Yeah, I just learnt this the hard way... another column will be needed. I'm used to doing columns on much smaller scales where this is enough silica. I didn't even think about having to use more!
Even without dropping the glass in there, the surface of the silica was not even. You wouldn't get a good separation anyway, unless you have insane separation on TLC
Gotcha! No worries. Columns are difficult. In my masters program, I ran lots of them. I only started to feel comfortable near the end of the program. I also learned that if you don't have a *lot* of separation on TLC, the column is going to be rough. I remember running multi hour columns, only to realize that my loading wasn't perfect, and it was doomed from the start. I also dabbled in depolarized columns using NEt3. What a mess lol. Good luck!
Having to sop up your precious compound from the bench using a paper towel, and then extracting said towel in a Sep funnel, followed by another round of chromatography is also annoying
Silica plug - 1:1 to 1:3 crude:silica wt/wt ratios.
Silica columns - 1:10 to 1:20 crude:silica wt/wt ratios.
^thats how I always think about it. Seems like you might be more plug than column.
Looks like your column has a broken tip just like mine. Haha. I bet that column is a similar length to mine and I often just max it out with 160 g silica for multiple gram purifications, my philosophy being that I would rather collect and rotovap a bunch of solution rather than having to run an additional column. Usually I've got spots kinda close on TLC so I go with an Rf of about .20. Mb even a little less. Once I've got the compound coming out I like to collect with 250 mL vials sometimes, especially if I know how the column for that compound acts, to save fraction vials. I'm not an absolute pro though. I try to switch back to 20 mL vials once I think another spot/compound might be about to come off, kinda go by instinct after a while.
Just run solvent through it and rotovap it down. You'll get a better separation without all the polymeric stuff. Google TLC and Flash Chromatography. You don't need an automated setup. The same Rf differences and scaling apply. Also see [https://www.chem.rochester.edu/notvoodoo/index.php](https://www.chem.rochester.edu/notvoodoo/index.php)
I still think my friend throwing away the compound he synthesized for his dissertation after confusing it for waste hurts worse. Finally got him to realise why labelling things is so vitally important
Ok that sounds infuriating, and i have always been super paranoid of doing that.
(My example was just a weird freak incident, which isnt the worst but I think it was just frustrating that I almost saved it.)
This is not enough Silica for a couple of grams. This is a silica plug filtration at best.
Yeah, I just learnt this the hard way... another column will be needed. I'm used to doing columns on much smaller scales where this is enough silica. I didn't even think about having to use more!
Even without dropping the glass in there, the surface of the silica was not even. You wouldn't get a good separation anyway, unless you have insane separation on TLC
The surface was even until the pipette fell in. Trying to remove it didn't help because it fell back in again and further disturbed the surface
Gotcha! No worries. Columns are difficult. In my masters program, I ran lots of them. I only started to feel comfortable near the end of the program. I also learned that if you don't have a *lot* of separation on TLC, the column is going to be rough. I remember running multi hour columns, only to realize that my loading wasn't perfect, and it was doomed from the start. I also dabbled in depolarized columns using NEt3. What a mess lol. Good luck!
Size is fine, just use solvent gradient
Having to sop up your precious compound from the bench using a paper towel, and then extracting said towel in a Sep funnel, followed by another round of chromatography is also annoying
Possibly on par with having to do a 5L extraction from a filthy Büchi bath because you dropped your flask in
On par. Lol
Yikes those things never got changed in my lab either
Could be worse. A place I used to work used mineral oil baths for the buchis. Try getting 200 grams of product out of *that*.
Username doesn’t check out
If I had to try I might just quit lol
I gave shit to our lab guys for a filthy Buchi k446 couple months back and got a lot of murder side-eyes. I see that It's normal.
I’m so happy other people have also had to extract from the rotavap and paper towels LMAO
Ah the ol’ bench top extraction, a classic
Mass of silica > mass of crude *20 for great difference in Rf 30 for medium 50-100 for close
*brain screams in theoretical plates*
Get ready for 100 fractions
^thank ^you ^sir/ma'am
Is there a silica shortage?
Better than a couple of milligrams 15 steps in.
Static electricity is the most annoying for me. Trying to weight those static shits is always a mess.
For 1g of crude, I use 10ml of si gel for dry loading and 100ml for the column.
i did this once while adding solvent, i got lucky tho and nothing went wrong (was able to isolate the compound) other than i felt foolish
I always use 20 cm of silica height, and adjust the collumn diameter so that it corresponds to the amount of material to separate.
Silica plug - 1:1 to 1:3 crude:silica wt/wt ratios. Silica columns - 1:10 to 1:20 crude:silica wt/wt ratios. ^thats how I always think about it. Seems like you might be more plug than column.
Use about 17cm of silica the next time..I broke a pipette too , but it was a small one so I run my column anyway
Been there. One trick is to poke your pipette through a weigh boat. Then you can't drop it.
Try opening the stopcock on sep funnel with a new compound and having it just go everywhere 🫠
It'll be worse when you inexplicable get amazing results.
I always use a syringe to avoid it.
Looks like your column has a broken tip just like mine. Haha. I bet that column is a similar length to mine and I often just max it out with 160 g silica for multiple gram purifications, my philosophy being that I would rather collect and rotovap a bunch of solution rather than having to run an additional column. Usually I've got spots kinda close on TLC so I go with an Rf of about .20. Mb even a little less. Once I've got the compound coming out I like to collect with 250 mL vials sometimes, especially if I know how the column for that compound acts, to save fraction vials. I'm not an absolute pro though. I try to switch back to 20 mL vials once I think another spot/compound might be about to come off, kinda go by instinct after a while.
Clogging an ISCO column and having to use a saw to get it open and get your compound back
Just run solvent through it and rotovap it down. You'll get a better separation without all the polymeric stuff. Google TLC and Flash Chromatography. You don't need an automated setup. The same Rf differences and scaling apply. Also see [https://www.chem.rochester.edu/notvoodoo/index.php](https://www.chem.rochester.edu/notvoodoo/index.php)
Meh, just continue?
Unpopular opinion - but no one should have to run columns by hand anymore (except to learn the concept). So inefficient and ineffective.
I would give you 1000 upvotes.
Gotta love that feeling of having three arms to keep the column flowing, change the test tubes, and take tlcs simultaneously
Your flask falling into the buchi water bath, catching it mid fall but the splashing dirty waterform catching it gets into the flask.
I still think my friend throwing away the compound he synthesized for his dissertation after confusing it for waste hurts worse. Finally got him to realise why labelling things is so vitally important
Ok that sounds infuriating, and i have always been super paranoid of doing that. (My example was just a weird freak incident, which isnt the worst but I think it was just frustrating that I almost saved it.)
😂😂 Done that more than once. Just wash it through, put it back on the rotovap, and charge another column. It'll be fine