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Just watched a tiny pinhole leak in a cannula transfer kill an entire afternoon of work, and I need to vent before I go reset the Schlenk line.
Doing organometallic or moisture-sensitive chemistry is a completely different level of paranoia. The paper will casually say "all manipulations were carried out under an atmosphere of dry argon," but they completely skip over the two hours of flame-drying glassware, degassing solvents, and praying your septa don't degrade mid-transfer.
My personal list of inert-atmosphere misery:
Whenever I see "filtered through a medium-frit Schlenk funnel" in a paper's supporting info, I know someone spent three hours fighting a clogged frit under positive N2 pressure.
What’s the one air-sensitive maneuver or Schlenk setup that instantly makes you dread setting up a reaction?
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Regarding the last point: This is why you always have a Karl Fischer system available if you are insisting on SPS instead of properly maintained solvent stills.
Also it’s generally safe to assume the SPS THF is still a little wet. Treat it like a pre-purification because using a drying agent on off-the-shelf THF is even more a pain in the ass (and prone to polymerization).
Anything that is in immediate danger of exploding in contact with air, really keeps my butthole clenched
I hate any kind of air-sensitive filtration. Swivel frits are one technique I have never learned, but it's the kind of thing an expert makes look easy, that I'm sure would go south quickly in my hands.
While this isn’t air-free technique in the purest embodiment I nevertheless always get heebie jeebies when a procedure includes vacuum filtration in order to separate a solid catalyst like Raney Nickel or palladium on carbon from the extremely flammable and possibly explosive organic reaction mixture… nothing will snap a chemist out of an absentminded stupor like the sight of a shower of pyrophoric sparks threatening to repurpose their reaction mixture into a borosilicate glass fragmentation grenade & molotov cocktail combination! Be sure to never let a highly active solid catalyst run dry when performing vacuum filtration.
Organic chemist of 33 years here. I’m at the point where I just say to myself “Nope, that sounds like a lot of trouble.”
1) Having to silylate your glassware because it degrades if you don’t. 2) light sensitive and air sensitive 3) ether soxhlet (hot ether dissolves the grease on the joints)
Distilling pyrophoric metal compounds. Need such a gargantuan setup and it’s terribly sensitive.
Also, any large challenging maintenance on my glovebox gives me a scare. Don’t want to break my big expensive toys
100% cannula transfers. I did a lot of my undergrad and all of my grad work under schlenk or glovebox conditions and having a cannula clog or being worried about the tension in the needles causing trouble somewhere... Ugh
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As an inorganic chemist, y'all are just whining. Schlenk work was my daily bread and butter, and if you do it right, there's nothing to be so anxious about. I ran a lot of reactions where my goal was to bind dinitrogen to metal-metal bonded complexes that were exceptionally ligand-hungry. I couldn't run the reaction on dichloromethane, because even that was somehow oxidizing the complex. Within the schlenk glassware, I filtered the product dissolved in dichloromethane directly into a tube kept at -80 C. I layered hexanes on top, and after a month in the -80 C freezer, there were crystals. I then harvested those crystals under a stream of Argon, mounted them on the diffractometer, and collected a crystal structure that ended up being a dichloromethane adduct. I ultimately had to design a ligand system that made these complexes soluble in alkanes, and try to generate these complexes there, in the absence of anything that could possibly coordinate, including barely coordinating solvents, oxygen, water, grease, etc. I finally was able to grow crystals in decane, and you know what was at the binding site? Still no N2. It was a C-H bond of decane, datively bound to the metal site. Crazy, right?
This really is a case of “the more you do it, the less of a big deal it is” I’ve been doing Schlenk line chemistry for a lot longer than I didn’t do it before learning about it. It’s almost harder for me to just setup an open air reaction now because my default is to use the technique. I exaggerate slightly, but you get the point.
To address your first point: I have been using this PTFE tubing in lieu of metal needle cannulas for years. You can buy it in different diameters to alleviate slurry clogging issues and it’s cheap enough to be disposable so you don’t risk contamination from one system to the next. Also, it’s PTFE so compatibility is seldom an issue with anything. It takes a bit of practice to get the cannula through your septa, but once you get the technique down there is no going back. I don’t remember the last time I used a metal cannula. https://www.coleparmer.com/p/cole-parmer-ptfe-tubing/88324
Really the only one that gives me pause is doing a low-temperature Shlenk filtration, e.g. with a swivel frit. It’s a big assembly of glassware, the filtration has to happen quickly to avoid decomposition (so a cannula filtration is out), and the process usually takes up most of the taps on the manifold. It’s one of the few truly time-sensitive operations where everything needs to go smoothly or you just have to start over. But to address your issues: 1) use a larger 5-10mm ID HDPE or PTFE tube instead of a <16G cannula for slurry transfers 2) Get yourself a Po strip ionizer and weigh out on folded squares of Al foil instead of paper, 3) I always use freshly-snipped Mg ribbon so there’s no passivation layer to fight through for initiation (ribbon>turnings>powder), 4) trust but verify, verify, verify.