## Can condensation in a reflux condenser be calculated?

simple-guest-7125 - 21-11-2018 at 18:36

I did a little poking around looking for an answer to this but wasn't finding the right search terms or something.

This is more of a question about selecting the right equipment so I hope someone can help me understand.

I'm not bery knowledgeable about chemistry as far as terminology. I just understand some of the basic concepts. I'm not even sure if the question I have is very important to know before selecting the best reflux condenser.

What I'm wondering is - If you have say 3 substances that you are going to reflux together call them substance A, substance B, and substance c. How can it be calculated the length and type of column to use for you rxn?

Thanks.

Attachment: Solvent-Free-Formalin-Free-Eschweiler-Clarke-Methylation-for-Aminese.pdf (137kB)

DraconicAcid - 21-11-2018 at 19:14

Basically, it depends on the temperature of your cooling water (and the rate of flow), the boiling point of the solvent(s), and how vigorous the boiling is. I don't see how you would calculate it, but if you see the condensation front near the top of your condensor, run the cold water faster.
DraconicAcid - 21-11-2018 at 20:17

Volume is also a factor- if I was refluxing 50 mL of dichloromethane, a short column would be sufficient. For 1 L, I'd use a much larger one.
macckone - 22-11-2018 at 07:10

You can calculate condensation but the visual method is usually more reliable. For a commercial operation, the engineer would calculate it. You need to know the heat of evaporation, the thermal conductivity of the condenser, the thickness of the condenser and the surface area of the condenser. The two remaining factors are flow rate and temperature of the cooling fluid. You plug all of that into formulas and you get the maximum amount of substance condensed.
DavidJR - 22-11-2018 at 07:50

Lots of useful info here: http://www.separationprocesses.com/Distillation/MainSet1.htm
simple-guest-7125 - 24-11-2018 at 09:15

Thank you all for so much useful tips and information. Thanks for the link DavidJR. This really helps me understand.

Sulaiman - 25-11-2018 at 08:00

On the assumption that your question is equivalent to;

which reflux condenser should I buy ?

I can recommend this cheap but efficient reflux condenser
https://www.ebay.co.uk/itm/200mm-24-29-Glass-Coiled-Reflux-C...
(there are similar available for different neck sizes)

Tsjerk - 25-11-2018 at 12:07

The condenser Sulaiman recommends should be able to condense anything as long as your cooling water is cold enough.
DavidJR - 25-11-2018 at 12:27

Yes, I have one of those too and it works pretty well.

You don't want a graham condenser (where the vapour path itself is coiled), you want a coil condenser (where the vapour goes around a coiled tube of coolant). To make things more confusing the Chinese sellers seem to use the terms interchangeably.