Diethyl thiodiglycolate

The Hinsberg synthesis of thiophene derivatives describes the original condensation of diethyl thiodiglycolate and a-diketones under basic conditions which provides 3,4-disubstituted-thiophene-2,5-dicarboxylic acids upon hydrolysis of the crude ester product with aqueous acid. ... 

Figure 4.13 Synthesis of monomer sulfonated 3,4-ethyledioxythiophene. 1 thio-glycolic acid, 2 diethyl thiodiglycolate, 3 diethyl 3,4-dihydroxythiophene-2,5-dicarboxylate disodium salt, 4 diethyl 3,4-dihydroxythiophene-2-5-dicarboxylate, 5 diethyl 2-(hydroxymethyl)-2,3-dihydrothieno[3,4-b][l,4]dioxin-5,7-dicarboxyl-ate, 6 diethyl 2-(hydroxymethyl)-2,3-dihydrothieno[3,4-b][l,4]dioxin-5,7-dicarbo-xylic acid, 7 2,3-dihydrothieno[3,4-b][l,4]dioxin-2-yl methanol, 8 sulfonated 3,4-ethylenedioxythiophene. (Reprinted from journal of Electroanalytical Chemistry, 443, O. Stephan, P. Schottland, P. Y. Le Gall, C. Chevrot, C. Mariet, M. J. Carrier, 217. Copyright (1998), with permission from Elsevier.)...

Hydrogen chloride was bubbled in a solution of thiodiglycolic acid (2 mol) dissolved in 810 ml methyl alcohol for 30 minutes, the solution stirred 16 hours at 27 °C, and the mixture concentrated. The residue was dissolved in diethyl ether, washed with brine, NaHC03 solution, dried, distilled, and the product isolated in 64% yield. H-NMR data supplied. 

Diphenyl sulphoxide, thiodiglycol sulphoxide, and diethyl sulphoxide are oxidised to the corresponding sulphones. Howard and Levitt studied the kinetics of oxidation of these compounds at pH 8 in a phosphate buffer (aqueous solution) and found the rates to be first-order with respect to peroxodisulphate and independent of the substrate concentration over the limited range employed (0.01-0.02 M). The removal of oxygen had no effect on the rate. Diethyl sulphide is oxidised very rapidly initially, then at the same rate as diethyl sulphoxide. Howard and Levitt concluded that the sulphide is first oxidised to the sulphoxide which in turn is oxidised to the sulphone, but Wilmarth and Haim point out that this interpretation cannot be correct, and conclude that the reaction must be more complex. 

---