for the following products
2,5-Dicarboxylic acid-3,4-ethylene dioxythiophene | 3,4-Ethylenedioxothiophene-2,5-dicarboxylic acid | Thieno[3,4-b]-1,4-dioxin-5,7-dicarboxylic acid-2,3-dihydro and 2,3-Dihydro-thieno[3,4-b]-1,4-dioxin-5,7-dicarboxylic acid
