Thanks.
Yes, it seems okay, doesn't it? Except for the need for carbon monoxide.
I would think it might work with chlorobenzenes as well, and I guess one might possibly find some references to that in one of the citations in the beginning of the patent.
A patent I just mentioned in another thread,
Patent US4988416
seems similar, except electrolysis is used in place of the palladium-catalysis (dehydrogenation?), and here it also works with fluorobenzenes, chlorobenzenes and iodobenzenes in addition to the bromobenzene.
They use sacrificial anodes of your choice, either aluminum, zinc or magnesium. I don't know anything about sacrificial anodes other than that they dissolve with time. Whether less, equal to, or more than one molar equivalent of the metal is required, I don't know. It would be a bit expensive to have to use a mole of aluminum for every mole of benzaldehyde. Okay, maybe not "expensive", but polluting then.
It would be great if this worked with "inert" anodes, but tbey don't make that clear in the discussion in the beginning of the patent. They just say that other authors have gotten poor yields when using divided cells AND inert anodes (graphite), but there is no mention of the yields of using inert anodes and a non-divided cell (i.e., no porous barrier to protect against the cathode).