The Preparation of 3,4-Dimethoxy-2,5-dicarbethoxythiophene. 3,4-Dimethoxythiophene

The synthesis and properties of novel diazo chromophores based on thiophene conjugating spacers and tricyanofuran acceptors

“…The Type 2 compounds possess 3,4-dialkoxythiophene-based bridges. The synthesis of 3,4-dibutyloxythiophene (11) was accomplished following the general procedures outlined in the literature (Scheme 3) [9]. Diethyl thiodiglycollate (8) was obtained by Williamson ether reaction of sodium sulfide with ethyl chloroacetate [10].…”

“…The Hinsberg condensation between compound 8 and diethyl oxalate afforded 2,5-dicarbethoxy-3,4-dihydroxythiophene (9) [11]. In our procedures, compound 9, anhydrous potassium carbonate (K 2 CO 3 ) and 1-bromobutane reacted quantificationally in the solution of N,N-dimethyl formamide (DMF).…”

“…The solution was refluxed and acidified to afford 3,4-dibutyloxy-2,5-thiophenedicarboxylic acid (10). 3,4-Dibutyloxy-thiophene (11) was obtained from the decarboxylation reaction by heating compound 10 to 220 C under N 2 atmosphere for 2 h [12].…”

“…4.2.7. 2, [11] To a solution of sodium ethoxide prepared by adding sodium metal (7.0 g, 0.30 mol) to absolute ethanol (150 ml), a mixture of compound 8 (16 g, 0.13 mol) and diethyl oxalate (19 g, 0.13 mol) was added dropwise over 30 min. After the addition, the mixture was refluxed for additional 2 h, and then cooled to room temperature.…”

Nonlinear optical studies on new conjugated poly{2,2l‐(3,4‐ dialkoxythiophene‐2,5‐diyl) bis[5‐(2‐thienyl)‐1,3,4‐oxadiazole]}s

“…They were purchased commercially and used without further purification. Diethyl 3,4‐dialkoxythiophene‐2,5‐dicarboxylates were synthesized according to the reported literature procedure 17–19…”