Abstract: 3,4-Dialkoxythiophenes are electron rich and their polymers have a narrow energy gap, so they have recently attracted considerable attention in the field of organic semiconducting materials. However, the traditional synthetic approach suffers from some drawbacks, so the development of efficient methods for the synthesis of 3,4-dialkoxythiophenes is needed. A novel, efficient decarboxylation of 2,5-dicarboxy-3,4-dialkoxythiophenes was achieved in excellent yields (up to 95%) and purities using metal phthalocyanines in water, which avoids the use of organic polar solvents, and the recovered catalyst was successfully used in subsequent reactions. Furthermore, the desired products, 3,4-dialkoxythiophenes, were conveniently separated by steam distillation. This method has several advantages such as environmental friendliness, ease of manipulation, and a short reaction time. This environmentally friendly procedure represents a promising green route for the decarboxylation of these important compounds.

Key words: decarboxylation, 3,4-dialkoxythiophene, phthalocyanine, synthesis, green chemistry