Building a bigger and better solvent still | Chemical & Engineering News
Volume 95 Issue 13 | p. 8 | Concentrates
Issue Date: March 27, 2017

Building a bigger and better solvent still

Chemists aim to prevent waste and save money with a versatile, safety-conscious midscale automated lab system
Department: Science & Technology
Keywords: green chemistry, distillation, solvent
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These homemade distillation stills offer the benefits of saving money and preventing lab waste.
Credit: Stefan Böhmdorfer
A photo shows a pair of distillation columns in a lab fume hood.
 
These homemade distillation stills offer the benefits of saving money and preventing lab waste.
Credit: Stefan Böhmdorfer
[+]Enlarge
Graduate student Slavica Hell (left) poses with Böhmdorfer and one of their new stills; the automated control panel is shown on the wall at right.
Credit: Courtesy of Stefan Böhmdorfer
A photo of Slavica Hell and Böhmdorfer in front of a pair of distillation columns in a lab fume hood.
 
Graduate student Slavica Hell (left) poses with Böhmdorfer and one of their new stills; the automated control panel is shown on the wall at right.
Credit: Courtesy of Stefan Böhmdorfer

Most labs have a small still for quickly purifying solvents. But for Stefan Böhmdorfer and his colleagues at the University of Natural Resources & Life Sciences in Austria, that wasn’t enough. The researchers carry out a lot of chromatography and realized they had much to gain by purifying and reusing their solvents, rather than paying someone to cart them away for recycling. The team had a hard time finding a commercially available still that could do everything they wanted, including handling between 2-L bench-scale and 30-L pilot-scale amounts, having fully solvent-resistant components, and offering precise control over separating solvent fractions. So the researchers decided to build their own system. That’s not a new idea, but the team spared no detail in designing its system to handle solvents of all polarities and a wide range of boiling points and to collect fractions automatically (Org. Process Res. Dev. 2017, DOI: 10.1021/acs.oprd.7b00007). The researchers built two stills for 6-L batches inside a walk-in fume hood. The basic setup includes a 10-L round-bottom flask, a 100-cm-long/30-mm-diameter packed column, a condenser, drying tubes, and collection vessels. Temperature sensors and electronically controlled valves enable the automated fraction collection and also serve as a safety feature to shut the system down if something starts to go wrong. The distilled solvents are typically of higher purity than the analytical-grade solvents the group was buying. “I am convinced that a lot of research groups are facing the same situation of having larger amounts of easily redistillable solvents and can decide to build their own device,” Böhmdorfer says.

 
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Comments
Steve Ritter (April 5, 2017 9:57 AM)
Brilliant redistillation of words, by UPenn chemistry poet Andrew McGhie:

A Still is Still a Still

A still is still a still
Of that there is no doubt
It’s used by chemists at their will
To get impurities out
Now solvents they are said to be
The workhorse of the lab
And must be of highest purity
Irrespective of the tab
One way of doing this, for sure
Is to have them re-distilled
Commercially and they’ll come back pure
But at the cost, one won’t be thrilled
So Stefan Bohndorfer and colleagues
Set out to build their own
And did so quite successfully
With a system that’s ‘home grown’
It has all the bells and whistles
They thought that they would need
And with sensors, it just bristles
A work of art, indeed
So they now can run at will
In batches up to six liters
Obtaining higher purity still
Could anything be neater
One extra benefit they obtained
It is no hallucination
That due to all their work and pain
They got a publication!

Andrew Roxburgh McGhie 04.05.2017

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