3,4-Ethylenedioxythiophene (EDOT) and its derivatives contained hydroxyl groups are good blocks for the synthesis of the functional molecules based on EDOT. However, the products of the reaction between dimethyl 3,4-dihydroxy-thiophene-2,5-dicarboxylate (1) and epibromohydrin via Williamson etherification were a mixture of dimethyl 2'-hydroxymethyl-3,4-ethylendioxy-thiophene-2,5-dicarboxylate (2) and dimethyl 2'-hydroxypropyl-3,4-dioxythiophene- 2,5-dicarboxylate (2'), which is difficult to separate. Dimethyl 2'-iodomethyl-3,4-ethylendioxy-thiophene-2,5-dicarboxylate (3) and dimethyl 2'-iodopropyl-3,4-dioxythiophene-2,5-dicarboxylate (3') as well as 3,4-ethylendioxy-2'-hydroxymethyl-thio- phene (4) and 3,4-dioxy-2'-hydroxypropyl-thiophene (4') were synthesized by using the mixture. They are still mixtures and difficult to separate. It is very surprising that when an etherification reaction between the mixture (3+3') and cyanoethyl-carried tetrathiafulvalene (TTF-1) was conducted, the reaction showed highly selectivity, i.e., only 3 could react with TTF-1. The same situation happened when an esterification between the mixture (4+4') and carboxylic acid carried tetrathiafulvalene (TTF-3) was made, only 4 could react with TTF-3. Both the reactions afforded a single product, i.e., EDOT-TTF 1 and EDOT-TTF 2, respectively, whose chemical structures were characterized by ¹H NMR, ¹³C NMR, MS, and HRMS.

Key words: 3,4-ethylendioxythiophene, tetrathiafulvalene, esterification, etherification, selectivity