Sciencemadness Discussion Board - Recommendations for decent rotovap

Recommendations for decent rotovap

organicchemist25 - 21-11-2015 at 15:18

Looking to add a rotovap to the laboratory. I see some on eBay, but mostly China-made stuff. I do see some Buchi ones, as well. I was just trying to get some feedback, hopefully before my purchase. I'm not looking to spend more than 2000.00$, if at all possible.

So, if anyone has some suggestions on decent quality for around 2k, I would appreciate it. I don't see the need for more than a 1 or 2 liter for my purposes.

Thanks

organicchemist25 - 21-11-2015 at 15:48

I think they would all be capable of reduced pressure distilling? I would think so, but please update me, if I am incorrect. Also, if I really need to spend a little more to get a good model that will last and have everything I would need, than I will. I really don't want to go over 3250.00$ budget for just personal home use.

Thanks again.

Quatro - 21-11-2015 at 20:35

I think that rotovap is just another word for reduced pressure distillation...

I've also looked on eBay trying to see what was available but I don't know how easy it is to get good rotovaps without spending a huge amount of money... But then again maybe Chinese stuff works just as well?

Maybe look at Hydrion-Scientific on eBay

Dr.Bob - 22-11-2015 at 18:51

I have a number of rotovap parts, all needed to build a rotovap, other then a working motor right now. So if you want to buy the main rototor motor, the rest of the parts I can sell for a very reasonable price. I keep thinking I will buy a motor myself and build a full system, but I have not had time yet. I had two working rotator motors a while back and build and sold two full systems, one on here and one locally, so I can help find the parts needed. I have condensers, water baths, seals, etc. Send me a u2u if interested.

Examples of the missing piece:
http://www.ebay.com/itm/Buchi-Rotovapor-RE111-Motor-Rotary-E...

http://www.ebay.com/itm/Working-Buchi-R-110-Motor-Stand-and-...

http://www.ebay.com/itm/Brinkmann-Buchi-RE-121-Rotavapor-Lab...

Texium - 22-11-2015 at 19:02

I found an old cardboard box in the corner of one of the prep rooms at my school containing a nice rotovap that's just been gathering dust for 20 years.
Quite a shame.

HeYBrO - 22-11-2015 at 22:45

Quote: Originally posted by zts16

I found an old cardboard box in the corner of one of the prep rooms at my school containing a nice rotovap that's just been gathering dust for 20 years.
Quite a shame.

Ask them if you can have it!

JJay - 23-11-2015 at 00:16

Quote: Originally posted by Quatro

I think that rotovap is just another word for reduced pressure distillation...

I've also looked on eBay trying to see what was available but I don't know how easy it is to get good rotovaps without spending a huge amount of money... But then again maybe Chinese stuff works just as well?

Maybe look at Hydrion-Scientific on eBay

It's not just reduced pressure... it's expanded surface area, not to mention heating.

I'd definitely be interested in a cheap rotovap.

Dr.Bob - 23-11-2015 at 17:23

The keys parts of any rotary evaporator are the rotating sealing system (motor, seals, glass stem, etc), the condenser, some water bath or similar heating system (they used steam baths when I started doing chemistry..., I think they were coal fired...:-), and a controllable vacuum source. Many come with a fancy stand, but older ones were just put on a ring stand or lattice work, often multiple pieces connected by vacuum hose in the old days.

If the rotary sealing system works, that is the hardest part, but a good condenser is also key. The heating is just needed as you must provide heat as fast to boil the solvent as fast as the condenser cools or the solvent won't boil quickly. That load depends on the heat capacity of the solvent- hexane is easy, ethyl acetate takes more heat and evaporating ethanol or water requires a huge input of heat. And the vacuum can be an aspirator, cheap diaphragm pump, a fancy multi stage diaphragm pump, or even a real high vacuum pump in some cases (if you want to evaporate DMF or octanol, you will need a great pump).

I have known people to find great deals on them occasionally, as cheap as $500 for some cheap system that needed repairs, up to $4000 for a nearly new Buchi system, and that does NOT include the vacuum system, which is almost always sold separately. Those can run from a $5 aspirator to a $6,000+ vacuum pump, some now are even computer controlled (not that they work very well IMHO).

CharlieA - 23-11-2015 at 19:05

Years ago, I left a solution of a sugar phosphate ester on a rotary evaporator overnight. After all, what could go wrong, right? Well the next morning after discovering the water bath contained a dark syrup with the RB flask originally containing my product floating in it, I realized what could go wrong: first, a power failure caused the vacuum pump and water bath heater to go off, the loss of vacuum led to the flask of solution falling into the water bath, then the power came back on and the water bath turned my product into syrup. Since I was pretty new on the job, I was sure I would be fired. When my German boss (not an ethnic slur) came in, I confessed what happened. After sucking on his pipe a bit (I told you it was years ago), he said "Vell, vat will you do next time?" After I said I would not let a rotary evaporation run over night, he said "Vell, get back to vork!" After 50 or 60 years of work, I can honestly say that I never had a more understanding boss!

@zts16: If the school will give you that rotovap, take it. Operated properly, it is a gentle way to concentrate a solution, or even evaporate it to dryness. I picture a rotary evaporator as a stationary lyophilizer.

organicchemist25 - 30-3-2016 at 17:49

Finally found me a nice Rotovap practically brand new

laserlisa - 1-5-2016 at 11:03

Looks nice.

Which brand and model is it?
How much did you pay?
Does it work well?
Would you recommend it?

Thanks in advance.

prettypolymer - 1-5-2016 at 12:09

Is anybody interested in any of these beauties?

650 EUR for the rotavaps without pump, 850 for the one with pump and manual controller (basically a precision swagelok bleed valve).

items located in germany. shipping will be a bit pricey due to weight and volume.

[Edited on 2-5-2016 by prettypolymer]

[Edited on 2-5-2016 by prettypolymer]

[Edited on 2-5-2016 by prettypolymer]

gdflp - 1-5-2016 at 13:10

Quote: Originally posted by prettypolymer

Is anybody interested in any of these beauties?

The price might factor into that.

prettypolymer - 1-5-2016 at 23:32

thank you, i have edited my post accordingly.