Sciencemadness Discussion Board

Dimroth for Distillation

artemov - 19-8-2019 at 04:23

Can a condenser like this (Dimroth?) be used for distillation at an angle, as well as reflux?



https://www.ebay.com/itm/200mm-24-29-Glass-Coil-Reflux-Conde...

Cheers.

[Edited on 19-8-2019 by artemov]

teodor - 19-8-2019 at 05:41

I use Dimroth for distillation. There is only one small problem with fractional distillation (i.e., with a column) - it always keeps a few milliliters of previous fraction (this curved bend does it). For small fractions (<10 ml) it could be a problem so I use Liebig for them. But for larger fractions it's perfect - just wait till the liquid inside condenser is replaced by a new fraction and then start to collect it.

But I think this problem could also be fixed with 105 degrees distilling adapter to keep Dimroth in vertical position.

[Edited on 19-8-2019 by teodor]

artemov - 19-8-2019 at 05:56

Quote: Originally posted by teodor  
I use Dimroth for distillation. There is only one small problem with fractional distillation (i.e., with a column) - it always keeps a few milliliters of previous fraction (this curved bend does it). For small fractions (<10 ml) it could be a problem so I use Liebig for them. But for larger fractions it's perfect - just wait till the liquid inside condenser is replaced by a new fraction and then start to collect it.

But I think this problem could also be fixed with 105 degrees distilling adapter to keep Dimroth in vertical position.

[Edited on 19-8-2019 by teodor]


Thanks teodor.

Is a dimroth more fragile or difficult to wash than a liebig?

Would you think that for equivalent length, a dimroth is more efficient than a liebig? I suppose for reflux, a dimroth would definitely be better than a liebig.

I have the option of topping up $5 in my distillation kit purchase to change a 200mm liebig to a 200mm dimroth (shown above).

Sulaiman - 19-8-2019 at 05:57

If you buy one of these (or similar)
adapter.jpg - 170kB
then you can use just one stand as everything will be vertical.

P.S. the Dimroth is MUCH more efficient than a Leibig.

[Edited on 19-8-2019 by Sulaiman]

teodor - 19-8-2019 at 06:52

Quote: Originally posted by artemov  

Is a dimroth more fragile or difficult to wash than a liebig?


Well, you can consider me as a newbie - I never broke either.

In theory you can wash Liebig with a brush, in case of Dimroth it is not possible. But practically I seldom have success with a brushing of Liebig so I use chromic acid for both. In some cases it could be cleaned by a reflux of solvent. So, don't see an advantage in Liebig as for washing.
Quote: Originally posted by artemov  

Would you think that for equivalent length, a dimroth is more efficient than a liebig? I suppose for reflux, a dimroth would definitely be better than a liebig.


I have 250 mm Dimroth and full condensation of gaseous phase usually takes place in the first 1/3 of it. Let's say it is true for liquids with b.p. >= 60 degrees C. So, it definitely more efficient than I usually need.

Quote: Originally posted by artemov  

I have the option of topping up $5 in my distillation kit purchase to change a 200mm liebig to a 200mm dimroth (shown above).


As I said I use both. For 29/32 socket I have Dimroth and for 14/23 Liebig. I use Liebig for semi-micro scale operations because it doesn't collect any liquid inside (and for semiscale I use 14/23 system). I am thinking about buying 19/26 Liebig especially for fractional distillations.

So, I think the answer is dependent on the scale of operations. Liebig definitely will not collect any liquid inside. And that huge surface of Dimroth, especially the spiral, can collect it reducing your yield.


[Edited on 19-8-2019 by teodor]