BaFuxa
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Dean Stark Apparatus : Worth it?
Hi all,
I am considering buying a Dean Stark apparatus. It is quite an interesting design and it is a very very sexy piece of glassware. However upon due
consideration I am now wondering whether this is really an intelligent purchase, here is why I am hesitant :
- The dean stark is used to get rid of aqueous azeotropes, since I think I can achieve the same result with dirt cheap drying agents ( CaCl2,
anhydrous Mg/CuSO4 etc) in virtually no time what is the point of getting one ?
-a dean stark will require additional solvents, like toluene which is not easy to get at all. It seems to generate more spendings than savings.
Distillation is also always extremely slow.
Am I missing something that would make a Dean Stark an essential part of my lab ? Do you have one ?
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j_sum1
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Mine has never been used but that is more a reflection of the long period of time that my lab has been in boxes than anything else. It was remarkably
cheap and worth it just as a cool-looking bit of glass.
Here are some things that a DS can do:
separate azeotropic mixtures (typically toluene/water)
separate a biphasic reaction product
separate out the products of steam distillation
produce anhydrous oxalic acid and other anhydrous substances by exploiting a water azeotrope
And this is without the use of any consumables such as molecular sieves, CaCl2 or other drying agents. It is also the kind of glassware that might
find other applications to a creative chemist.
Note that the standard DS will collect the heavier fraction and return the lighter fraction. There are similar devices that will do the reverse --
depending on what you need. I have also seen (pictures of) a crazy bit of glass that could be configured to do both.
https://www.sciencemadness.org/whisper/viewthread.php?tid=31...
and the following posts:
https://www.sciencemadness.org/whisper/viewthread.php?tid=31...
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SWIM
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Worth it.
In addition to the above they're good for driving all sorts of reactions by removing water. Doing that with drying agents in the reaction can be
problematic. (But I have heard of some reactions like this being done with drying agents in a Soxhlet)
They can be used as a slightly lame version of a solvent distillation head as well.
A short path head is nice, so is a Soxhlet, but a dean Stark is useful in more different ways, so unless you do a lot of extractions from solids, or a
lot of delicate distillations of viscous oils you're probably best off with a DS trap.
Make sure its got a valve on the base of the collection tube.
That's a Clevenger trap. Some folks call it a Dean Stark trap, but I still call it a Clevenger trap.
Well Okay then. I'm gonna go get me some french fried potaters Um-Hmmm.
EDIT: Did catch-22 function as a Clevinger trap?
[Edited on 2-11-2017 by SWIM]
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Dr.Bob
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I have lots of them used in virtually every glass joint size imaginable. (14/20, 24/40, 29/42, etc), and sell them for $15-30, depending on the size
and complexity. You don't really need a big volume on the collection side, most reactions only generate a few ml of water, since it has a low MW.
So if you go to a 14/20 joint, the cost and amount of extra solvent needed (10-20 ml) is quite small.
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NEMO-Chemistry
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I dont have one, but wished I did. As mentioned they are usable even when not needed, and just look so cool 
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aga
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I bought two Dean-Stark traps in total (ebay and alcohol are a dangerous mix)
The first was a graduated thing with no stop-cock, which has never been used, ever.
The second one (with a stop-cock) arrived broken, so i ended up melting the glass to seal the side-arm to get a glass pipe with a valve on the bottom
plus a 24/40 ground glass joint on top.
This gets used for most distillations as it provides a handy way to cut fractions without any rush or fuss.
A sep funnel would serve pretty much the same, yet the re-purposed item gets used solely for that.
Edit:
The Chinese supplier was unhappy that it arrived broken, yet it was entirely their fault due to silly packaging (everyone on SM who got one got a
broken one).
Rather than screw them over completely by claiming 100% of the money back, i agreed to a half-refund, seeing as i could see a use for the broken
pieces.
Depends on what you assign value to i guess.
[Edited on 2-11-2017 by aga]
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