Sciencemadness Discussion Board

How to make a ammonia in anhydrous ethanol solution?

Itsjustme - 4-5-2011 at 10:00

How would one make a, lets say, 25% ammonia in anhydrous ethanol solution?

Bubbeling ammonium gas into anhydrous ethanol is not an option.

So im guessing an ammonia salt.

But which one would be best?

Best regards

bahamuth - 4-5-2011 at 10:09

25% ammonia in anhydrous ethanol implies that ammonia gas (anhydrous also) is bubbled into anhydrous ethanol, no other way as I see it. No salt would do, since the ammonia salts that come to mind would split off water on liberation of the ammonia.

Why not the "bubbling" route?

Itsjustme - 4-5-2011 at 10:27

ammonium gas is dangerous to work with...
plus its not something that is just arround...
but if no other options are possible...
could it be possible to create it from concentrated ammonia?

Itsjustme - 4-5-2011 at 10:30

maybe adding concentrated ammonia to the anhydrous ethanol and then drying it with MgSO4?

bahamuth - 4-5-2011 at 10:48

Think 25% ammonia in ethanol will be quite as dangerous as gaseous ammonia, since 25% probably is way over the solubility of ammonia in ethanol, and the solution needs to be kept at the negative side of the scale to prevent boiling of the ammonia/ethanol.

I know how dangerous ammonia gas can be, have a lot of scar tissue in one of my nostrils, almost closed, from ammonia gas about 5 years ago, had nosebleed for a year after the exposure.
Anyways, I would totally test the gas route, easy, clean, cheap and would increase your knowledge and technique in chemistry.

Sedit - 4-5-2011 at 10:58

Alkoxide and Ammonium salt is said to work.

Methyl.Magic - 4-5-2011 at 11:06

You can dissolve metallic sodium to make EtONa, then add Ammonium chloride (or much better ammonium acetate !!) and filter the NaCl cake and wash with anhydrous EtOH. I already used that it works for 5% solution but I think for 25% there is too much NaCl and it's a waste of Na and time because the reaction must be performed for 2 days because of the poor solubility of ammonium chloride in ethanol.

You cannot dry with MgSO4 because magnesium makes complex with ammonia. Try adding conc. ammonia to ethanol, then dry it over Na2SO4 then CaO but it requires a lot of drying salt and as soon as you washed the salt, you immediatly too much dilute your solution.

Best way is generating NH3 gas IMO. No problem if done correctly : NH4+ NaOH 80% --> NH3 --> pass through CaCl2 or BaO--> empty flask --> ethanol anhydrous --> empty flask --> H2SO4 diluted

Itsjustme - 4-5-2011 at 11:22

Quote: Originally posted by Methyl.Magic  
You can dissolve metallic sodium to make EtONa, then add Ammonium chloride (or much better ammonium acetate !!) and filter the NaCl cake and wash with anhydrous EtOH. I already used that it works for 5% solution but I think for 25% there is too much NaCl and it's a waste of Na and time because the reaction must be performed for 2 days because of the poor solubility of ammonium chloride in ethanol.

You cannot dry with MgSO4 because magnesium makes complex with ammonia. Try adding conc. ammonia to ethanol, then dry it over Na2SO4 then CaO but it requires a lot of drying salt and as soon as you washed the salt, you immediatly too much dilute your solution.

Best way is generating NH3 gas IMO. No problem if done correctly : NH4+ NaOH 80% --> NH3 --> pass through CaCl2 or BaO--> empty flask --> ethanol anhydrous --> empty flask --> H2SO4 diluted


Ok seems like generating gas is the way to go.

How would i make a 15% solution in the ethanol? I mean how could i make sure it is 15%? Use a scale?

How would i pass it thrue the CaCl2? Just pack a tube?

I guess the H2SO4 is to capture excess gas? Or?

Also which salt would be best/safest?

[Edited on 4-5-2011 by Itsjustme]

DJF90 - 4-5-2011 at 11:25

I suggest you get yourself a lab manual and practice with a less hazardous material, at least until you get some vague idea of what you're doing.

Itsjustme - 4-5-2011 at 11:30

Quote: Originally posted by DJF90  
I suggest you get yourself a lab manual and practice with a less hazardous material, at least until you get some vague idea of what you're doing.


Thanks for the warning but i have to learn how to do this.
I work at a lab, but i just finished school and i havent worked much with ammonia.

[Edited on 4-5-2011 by Itsjustme]

Itsjustme - 4-5-2011 at 11:40

Ok i found this:

solubility (ammonia) in absolute ethanol at 0°C : 20% (w/w)
solubility (ammonia) in absolute ethanol at 25°C : 16% (w/w)

http://www.natscience.com/Uwe/Forum.aspx/chem/4620/16-ammoni...

So i guess i just bubble ammonia into ethanol at room temp and i would eventually get a 13%-16% solution approx.


[Edited on 4-5-2011 by Itsjustme]

bahamuth - 4-5-2011 at 12:34

Preweigh the ethanol, and weigh it afterwards.
Keep the ethanol cold, salt/ice bath or colder and just bubble ammonia until it appears not to absorb any more.
If you need accurate conc. you would have to titrate it, backtitration against dilute sulfuric acid with standarized sodium hydroxide solution.

For drying I used a very large test tube, 30mm dia. with a glass tube all the way to the bottom covered with some glasswool, filled it almost up with anhydrous CaCl2 packed it with som more glass wool, added a outlet tube to that end, so I had one tube in the bottom of the test tube, and one in the top, just in the rubber stopper really, corked it with a rubber stopper with two holes accommodating the two tubes. Used a lot of vacuum grease as not to break any glass tubing. Worked like a charm for the synthesis of about 500 gram anhydrous ammonium acetate.

Itsjustme - 4-5-2011 at 12:51

Quote: Originally posted by bahamuth  
Preweigh the ethanol, and weigh it afterwards.
Keep the ethanol cold, salt/ice bath or colder and just bubble ammonia until it appears not to absorb any more.
If you need accurate conc. you would have to titrate it, backtitration against dilute sulfuric acid with standarized sodium hydroxide solution.

For drying I used a very large test tube, 30mm dia. with a glass tube all the way to the bottom covered with some glasswool, filled it almost up with anhydrous CaCl2 packed it with som more glass wool, added a outlet tube to that end, so I had one tube in the bottom of the test tube, and one in the top, just in the rubber stopper really, corked it with a rubber stopper with two holes accommodating the two tubes. Used a lot of vacuum grease as not to break any glass tubing. Worked like a charm for the synthesis of about 500 gram anhydrous ammonium acetate.


Ty very much.
Which salt would be best and safest to create the gas?

bahamuth - 4-5-2011 at 21:40

I would just do as Methyl.Magic. Get cheap commercial household ammonia and then basify it, perhaps heat it a little.
Quote: Originally posted by Methyl.Magic  
Best way is generating NH3 gas IMO. No problem if done correctly : NH4+ NaOH 80% --> NH3 --> pass through CaCl2 or BaO--> empty flask --> ethanol anhydrous --> empty flask --> H2SO4 diluted

Ebao-lu - 5-5-2011 at 00:53

Beter not to use CaCl2. It may can form complexes with NH3
"2, anhydrous calcium chloride: their low cost, and strong drying is widely used. Drying speed, can regenerate, dehydration temperature 473K. Generally used to fill dryers and drying tower, dry drugs and a variety of gases. Can not be used for drying ammonia, alcohol, amine, acid, ketones, aldehydes, esters.)"
http://www.nwregionalstrategy.com/?p=96

smuv - 5-5-2011 at 08:14

It is a lot easier to just use the search engine and see how things are done instead of just speculating about it.

Panache - 5-5-2011 at 22:36

At absolute zero i think it would be 100% miscible, you however need a subatomic 'forklit' to mix everything up. Perhaps search for this in wiki.This thread is borderline hopefully this post pushes it over. If you have never worked with ammonia please try ti small scale firstly like 100ml household ammonia.

jon - 6-5-2011 at 21:45

dry ice acetone bath use a suckback trap and bubble ammonia in by dropping conc. naoh onto ammonium salts.
use a ceramic gas dispersion attachment or your ammonia will simply bubble out.
you can get concentrations as high as 35% in ipa at that temp.
but as it warms watch out.
better have a vessel ready to contain it.
and if your doing what i think your doing ethanol gives shit yeilds (around 20%)
use ipa.
you don't need that concentration 10-12% will do and yeah ammonia will asphixiate you, as in chocking can't breathe.
it's dangerous if you don't know what you are doing.
keep a gallon of vinegar and sand handy in case of spills.

[Edited on 7-5-2011 by jon]

captaindrum - 8-5-2011 at 14:25

You can use NaOH + NH4Cl, boil the solution gently, condense the vapors, pass the gas through a column packed with NaOH to set free of water vapor and bubble it through ethanol.

Even absoulute EtOH has %0.5 water, so you can treat it with anhydrous MgSO4 first.

After a quick google search with quotation marks, I got the feeling that you are following TIHKAL. I must say, you REALLY should avoid what you are planning though. Most of your precursors are dangerous and hard to obtain. More important than all: the "product" is dangerous.

My humble advice, please don't.

Best regards...

jon - 8-5-2011 at 17:22

ummm mgso4 does'nt work for drying ammonia amine solutions already tried it.
and why bother passing ammonia water vapor through a column of NaOH?
i can tell you haven't actually done this, because what happens is NaOH cakes up and the back pressure builds and ammonia escapes and you get gassed.
the way it was done was to pass it through a drying tube containing lime and naoh even this i don't recommend for the same resons.
if you drop naoh onto an ammonium salt as long as the solution is cool it won't carry very much water with it.
if you do it the other way around ie. drip ammonium solution onto solid naoh it will get wildly exothermic and steam off water.
not only that but the ammonium salt will clog you funnel too.
just do it that way.


[Edited on 9-5-2011 by jon]

captaindrum - 9-5-2011 at 10:36

Quote: Originally posted by jon  
ummm mgso4 does'nt work for drying ammonia amine solutions already tried it.

Sorry if I told it wrong, but I suggested MgSO4 to dry the pure alcohol, not the ammonia solution. Ammonia reacts with MgSO4.
Quote: Originally posted by jon  

and why bother passing ammonia water vapor through a column of NaOH?

.......NaOH cakes up......

To dry the gas completely. Not packed tight of course.


BTW, I have some special glassware that I designed. Some of them turned out more useful than originally intended, one of them is a precious column designed for THIS.. I love being able to get these made, custom borosilicate column with two ground joints cost less than $20 :D

smuv - 9-5-2011 at 11:15

don't use MgSO4, dont use CaCl2.

http://www.sciencemadness.org/talk/viewthread.php?tid=16061

I dont even know why I post my procedures.

Arthur Dent - 9-5-2011 at 11:30

Quote: Originally posted by captaindrum  
Not packed tight of course.


I always wondered about that... I have a vacuum dessicator and when I fill the bottom with CaCl2 prills, upon exposure to moisture, the prills increase in size quite a bit, so I always thought that there must be a magic technique to pack a glass column with calcium chloride or sodium hydroxide and not see it shatter under the pressure of the expanding salts?

Would plain pink glass wool do the trick?

Robert

Methyl.Magic - 11-5-2011 at 23:20

You can use NaOH or anhydrous K2CO3 instead.

Panache - 12-5-2011 at 05:20

What with all the codified crap, what are you making, there really i very little chance that mentioning it now will be the tipping point for some sort of action against you.
Drying NH3, cold water condenser at the top of which you have a tap to create backpresure within the condenser, slowing the passage of the ammonia and hopefully drying it more, be careful not to exceed the limits of your setup though. Next mix calcium chloride with unspooled teflon plumbers tape and fill a largish longish diameter vertical column 1/5 with only teflon tape 'wool' then the remainder with your mix followed lastly with some paper towel. Gas enters from bottom comes on on top dry, you will lose some nh3 to the calcium chloride but this in no way impinges on it ability to dry this gas.
NaO is much much better, buy smallish marble chips, heat at greater 900 for at least an hour and ue as i intead of the mix.

jut realised my 's' key i dodge, apologies for all the mising 's's maybe we should hold a vigil for them

[Edited on 12-5-2011 by Panache]

smuv - 12-5-2011 at 07:25

CaCl2 is a very bad choice for drying ammonia, it forms a complex with it.

captaindrum - 12-5-2011 at 11:43

Quote: Originally posted by Arthur Dent  

Would plain pink glass wool do the trick?


I think it would. I use large granules in a narrow and long column, so they don't expand that much to crack the glass. Always working with small batches with those equipment may be my key to success though.


EDIT:
Quote: Originally posted by smuv  
don't use MgSO4, dont use CaCl2.

http://www.sciencemadness.org/talk/viewthread.php?tid=16061

I dont even know why I post my procedures.

Nice write-up and lovely setup BTW, Smuv!

Best regards...

[Edited on 12-5-2011 by captaindrum]