Sciencemadness Discussion Board - How to dry various solvents

How to dry various solvents

Melgar - 18-2-2011 at 23:35

I found this page that gives a nice list of drying agents that work with different solvents:

http://delloyd.50megs.com/moreinfo/drying.html

I learned a lot of neat stuff; for example that ethanol can be dried with CaO or MgO, or ether can be dried with CaCl2.

Another interesting page on that site lists which common solvents are miscible with each other:

http://delloyd.50megs.com/moreinfo/immiscible.html

Lots of good information there.

vulture - 19-2-2011 at 03:57

It really depends on what your definition of "dry" is. Ether dried over CaCl2 will still contain a detectable amount of water which can interfere with certain reactions (organometallics, polymerizations).

So use with caution.

White Yeti - 4-8-2011 at 07:24

Anhydrous calcium sulphate is the best drying agent for most purposes.

rstar - 29-9-2011 at 04:11

Phosphorus pentoxide or P2O5 (molecular P4O10) is one of the most powerful drying agents. It can dry dilute H2SO4 to make it concentrated, but if left for more time it can also dry conc. H2SO4 to its anhydride SO3.

ScienceSquirrel - 29-9-2011 at 04:32

It also rips the shit out of most things organic turning into a yucky black gel of phosphoric acid in the process

Chemistry Alchemist - 29-9-2011 at 05:03

I also wanted to know how i could dry methanol and i came across this site which has a list of solvents and then the chemicals needed for drying...

http://delloyd.50megs.com/moreinfo/drying.html

blogfast25 - 29-9-2011 at 05:21

I'd never heard of this delloyd site before, looks quite interesting going by homepage and a few samples. Is it well known in the USA? Trustworthy?

rstar - 29-9-2011 at 05:21

Some volatile solvents can also be dried by passing hot air through them

HexJam - 3-10-2011 at 07:11

My favourite drying agent is good ol' CuSO4, it works well and is compatible with a lot of solvents and changes colour when wet - bonus!

Endimion17 - 3-10-2011 at 11:50

Quote: Originally posted by HexJam

My favourite drying agent is good ol' CuSO4, it works well and is compatible with a lot of solvents and changes colour when wet - bonus!

Yeah, but it isn't something you'll use in industrial processes that deal with food grade chemicals. That's why ethanol is dried using calcium oxide. Traces of calcium pose no problems, unlike copper traces.

I'm not sure of the data on that page is that accurate. I see they've put ether and water as immiscible, but that's not true. Ether dissolves in water, though very little. The solution can be used for weak, primary sedation of certain lab animals that breathe by gas diffusion over the skin.

Lambda-Eyde - 3-10-2011 at 11:54

Quote: Originally posted by Endimion17

I'm not sure of the data on that page is that accurate. I see they've put ether and water as immiscible, but that's not true. Ether dissolves in water, though very little.

If two solvents are miscible, it means that they can be mixed in all proportions - which is not true for water and diethyl ether.

peach - 3-10-2011 at 12:05

I'd love a sodium still, but Chemglass are pretty pricey and their sole UK distributor charges more for the privilidge; and I mean more than the VAT, duty and shipping.

I have the sodium, benzophenone, vacuum, inert gas, special syringes and desire, but cash is always the enemy.

The delloyd site is great yeah! He's got some other useful tables up on there. And it's funny you should mention it at this moment, because just yesterday I thought I'd do some more printing and laminating.

I like having physical copies of useful tables so, if I forget something or am not sure, I can whip them out and check it right on the spot.

I've also pulled all of the most common solvents out of the Sigma physical properties database and made a table of their boiling points across the pressure range, so I can quickly estimate what's going to do what when I do X.

The only current annoyance is them all being in different formats. I have thought about recompiling it all into a simple text document so people can grab it all in one go, click print, and have a mini-guide to reference. That's competing with me writing up the numerous experiments I've done recently, but I will attempt to get it done and drop the finished lot up on here.

Lamination is useful, as they'll be hammered by all the weird stuff they get exposed to if not.

{edit}In that pile, there is:
The drying table from delloyd and erowid
The wiki table of densities, BP's and polarities
The flash point of about hundred volatiles
And there's another nomograph on the back of one of them

Azeotropes would also be useful, and IARC's carcinogen reference, and autoignition temperatures.

[Edited on 3-10-2011 by peach]

hkparker - 3-10-2011 at 13:20

If you want to throw those files up on the FTP I know I would appreciate it peach! I too should make some pages with those useful charts on them.

Endimion17 - 3-10-2011 at 13:51

Quote: Originally posted by Lambda-Eyde

Quote: Originally posted by Endimion17

I'm not sure of the data on that page is that accurate. I see they've put ether and water as immiscible, but that's not true. Ether dissolves in water, though very little.

If two solvents are miscible, it means that they can be mixed in all proportions - which is not true for water and diethyl ether.

Oh. Well ok, it's English language. My bad.

peach - 5-10-2011 at 03:59

Quote: Originally posted by hkparker

If you want to throw those files up on the FTP I know I would appreciate it peach! I too should make some pages with those useful charts on them.

Okay.

I've started copying them all into a single text document, which has thus far taken at least 12 solid hours of staring at the screen, reformatting tables and so many entries my brain is going numb.

But it should be reasonably well done within the next few days, whereupon I'll list it up for people to have a look at / complain about so I can correct any errors or reformat things.

I'll start a new thread related specifically to the document, so people have a specific point to come back to if / when they find any errors or to make suggestions for changes.

I will be STUNNED if there isn't a mistake in one or two of the values, but it's as close as I can get it on the first attempt.

[Edited on 5-10-2011 by peach]

hkparker - 5-10-2011 at 10:55

Don't work too hard!

But thank you, I really appreciate it

unionised - 5-10-2011 at 11:36

There's at least one error in the miscibility tables cited in the OP. Has anyone else spotted it?

Nicodem - 5-10-2011 at 12:23

Other than listing DMF as immiscible with water, I think all the other combinations are correct.

Though it should be kept in mind that "immiscible" here only means that two solvents do not mix in all the composition range, but they can be quite miscible in borderline ranges. For example, methanol does dissolve substantially in heptane and heptane dissolves substantially in methanol, but they do not mix in all the possible ratios. Analogously, methyl acetate and water do not mix in all ratios, but they do so freely at the borderline ranges.

Panache - 6-10-2011 at 03:33

I surprised you dorks haven't whipped some code for your iPads to allow for voice prompted data sets to be accessed and read back out to you while your seventeen reactions are running and you are assigning H1 peaks on yesterday's workups. So inefficient.
Remember that bit in Good Will Hunting where he glances over her NMR homework and jots out the structure in four seconds. I wonder if anyone can actually do something like that, I don't think so.
Anyway while you guys are down at Kinko's laminating you might have a look at Wolfram.com. I find it the place I go to when the CRC fails, which isn't very often really. If you're going too invest in a CRC I suggest buying one from the seventies they are best IMHO. They are idiosyncratic however and require one to become accustomed to them, this can take time.

unionised - 6-10-2011 at 10:15

"I surprised you dorks haven't whipped some code for your iPads to allow for voice prompted data sets to be accessed and read back out to you while your seventeen reactions are running and you are assigning H1 peaks on yesterday's workups. So inefficient."
Personally, I just remember the data.

smaerd - 18-12-2012 at 15:39

I recently found an article showing the efficacy of using 3 angstrom molecular sieves, columns of sillica, as well as columns of alumina on drying a variety of solvents. I found these to be incredibly valuable and figured it would be kind to openly share this information.

Using sodium stills, and distilling from benzophenone isn't really an option for the most of us.

In the first article it mentions using schlenk techniques in a glove-box for the columns of activated alumnia and silica. I was wondering what kind of work around would work for us?

What I was thinking was running a chromatography column with a drying-tube on-top into a either a two neck flask with an additional drying tube or just a one neck flask. Obviously having effectively dried the glass-ware prior to working. Would building a dedicated "Dry box", be over-kill? A cheap hygrometer could help keep things in perspective, granted it won't read down to the low values wanted, but it could be pumped with air sent through tubes with drying agent in them, or just be lined with dessicant.

The second article is more about aprotic solvents and is a bit older but it holds some relevant information.

Attachment: phpWphOCb (769kB)
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Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several desiccants
D. Bradley G. Williams and Michelle Lawton
The Journal of Organic Chemistry 2010 75 (24), 8351-8354
DOI: 10.1021/jo101589h

Attachment: Desiccant efficiency in solvent drying dipolar aprotic solvents.pdf (420kB)
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Desiccant efficiency in solvent drying dipolar aprotic solvents
David R. Burfield and Roger H. Smithers
The Journal of Organic Chemistry 1978 43 (20), 3966-3968
DOI: 10.1021/jo00414a038

[Edited on 18-12-2012 by smaerd]