Tetraketones of the type 3,4-diaroyl-2,5-hexanedione: Ar
= CsH;-, p-CHs-CsH4-, 3,4-(CHsh-CsHs-, p-CHaO-CsH4-, p-
Cl-CsH4-, p-Br-C6H4- and 2-C4H3S- were prepared in good
yield by oxidative anodic dimerization of aroylacetones. Electrochemical
oxidation was carried out at constant current (4-5 A)
in cylindrical cell without diaphragm with Pt-gauze anode and
Ni-cathode. Depending on the method used (A or B) and depending
on the properties of the electrolysed aroylacetones, dimer-products
were isolated as stable keto or enol tautomers. Electrolysis in 80°/o
aqueous methanol (Method A) gave keto or enol tautomers, while
electrolysis in absolute methanol (Method B) yielded only enol
tautomers
