Sciencemadness Discussion Board

Recrystallize inside a Fritted Jacketed Buchner Funnel without Pouring?

LuckyWinner - 20-5-2021 at 07:47

someone is selling a used jacketed glass fritted disk containing buchner funnel.

4/5 of the volume is above the fritted disk.
1/5 of the volume is under the fritted disk.

is this a good method to recrystallize in the same flask
without pouring?

A solid which is dissolved inside a recrystallization
solvent is added to this flask while

jacketed cooling liquid is slowly reduced by PID controller
to increase crystal size and purity.

question:
does this work or are these jacketed filters only
used for hot filtration's?

Problem?:
since 1/5 of the funnel is below the fritted disk.
this amount will precipitate below the disk and will
get drained once you filter the precipitate?

what the best way to recrystallize in the same vessel without pouring?

zinc finger - 21-5-2021 at 01:06

I used such a buchner funnel with cooling once before. I washed some crystals with a solvent that needed to be cold to limit the dissolution. It worked ok for this purpose. However I never saw someone recrystalising inside a buchner. I suppose if you make your collection flask air thigh, you can build up a positive pressure that could help preventing the solvent from going through the fritted disk and the lower volume would stay empty.

LuckyWinner - 21-5-2021 at 08:05

This is a quote from a 'chemglass filter reactor' , which is basically the same like a jacketed buchner funnel with fritted disk:

'https://chemglass.com/10l-jacketed-filter-glass-reactor-systems-electric-or-air-motor'
Quote:

Our jacketed filter glass reactors can be used for single or multi-step reactions and filtrations in the same vessel, production and process scale peptide synthesis. Filter base eliminates material transfers and significantly reduces losses. Complete reactor system on our NEW open air, autocenter stand. 150°C Max. Temp. Limit for Filter Base.

Please Note: Filter Reactors are for Vacuum/Gravity Filtration Use Only


they write
single or multi-step reactions and filtrations in the same vessel.
that means it is possible. but how to do it properly?
they use positive pressure?

but once you transfer the solvent inside the fritted buchner filter
it will permeate through the fritted disk immediately?

Fyndium - 21-5-2021 at 08:24

I wonder this too. Positive pressure should be the only method, and even still some liquid will likely leach due to capillary action. When you pour water into frit, it will slowly but steadily flow through, but less viscous stuff like acetone will readily, although still slowly, flow through it. With reasonable high vacuum, many liquids will just literally shoot through the frit.

LuckyWinner - 21-5-2021 at 14:39

the buchner with fritted disk will have a bottom valve
but that will not hinder the solvent from creeping through the disk.

the only option I can think off is getting a buchner funnel designed with little bottom clearance
below the fritted disk.
once you vacuum drain the solvent you dump it back into the top to partialy
recover the 1/5 bottom drainage...

but I did not see this technique in any large scale
reactor which is shown on youtube...