(note: this is a reposting of part of my original post which I was told had too many questions in one post)

Please bear with me as I am a chemistry newbie, but I am autistic and have recently developed a fixation on electrosynthesis and must understand it.

I'm interested in split reaction systems, where a salt bridge connects two chambers, and an aqueous media is used. I'll try to split my questions about this into two sections; water alone, and organic synthesis that take place in water.

In the anode chamber, with the use of a catalytic anode (platinum, platinized titanium, palladium, etc), will the free radicals form hydroxides, peroxide, etc. just build up if the water is stirred properly? Or will ions coming across the salt bridge balance it out somehow? I am confused about that because I thought the point of the salt bridge is to isolate half reactions. So I assume you get unbalanced results isolated in each chamber?

When you add a complex organic molecule, how do the electrochemists keep the side-reactions from trashing their molecules? Do they have to factor in the water reactions as part of their strategy to reduce or oxidize the compound?

  • $\begingroup$ You lost me in "will the free radicals form hydroxides, peroxide, etc. just build up if the water is stirred properly". Also, "when you add a complex organic molecule"? Add to what? $\endgroup$ – It's Over Jul 8 '16 at 14:33
  • $\begingroup$ As potential is developed between the electrodes, the water itself forms acids and alkali at the cathode and anode respectively. These in situ reagents are what I am talking about. They only form near the electrodes, so the media(water), must be stirred somehow. At high enough voltage the bubbling of escaping hydrogen and the formation of the aforementioned reagents stirs for you. In regard to the complex organic molecule, I am talking about adding it to the water. I'm just restricting it to water to keep it simple, but I do know that redox reagents are used to facilitate some reactions. $\endgroup$ – Dangus McFinghin Jul 8 '16 at 16:26
  • $\begingroup$ How do I get this question taken off of hold? Everything I have posted so far has been appropriate and friendly(though apparently unclear), but I have not had a very welcoming experience here so far. $\endgroup$ – Dangus McFinghin Jul 8 '16 at 21:41
  • $\begingroup$ It would have to be heavily edited. $\endgroup$ – Mithoron Jul 9 '16 at 18:42
  • $\begingroup$ I'm trying to figure out how to just get rid of my account, but its not nearly as easy as it should be. $\endgroup$ – Dangus McFinghin Jul 11 '16 at 4:11

You're right, a salt bridge is used to isolate the reactants but still to allow charge to flow. For example, in the case of a Sodium Chloride Salt Bridge, Sodium ions will flow into one chamber while the Chloride will flow into the other. Overall the system must stay charge neutral.

If the system contains water only, on both sides, then what will happen is that you will electrolyze the water and get $\ce{H2}$ and $\ce{O2}$ gas.

As for complex organic molecules, I believe when oxidizing or reducing them the preference is to use chemical reagents instead of electrolysis.

  • $\begingroup$ Thanks for your response. That is much the way I was imagining it, but I am still a bit unclear on how this doesn't result in sodium, potassium, or whatever from becoming part of your finished product. It seems like there is a lot of research going on in Asia, and they even sell machines for complex electrosynthesis that they claim are capable of working CO2 up to complex hydrocarbons. I read a book about this subject that was written in the late 1800s by Walther Löb, and it seems to me like this area of research may have been neglected a bit during a time of cheap petrochemicals... $\endgroup$ – Dangus McFinghin Jul 8 '16 at 6:45
  • $\begingroup$ @DangusMcFinghin Book from 19th century? Get some textbook not ancient stuff. $\endgroup$ – Mithoron Jul 9 '16 at 18:46

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