Dr. Beaker - 23-8-2007 at 12:48
This seems basic - but yet tricky.
I needed to make dry 2-butanol (for titration of MeLi).
I asked someone who had done it, and he told me he think he refluxed it with di phosphorous pentoxide.
I added P4O10 to my butanol, and it just kept disolving with tremendous amount of heat released.
I'm prety positive this is not just reaction with the water in my butanol, since I put huge amounts of the oxide and it just kept disolving very
rapidly.
I have 2 speculation of what happened:
1. simple solvation of the oxide
2. formation of phosphoric esters (after all the oxide is the anhydride of H3PO4)
what do you think?
[Edited on 23-8-2007 by Dr. Beaker]
Klute - 23-8-2007 at 17:39
I would think you made some phosphoric esters (and possible some alkenes from deshydratation); only tertiary alcohols don't react that way IIRC (but
they will surely deshydrate).
Using molecular seives to dry the butan-2-ol could be enough, or using a little amount of sodium + a butan-2-ol ester (wich you just made 
) as with ethanol would give a very dry product if that method is equally appliable
to secondary alcohols (I can't see a reason why not). Reflux and distillation other magnesium or CaO could be equally satisfying.
Well, here what is mentionned in "Purification Of Laboratory Chemicals" 4th edition:
-sec-Butyl Alcohol [15892-23-6] M 74.1 ;b 99.4°; d 0.808 Purification methods are them same as for n-Butanol. These include drying
with K2CO3 or CaSO4, followed by filtration and fractionnal distn. refluxing with CaO, distn., then refluxing with magnesium and redistn.; and
refluxing with, then distn. from CaH2. Calcium carbide has also been used as drying agent. Anhydrous alcohol is obtained by refluxing
sec-butylphtalate or succinate. (For method see Ethanol). Small amounts of alcohol can be purified by conversion to alkyl hydrogen phtalate and
recrystn [Hargreaves, JCS 3679 1956]. For purification of optical isomers see Timmermans and Martin [JCP 25 411 1928]
I really advise you to download this book (it's available in the ref forum) it's really handy.
[Edited on 24-8-2007 by Klute]
Sauron - 23-8-2007 at 20:09
With water, phosphoric acid
With alcohol, phosphate ester(s) of that alcohol.
Most likely a mix of monoester and diester. Triesters are more difficult. Making phosphate triesters is an art.
So it is not a good drying agent for such.
But a very good drying agent for anything it is inert to, like hydrocarbons, halocarbons and ethers.
Just a pain in the ass to handle (floculent.)
[Edited on 30-9-2007 by Sauron]
Dr. Beaker - 24-8-2007 at 09:50
Thanx for the answers.
However, the refs forum has password - how do I get it?
Sauron - 24-8-2007 at 19:18
I believe I already have that book, if so I will find the pdf, and load it onto my 4shared.com folder abd post the url here. You will have to scroll
down the list to get past all the Aldrichemica Acta files, as the list is alphabetical.
It's in thw books subfolder
http://www.4shared.com/dir/2245331/5a78115f/sharing.html
The only way to get PW for References is to request it from a moderator.
I suggest vulture or Polverone as they are nice people.
[Edited on 25-8-2007 by Sauron]
Dr. Beaker - 25-8-2007 at 00:16
Thanks again.
Real nice to have this book as a pdf.
cheers.
Sauron - 25-8-2007 at 00:23
Don't mention it. Just tell everyone what a nice guy I am.
Protactinium - 29-9-2007 at 14:09
If the butanol had any water in it and the P4O10 was of good quality, it would've more than likely caught fire. It only takes a drop of water to cause
enough heat to ignite nitrocellulose (guncotton). That's if the the P4O10 is recently new, it's some pretty nasty stuff and one of the the best
dehydrators.
Sauron - 29-9-2007 at 14:43
Suffice it to say that P4O10 is an incompatible dessicant for alcohols, amines, phenols etc. Also ammonia gas and vapor phase amines. Thiols too.
Pretty much anything that can form an ester, thioester or amide.
Dr. Beaker - 30-9-2007 at 13:08
And also (as I recently learned) trimethyl silyl ethers.
It is , however, very efective in making ultra dry nitriles and halo-hydrocarbon (which would have reacted with NaK).
[Edited on 30-9-2007 by Dr. Beaker]