowest triplet state available to the DMN[3]DCME system.…”

Electrochemical fixation of CO2 to organohalides in room-temperature ionic liquids under supercritical CO2

“…In the electrochemical methods, highly reactive carbon nucleophiles are readily generated at cathodes and then react with CO 2 immediately to provide the corresponding carboxylated products. Over the past several decades, there have been many reports on the electrochemical fixation of CO 2 to various types of organic compounds such as organohalides [6][7][8][9][10][11][12][13][14][15][16], activated olefins [17][18][19], imines [20][21][22][23][24], and ketones [25][26][27][28] in conventional polar organic solvents. In addition, some of them focused on the effect of the pressure of CO 2 on electrocarboxylation processes [27,28].…”

Electrochemical Fixation of Carbon Dioxide

“…Consequently, selective synthesis of each carboxylic acid 15, 16, 17, and 18 from terminal alkyne 14 and carbon dioxide can be accomplished even by selecting appropriate ligands on nickel(II) complexes in the electrochemical carboxylation (Scheme 10.7). As a similar manner, control Carboxylation can take place with other electrochemically induced chemical reactions such as cyclization [75][76][77]. For example, electrochemical carboxylation of 2-allyloxybromobenzene (23) [51,71] followed by enantioselective hydrogenation.…”