Using a vacuum source with your rotary evaporator comes with a significant set of advantages, like making your processes safer, more efficient, cleaner, and overall, easier. In this blog post, we’re going through all the reasons why owning a rotary evaporator is typically paired with using a vacuum source (either built-in or a vacuum pump).
Depending on the rotary evaporator you’re using, you might already have a built-in vacuum controller and you’ll only need to add a vacuum pump. However, if this isn’t the case, you’ll need to invest in both a pump and a manual (or digital) controller. Controllers don’t come cheap, but there are a few ways to decrease your cost (That we’ll discuss in a future blog post – stay tuned!).
Controllable vacuum sources allow you to adjust the pressure with surgical precision, providing you with the desired evaporation rate. An increase in evaporation rate can therefore be achieved without having to upscale your bath’s temperature, which will allow you to achieve evaporation rates previously unattainable using a bath alone. Using a vacuum source also leads to improved solvent-product separation thanks to the controlled and even evaporation rate. It also decreases the risk of bumping (the formation of bubbles due to hasty boiling of samples; This can lead to your sample splashing out of the flask.).
In regard to safety, using a vacuum source mitigates many risks. The decrease in boiling point of certain temperature-sensitive compounds reduces the odds of them reacting in your mixture. By reducing the pressure inside of the flask, and in tandem with it, the boiling point of your solvents, you can remove high boiling solvents in a quicker (we’re talking a few minutes, or even seconds) and safer manner. Inherently, you can work at lower bath temperatures, and use water instead of oil in heating baths. This is a safer option since using oil can leave behind residues in your evaporation flask which constitutes a fire hazard in the presence of flammable gas vapors.
To sum it up, vacuum makes your processes safer, cheaper, and even easier (specially in cleaning – ever tried cleaning up oil off of your machine?).