Saturday, August 15, 2015

Cellphone Charger Electrochemistry

I'm frankly amazed at chemists' rugged pragmatism. Our ilk often repurpose seemingly innocent household items - floodlights, LED strips, paraffin wax - adapting them for making new molecules in interesting ways. Have a peek at this new paper, which appeared* last week in Angewandte Chemie. 

The Aubé group, recently of UNC, wondered whether expensive setups from scientific vendors were potential roadblocks to wide adoption of electrochemistry. Their ideal recipe called for a direct current (DC) source capable of removing two electrons and an H from a lactam to generate an N-acyliminium ion. Looking around, the researchers realized that today's ubiquitous cellphone chargers might just do the trick. Shave back some wires, attach some copper clamps, and presto! Cheap, effective electrochemistry.**




Using their DIY e-chem setup, the Aubé group traps a wide variety of stereochemically-rich acyliminiums as the corresponding methanol adducts (19-93% yields). Now the real fun starts: there's a whole bunch of interesting arylations and other additions to these species one can access using off-the-shelf Lewis acids like titanium tetrachloride or boron trifluoride:

Adapted from Aube, Angewandte Chemie, 2015 ASAP

I'll be excited to see small libraries of diversified products emerge from this work. However, a "one-pot" functionalization - electrochemistry with the desired nucleophile already present - still seems a distant dream.

Hopefully, the apparent ease of operation of "cellphone charger e-chem" prompts other groups to give it a try. If your group dips their toes into this field, please drop me a line in the comments section.

--
*Thanks to Professor Brandon Findlay (@Chemtips) for pointing out this paper!

**I'm tickled pink at how many organic synthesis papers these days include photographic records of reaction setups. I'd like to believe that Blog Syn played a small role in advancing this change.

8 comments:

  1. I am currently (pun intended) working on a setup that can build Ag/AgCl electrodes without taking up one of our potentiostats. All I need is a 1.5V DC source that can source about 1A of current, so I am going to use a simple DC-DC step-down converter from one of these ubiquitous chargers, with the intention of building a SMPS dedicated setup at some point in the future.

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    1. Use a single AA cell. As soon as your silver electrode is connected, the electrical resistance will increase dramatically. A simple wire electrode will stabilize within seconds at under a milliamp, so a single AA cell will make several dozen electrodes.

      If you really want to build a 1.5V supply, do your research carefully. Many regulator circuits do not function well at such a low voltage.

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  2. Phil Baran has demonstrated the use of a camping battery for electrodes in oxidations, in his seminar this morning at ACS Boston.

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    Replies
    1. You could even say I was live-tweeting him as he went ; )

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  3. Oh yeah? Sorry I missed that. And I was surprised there hasn't been more banter about the conference on your blog, guess I missed it over on Twitter. I haven't taken the plunge and signed up for an account yet.

    ReplyDelete
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    ReplyDelete
  5. I like the botton view.

    ReplyDelete