Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag₂CO₃ and Microwaves

Synthesis of bis-3,4-dialkoxythiophenes linked by a m-xylene bridge

“…The saponification reaction in refluxing ethanol 15 was applied to the bis-thiophenic derivatives 3a, and 8 in yields of 92% for R = H and 81% for R = CH 3 . The corresponding diacids 9 and 10 were submitted to protodecarboxylation reaction using a recently developed method, 16 catalyzed with Ag 2 CO 3 /AcOH system in DMSO using microwave heating, at 150 °C during and 15 min. Under these conditions yields of 80% for compound 11 (R = H), and 70% for compound 12 (R = CH 3 ) were obtained.…”

“…This method does not require the use of quinoline as a solvent, which is known to be a harmful and toxic substance and thus allows production of protodecarboxylation products in a cleaner way. 16 In order to avoid a poly-transetherification reaction the synthesis of 11 was conducted in low concentrations of 15. The first attempt with a 1:10 dilution provided 11 with 9% yield (entry 1, Table 3).…”

“…When, the concentration of 15 was elevated two-fold, the yield increased to 40%. In addition, in these conditions the 18 member cycle (16) was isolated in 5% yield. Longer reaction time (entry 3, Table 3) did not improve the results.…”

Highly Ordered Macroporous Poly-3,4-ortho-xylendioxythiophene Electrodes as a Sensitive Analytical Tool for Heavy Metal Quantification

“…All the solutions were prepared with deionized water (Milli-Q Direct-Q). The 3,4- ortho -xylendioxythiophene was synthesized in our laboratory following a published methodology for the synthesis of 3,4-alkoxythiophenes . The LB film formation and the deposition of the LB films onto cylindrical substrates were carried out as described previously. , A single compartment three-electrode cell, equipped with a templated or modified Au wire working electrode, a cylindrical Pt mesh as auxiliary electrode, and an Ag/AgCl (in 3 M KCl) reference electrode (Bioanalytical Systems), was used.…”

“…The silica template was formed by transferring 20 layers of silica particles ( d = 600 nm) onto the surface of a gold wire ( d = 0.25 mm), after initial O 2 plasma cleaning, by means of the LB technique. , Oxidation of XDOT (5 mM in a 0.1 M LiClO 4 /ACN solution) occurs via an irreversible process on the surface of the templated Au electrode, showing in the reverse cycle of the voltamperogram the typical trace-cross effect observed during the electrochemical polymerization of π-conjugated systems (Figure S1). A potential of 1.29 V vs Ag/AgCl was selected to perform the potentiostatic electropolymerization, as this value allows a homogeneous growth inside the template.…”