Syntheses in the Thiophene Series

SUMMARY The Friedel-Crafts reaction has been used in the preparation of thiophene ketones, some of which were hitherto unknown. Certain limitations of the reaction have been noted. The mercuration of thiophene ketones has been systematically investigated for the first time. Many new halogen derivatives of benzothienone have been synthesized. These were employed in the elucidation of the structure of a complex mercurial· derived from this ketone. A new modification of an old reaction has been developed whereby benzothienone can be mercurated quickly and almost quantitatively. Interesting derivatives of this little known ketone have been synthesized. Chief among these are the previously inaccessible arsenicals, reasonably stable, well defined substances, which should merit further consideration. The mercuration of acetothienone is complicated by the presence of the reactive alpha hydrogens of the side chain. Although several mercurials have been obtained, true aromatic substitution has not been achieved successfully. The fact that two mercurials have been prepared from nitrothiophene is contrary to the observation of an earlier investigator who said, 2-Nitrothiophen mit Sublimat reagieren nicht