Sciencemadness Discussion Board

in vacuo in older texts.

organicchemist25 - 1-11-2017 at 12:55

Im not sure if this is a beginnings question or organic topic. Sorry if its posted in the wrong area.

Ive been wanting to know exactly what in vacuo means. I see it in a lot of literature. Nothing really in text books explain it and google is kind of unclear.

I used to have the same issue with in situ, but I know that now.

So, when literature says "removed by in vacuo", or "solvent is stripped" does that mean distilled off from out of the boiling flask or use my rotavap? or either one?

Do I use my hot plate and just evaporate it? I would think I would like to recover my solvent, right? And, I would know to use my vacuum if reduced temp/pressure was needed. How would I know when to stop evaporating? total dryness? I wouldn't want to scorch what I am trying to isolate.

I also have a dessicator with a vacuum take off that needs to be sealed with grease when vacuum is turned on. When would this be useful? If you have a product that you want to remove any solvent from fast or more throughly?



[Edited on 1-11-2017 by organicchemist25]

unionised - 1-11-2017 at 13:31

"So, when literature says "removed by in vacuo", or "solvent is stripped" does that mean distilled off from out of the boiling flask or use my rotavap? or either one? "
All it means is "in a vacuum"- realistically it means under low pressure.
So it could be vacuum distillation a rotovap (as long as it's no so old they weren't invented).

stripping

Sulaiman - 1-11-2017 at 13:45

https://upload.wikimedia.org/wikipedia/commons/e/e9/Tray_Dis...

JJay - 1-11-2017 at 13:51

That means "in a vacuum" in Latin, but if you want to look like a major science snob, you can put an umlaut or flat bar over the o.

organicchemist25 - 1-11-2017 at 14:46

Quote: Originally posted by unionised  
"So, when literature says "removed by in vacuo", or "solvent is stripped" does that mean distilled off from out of the boiling flask or use my rotavap? or either one? "
All it means is "in a vacuum"- realistically it means under low pressure.
So it could be vacuum distillation a rotovap (as long as it's no so old they weren't invented).


Thanks! seems like I got what i was looking for. Ill just use the rotavap as first option and then vacuum distillation as second option if I need to go that route.

thank you for clearing it up.

organicchemist25 - 1-11-2017 at 14:50

Quote: Originally posted by JJay  
That means "in a vacuum" in Latin, but if you want to look like a major science snob, you can put an umlaut or flat bar over the o.


:D It doesn't matter if I sound like a snob or not :) I just want to understand some of the jargon in older literature. They definitely didnt talk like that in my classes or labs, but I didn't ask way back then .

organicchemist25 - 1-11-2017 at 14:54

Quote: Originally posted by Sulaiman  
https://upload.wikimedia.org/wikipedia/commons/e/e9/Tray_Dis...


I still don't really understand that diagram much. I remember learning a little about plates/theoretical plates in the reflux or fractionating column.

Is that part of when they mention "solvent is stripped"?

Thank you for your replies. You have been helping me with a few of my posts. I definitely appreciate it.

Sulaiman - 1-11-2017 at 15:08

It is my understanding that the lower b.p. parts of the feedstock will rise in the 'rectification' section
and the higher b.p. fractions will descend through the 'stripping' part of the column.
Like most, I do batch distillations with my feedstock in the pot,
so I only use rectification (rectified spirits etc.) and no stripping.

I believe that solvents usually have a lower b.p. than the products that they extract,
so 'stripping' seems an inappropriate use of the term for solvent recovery.


[Edited on 1-11-2017 by Sulaiman]

The Volatile Chemist - 1-11-2017 at 15:28

Quote: Originally posted by Sulaiman  
It is my understanding that the lower b.p. parts of the feedstock will rise in the 'rectification' section
and the higher b.p. fractions will descend through the 'stripping' part of the column.
Like most, I do batch distillations with my feedstock in the pot,
so I only use rectification (rectified spirits etc.) and no stripping.


[Edited on 1-11-2017 by Sulaiman]

This is true - however it has little to do with the main topic of 'in vaccuo'. When I hear the phrase (which I probably just butchered the spelling on) I tend to initially just think of the typical rotovap procedure.