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Short-lived (f 1/2 < 10-3 sec) anion radicals of activated olefins (CH2=CHX with X = CO2CH3, CN, and acetyl) generated at a mercury cathode under anhydrous conditions react rapidly with carbon dioxide. Further reduction of the radical carboxylate intermediate and subsequent carboxylation results in the formation of substituted succinic acid derivatives. An alternate pathway involves electroreduction of carbon dioxide and subsequent reactions

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.

It is shown that in mixed reductive coupling of activated olefins A and B, in which A is reduced at the more anodic voltage, the ratio of cross‐coupled product HABH to self‐coupled product HAAH rises substantially as the controlled potential is made more negative. Diethyl maleate (DEM) was chosen as an example of A and ethyl acrylate (EA) and acrylonitrile (AN) as examples of B. Previously reported fluctuations of voltage along the cathode surface are confirmed and may lead to unexpected formation of HBBH. The results of cyclic voltammetry of DEM in the presence of EA or AN and of a kinetic study of the addition of a carbanion to these same acceptors in bulk are interpreted to indicate that the reductive coupling of DEM with the acceptors occurs largely but not exclusively at the electrode surface.

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