Electrochemical Oxidations of Arylmethanes Investigated in Micro Reactors

3 Electrochemical Oxidations of Arylmethanes Investigated in Micro Reactors Organic synthesis 85 [OS 85] Oxidation of4-methoxy toluene to 4-methoxy benzaldehyde 

The electrosynthesis of 4-methoxybenzaldehyde (anisaldehyde) from 4-methoxy-toluene by means of direct anodic oxidation is performed on an industrial scale [69]. Via an intermediate methyl ether derivative, the corresponding diacetal is obtained, which can be hydrolyzed to the target product. The different types of products - ether, diacetal, aldehyde - correspond to three distinct single oxidation steps. 

The change of content of these three products was monitored as a fimction of temperature, in the presence of conducting salt (0.1 M KF) or in its absence [69]. In the first case, a near linear increase for the ether and acetal was foimd, but not for the aldehyde, which remained constant. The contents of the first two compoimds were more than doubled. On adding no salt, the ether and acetal increased only slightly and the aldehyde decreased to some extent, probably due to oxidation. 

---