Dieter Degner

Indirect electrochemical side-chain oxidation of alkyl aromatic compounds - selective synthesis of methyl benzoates or ortho-benzoic acid trimethylesters

Abstract The technically important side-chain oxidation of alkyl aromatic compounds to from either methyl benzoates or orthobenzoic acid trimethylesters can be performed electrochemically at low potentials in methanol solution using an undivided cell and tris(2,4-dibromopheny1)amine as redox catalyst. Under neutral or slightly acidic conditions methyl benzoates are selectively formed while under basic conditions the ortho-esters are predominating. In a similar way ortho benzoic acid trimethylesters are formed selectively starting from benzaldehyde dimethylacetals. The redox catalyst is stable under the reaction conditions so that several thousand cycles can be performed without noticeable loss.

Indirect electrochemical α-methoxylation of aliphatic ethers and acetals ― reactivity and regioselectivity of the anodic oxidation using tris(2,4-dibromophenyl)amine as redox catalyst

Abstract The technically important α-methoxylation of aliphatic ethers and acetals to form mixed acetals respectively aldehydes or ortho-esters can be performed electrochemically at low potentials in methanol solution using an undivided cell and tris(2,4-dibromophenyl)amine as redox catalyst. The regioselectivity is usually considerably higher as compared with direct electrolysis in the absence of a catalyst. Especially valuable is the method for the regioselective methoxylation of secondary carbon atoms in presence of primary or tertiary ones and of the acetal carbon in 1,3-dioxolanes. The redox catalyst is stable under the reaction conditions so that more than thousand turnovers could be obtained.