Ethanetetracarboxylate

After electrolysis the reaction mixture is allowed to cool to room temperature and is filtered (Note 6). The crystalline residue is washed three times with 100-mL portions of methanol, dried by suction on the filter, and finally dried under vacuum. The product (88.4-91 g, 67-69%) is obtained as a white solid, mp 134-135°C. 

10/18 and one 34/45 standard-taper joints. The electrodes should extend as far as possible into the electrolyte without interfering with the operation of the magnetic stirrer. 

Dimethyl 1,3-propanedioate (dimethyl malonate) was obtained from Aldrich Chemical Company, Inc., and used as supplied. 

A Heath/Schlumberger dc power supply, Model SP-2711, 30 V, 3 A, operating in its constant current mode, was used. 

The current passed is 1.01 Faraday (1 Faraday = 26.8 A-hr) and this is sufficient to convert 75-80% of the starting material to product. At higher conversions further oxidation occurs, leading to formation of tetramethyl ethenetetracarboxylate and hexa-methyl 1,1,2,2,3,3-propanehexacarboxylate. The latter has solubility properties similar to those of the desired product. The product may be contaminated with the propanehexacarboxylate ester if the reaction is taken to higher conversions. 

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The acetylenedicarboxylate 17 is a reactive compound and is carbonylated smoothly at room temperature to give the ethanetetracarboxylate 18 as the main product and ethene- and ethanetricarboxylates as minor products. Acetylenemonocarboxylate is converted into the ethanetricarboxylate 19 as the main product with several other products[l8]. 

The propanedioate (malonate) carbanion can be oxidized directly at an anode to give ethanetetracarboxylate esters, presumably via a radical intermediate.2-4 Competing oxidation of solvent leads to a mixture of products3,4 and for preparative purposes it is advantageous to carry out the reaction via indirect electrolysis as reported here. Indirect electrolysis refers to the continuous generation and regeneration of a reagent at an electrode, which inter-... 

Tetramethyl 1,1,2,2-Ethanetetracarboxylate 1,1,2,2-Ethanetetra-carboxylic acid, tetramethyl ester (8,9) (5464-22-2)... 

Ethenetetracarboxylate esters may be reduced to the anion radical or stable dianion states depending on the cathode potential. Both have been used extensively as electrogenerated bases [84]. Interestingly, ethanetetracarboxylate esters do not give stable anion radicals but cleave to give the corresponding malonate anions [85]. 

Carbon-carbon single bonds may be cleaved when the two carbon atoms bear substituents that sufficiently stabilize the anions formed on the uptake of electrons to make them relatively weak bases. The reduction of ethanetetracarboxylate esters illustrates that these esters are reducible at rather negative potentials in DMFf-10% water at a mercury cathode at 60-65°C with splitting of the central carbon-carbon bond [3] ... 

Bischoff and Rach425 have described the preparation of tetraethyl 1,1,2,2-ethanetetracarboxylate in quantitative yield by the analogous reaction with iodine. 

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