Sciencemadness Discussion Board

Using an erlenmeyer flask for refluxing

methyleneblue - 29-3-2017 at 02:05

Hi all,

I'm going to be doing a Fischer-Speier Esterification tomorrow, probably some Isopropyl Acetate. My only issue is, and partially due to laziness, is that I don't have a mantle yet, and can't be bothered setting up an oil bath on the hot plate for a round-bottom flask.

Is it possible to just stick an erlenmeyer underneath a condenser, sit it straight on the hot plate and reflux that way? Or does that do some witchcraft to the reaction and stuff it up? :cool:

PS: Yes, I am using glass joints. The flask and condenser are connected, not just sitting above one another.

[Edited on 29-3-2017 by methyleneblue]

PirateDocBrown - 29-3-2017 at 02:34

How do you propose keeping the vapor from escaping between the condenser and the flask? Or is it an Erlenmeyer with a glass joint?

methyleneblue - 29-3-2017 at 02:36

Quote: Originally posted by PirateDocBrown  
How do you propose keeping the vapor from escaping between the condenser and the flask? Or is it an Erlenmeyer with a glass joint?


Woops. :P
Yep, 24/40 glass joints all the way.

j_sum1 - 29-3-2017 at 02:53

I don't see any particular issues. The only thing is that the shape of an Erlenmeyer lends itself to greater thermal stresses with uneven heating. And you will get uneven heating. The Erlenmeyer will also tend to reflux in the flask -- which could be a good thing or a bad thing depending.

Bottom line, ok unless you are doing something high temp.

methyleneblue - 29-3-2017 at 02:57

Quote: Originally posted by j_sum1  
I don't see any particular issues. The only thing is that the shape of an Erlenmeyer lends itself to greater thermal stresses with uneven heating. And you will get uneven heating. The Erlenmeyer will also tend to reflux in the flask -- which could be a good thing or a bad thing depending.

Bottom line, ok unless you are doing something high temp.


Alright sounds good, Isopropyl Acetate boils at 89°C anyway so I should be fine.
Thanks.

j_sum1 - 29-3-2017 at 03:13

Well at that temp you could easily rig up a water bath. Far less messy than an oil bath IMO and having a ceiling temperature and a bit of thermal ballast makes the process easy to control.

methyleneblue - 29-3-2017 at 03:19

Quote: Originally posted by j_sum1  
Well at that temp you could easily rig up a water bath. Far less messy than an oil bath IMO and having a ceiling temperature and a bit of thermal ballast makes the process easy to control.


Ooo I like that idea.
Will also look into this. Thankyou! :)

XeonTheMGPony - 29-3-2017 at 04:05

I've used brine solutions for this sort of work too, helps suppress waters boiling point making it higher. Some thing for ya to look into.

methyleneblue - 29-3-2017 at 22:32

Quote: Originally posted by XeonTheMGPony  
I've used brine solutions for this sort of work too, helps suppress waters boiling point making it higher. Some thing for ya to look into.


Are you talking about in the actual beaker? Because if so, wouldn't this react with the Alcohol, Carboxylic acid and Catalytic acid and do some crazy reactions?

Tsjerk - 29-3-2017 at 22:42

He is talking about the water bath, it will be a bit safer towards boiling to dryness with the electrical heating set to the same output of heat . You can also put more energy into the reaction, but I don't know if that is necessary. Especially if you use IPA in excess.

[Edited on 30-3-2017 by Tsjerk]

PirateDocBrown - 30-3-2017 at 01:16

Erlenmeyer, condenser, and hot plate are pretty much exactly how I do such things. Water bath, if the temp is low enough. Sometimes a flatbottom round flask. But yeah, all 24/40.

XeonTheMGPony - 30-3-2017 at 08:47

Quote: Originally posted by Tsjerk  
He is talking about the water bath, it will be a bit safer towards boiling to dryness with the electrical heating set to the same output of heat . You can also put more energy into the reaction, but I don't know if that is necessary. Especially if you use IPA in excess.

[Edited on 30-3-2017 by Tsjerk]


You nailed it.