5‐Substituted Benzothiophenes: Synthesis, Mechanism, and Kinetic Studies

The kinetics of the reaction of 4-methoxythiophenoxyacetaldehyde diethyl acetal, 4-nitrothiophenoxyacetaldehyde diethyl acetal, and 3-methoxythiophenoxyacetaldehyde diethyl acetal in polyphosphoric acid has been explained. The kinetic behavior has been explained on the basis of aided simulation and on the basis of density functional theory calculations showing a different pathway for 4-nitrothiophenoxyacetaldehyde diethyl acetal and for 4-methoxythiophenoxyacetaldehyde diethyl acetal. In this last case, a very fast competing reaction to the dimerization product was observed.