tag:blogger.com,1999:blog-51846086760422068.post7670507704386752847..comments2024-03-28T08:37:08.964-07:00Comments on Open Flask: C–H Oxidation Meets ElectrochemistryBaranLabhttp://www.blogger.com/profile/01806245988209508968noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-51846086760422068.post-22564318799105377582017-02-14T08:10:17.046-08:002017-02-14T08:10:17.046-08:00Nice job ! :) Please can I have the reference of y...Nice job ! :) Please can I have the reference of your potentiostat asymchem? Thanks !Anonymoushttps://www.blogger.com/profile/07698429597906611715noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-19680253695449961682017-02-14T08:07:30.678-08:002017-02-14T08:07:30.678-08:00This comment has been removed by the author.Anonymoushttps://www.blogger.com/profile/07698429597906611715noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-9348024143556228532016-05-27T08:16:36.462-07:002016-05-27T08:16:36.462-07:00Perfect! Thank youPerfect! Thank youUnknownhttps://www.blogger.com/profile/03969277260971572876noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-37314698378041919482016-05-26T13:13:54.593-07:002016-05-26T13:13:54.593-07:00Yeah, soldering the wire can be a little tricky, a...Yeah, soldering the wire can be a little tricky, as the solder does not stick to the carbon well. The trick is that you do not want to melt the solder by directly putting the solder to the tip of the soldering iron, but rather use the soldering iron to heat up the wire/RVC until the wire is hot enough that it melts the solder. This way both interfaces are hot and the solder can flow into the cracks and pores of the electrode/wire. After a small amount of solder has melted, I jiggle the wire a little bit until the ball of solder drops into the hole that the wire is in, and then I keep the soldering iron on the wire for a little bit longer to make sure the solder really flows into the pores. If you just have the drop of solder on the top of the electrode, it will not hold, it needs to really be inside that hole where the wire is (the hols goes in ~3-4 mm). This takes a little bit of practice but once you get it down it is quite easy.<br /><br />For wire, make sure you are using some sort of wire that is braided or spun so that there is more cracks and surface area for the solder to stick to. If you just use straight gauge wire it will be difficult to get the solder to make a solid mechanical connection that will not easily pull out. Picture hanging wire works well for this, and can easily be purchased at any hardware/framing/craft store. Just make sure it is stainless steel so that it is a little more resistant to corrosion. Hope this helps! If you still have trouble please contact me directly and we can try to work something out. <br /><br />Evan Anonymoushttps://www.blogger.com/profile/13659802314538040593noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-76838441261113690592016-05-26T07:17:33.327-07:002016-05-26T07:17:33.327-07:00Do you have any tips for soldering the RVC electro...Do you have any tips for soldering the RVC electrodes? My solder keeps balling up and falling off. Also- what gauge SS wire did you use? Thanks!Unknownhttps://www.blogger.com/profile/03969277260971572876noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-40526811947419940172016-04-28T10:17:31.320-07:002016-04-28T10:17:31.320-07:00Thank you!Thank you!Unknownhttps://www.blogger.com/profile/03969277260971572876noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-2444534284960870472016-04-28T08:56:38.935-07:002016-04-28T08:56:38.935-07:00The reactions can take anywhere from 8 to over 24 ...The reactions can take anywhere from 8 to over 24 hours to go to completion. Anonymoushttps://www.blogger.com/profile/13659802314538040593noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-9726885353808738322016-04-27T16:35:46.438-07:002016-04-27T16:35:46.438-07:00How much time did the reactions take to go to comp...How much time did the reactions take to go to completion (a range of values is fine)? Thanks!Unknownhttps://www.blogger.com/profile/03969277260971572876noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-16023857249682613492016-04-21T12:38:16.103-07:002016-04-21T12:38:16.103-07:00I see what you are thinking, but we are pretty sur...I see what you are thinking, but we are pretty sure that the ppt is some sort of pyridinium or NHPI salt. We had tried NaClO4 but due to the lower solubility it did not work as well. We also don't think that the electrodes are being oxidized to carbonate, since glassy carbon is extremely resistant to oxidation and the potential is not high enough. Thanks for the ideas though!Anonymoushttps://www.blogger.com/profile/13659802314538040593noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-6117976552364495842016-04-20T18:18:36.309-07:002016-04-20T18:18:36.309-07:00last thing: the salt buildup on cathode. One possi...last thing: the salt buildup on cathode. One possible candidate is lithium carbonate - it has low solubility. (The carbonate would come from oxidative degradation of anode but Li2CO3 would precipitate on cathode because of high local concentration of Li+).<br />If it is Li2CO3 that precipitates on cathode, maybe switching from LiClO4 to NaClO4 would solve this problem, sodium perchlorate solubility in acetone is less than of Li-perchlorate (0.52g dissolves in 1mL of acetone, vs. 1.37g/mL for Li perchlorate) but it might be still good enough for your purposes.milkshakehttps://www.blogger.com/profile/08188961610554710616noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-7339411361754645442016-04-20T16:52:50.099-07:002016-04-20T16:52:50.099-07:00Thanks for the suggestion, we will look into that!...Thanks for the suggestion, we will look into that!Anonymoushttps://www.blogger.com/profile/13659802314538040593noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-20112632688356034942016-04-20T16:47:08.501-07:002016-04-20T16:47:08.501-07:00sorry bothering you one more time: please have you...sorry bothering you one more time: please have you tried some more electron deficient analogs of HOBt, namely HOAt with pyridine ring? It is more acidic and has very good solubility, its anion is yellow... The material is explosive on large scale but as very fluffy cotton-like solid it does not pose much hazard. Advanced Chemtech has it for a good price (CAS# 39968-33-7) and unlike tetrachloro-NHPI it is a very polar compound with a small molecular weight.milkshakehttps://www.blogger.com/profile/08188961610554710616noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-48994006911578730592016-04-20T16:29:07.003-07:002016-04-20T16:29:07.003-07:00Thanks! In general this reaction is no more differ...Thanks! In general this reaction is no more different to purify than a non-electrochemical reaction, the lithium perchlorate is simply removed in the aqueous wash. The reaction is not completely homogeneous since the Cl4-NHPI•pyridinium salt is not completely soluble so that accounts for the dark color of the solution. As far as carbon colloids, glassy carbon/RVC is extremely inert so I do not believe that the electrolysis decomposes the electrodes at all. However, the RVC foam is fairly brittle so sometimes the stir bar can grind away some of the electrode and you get bits of it in the reaction, but this doesn't seem to be a problem. <br /><br />When we were using graphite electrodes, we did use toluene to extract the starting material/product from the electrodes, this worked better than more polar solvents and better than hexane, but we still were unable to recover all the material. For some of the more volatile substrates this is an issue since you loose a lot of the product removing the toluene. <br /><br />The solvents that we found to work for the reaction were acetone, MeCN, DCM and pyridine. Other less polar solvents like toluene and hexane didn't work since we could not get enough of the LiClO4 or LiBF4 electrolyte dissolved so the reaction is unable to pass current. Etherial solvents also didn’t work, and we suspect this is because they undergo competing C–H abstraction from the pthalimide radical. <br /><br />In theory we could use a number of other materials for the cathode in this reaction; however, one thing that we did not go into detail in the paper is the fact that there is salt buildup on the cathode that increases the resistance of the cell and eventually insulates it to the point that current is unable to pass. We get around this issue by alternating direction of the current every 15 minutes (so that the anode becomes the cathode and vis versa). This causes the salts to slough off and the current to remain more stable. <br /><br />Thanks for the questions!Anonymoushttps://www.blogger.com/profile/13659802314538040593noreply@blogger.comtag:blogger.com,1999:blog-51846086760422068.post-27002999796676795042016-04-20T15:23:17.754-07:002016-04-20T15:23:17.754-07:00This is really nice, for too long electrochemistry...This is really nice, for too long electrochemistry was the last method a natural product synthetic chemist would use - Your group has been leading the renaissance. But as a chemist who never used any electrochemistry, I wanted to ask you - how difficult is to purify the reaction mix from the perchlorate electrolyte and other additives (compared to traditional reaction mix)? Also, I noticed the reaction mix looks dark - do you get any carbon colloids from the electrodes? Also, for releasing any product stuck on graphite electrodes - please have you tried addition of a greasy solvent like toluene or xylenes? Also, is the absorption on carbon electrode surface important to the anodic oxidation (i.e. does the reaction work better in highly polar solvents rather than in more lipophilic ones)? Does the cathode have to be from RVC carbon foam, or would some common metal (i.e. titanium) also work for the purpose?milkshakehttps://www.blogger.com/profile/08188961610554710616noreply@blogger.com