10-27-03 19:49
No 467051
I find gas soluabilities absolutely fabulous.
When 1 volume 40% meam was added to 4 volumes methanol why would the stir bar have bubbles forming on it after a few minutes? Given that methanol alone can hold up to 40% MeAm on its own shouldn't the gas have stayed in solution? The methanol was either reagent or HPLC grade >99%. I would think since you have 2 solvents that both can hold 40% meam gas at room temp that adding one to the other would increase soluability of the gas within the two. The temp of the mix was ~25c.
At the same time, without creating a new post I don't see the point in trying to gas methanol with meam since the solution will be so cold that the container will condense quite a bit of water in only 10 minutes. So, when this happens your going to have to dry the methanol anyway. The problem I'm curious about is when drying the methanol after gassing or addition of aqueous meam is: who really knows the truth behind how much gas actually stays in the solution? I'm reading one bee wrote running the solution through a column packed with MgS04/silica beads and then other's stating that the mgs04 will not only take the water out but most of the meam gas in that water too. I've found somewhere on the net where it stated the mgs04 will absorb water first followed by alcohols and amines. But does anyone know just how much if any is lost in the filter cake? It makes no sense to me that when you got 4x volume methanol able to hold 40% gas, why the filter cake should be holding any gas at all. Shouldn't it all dipserse uniformily?
Today, at the auto body shop I found 2 45kg empty barrels of this: http://www.oxychem.com/products/msds/m31
It's the first time I've seen a label (on the drum it said this) "Potassium hydroxide, Anhydrous, meets USP and food codex"
How can they claim anhydrous when the msds says 90%?
JIHAD!
(Chief Bee)
10-27-03 21:44
No 467074
When 1 volume 40% meam was added to 4 volumes methanol why would the stir bar have bubbles forming on it after a few minutes?
Did any methylamine actually boil out of the solution, or was this everything you saw?
Given that methanol alone can hold up to 40% MeAm on its own shouldn't the gas have stayed in solution?
What is your source for the fact that methanol can hold 40% methylamine at 25°C? I haven't seen that figure anywhere.
I would think since you have 2 solvents that both can hold 40% meam gas at room temp that adding one to the other would increase soluability of the gas within the two.
That isn't necessarily true, as the hydrogen bonds each solvent uses to dissolve the methylamine might be "used up" between the methanol/water bonding to each other, or some other phenomenon, so don't take that for granted in all cases.
I don't see the point in trying to gas methanol with meam since the solution will be so cold that the container will condense quite a bit of water in only 10 minutes. So, when this happens your going to have to dry the methanol anyway.
You aren't supposed to leave the chilled methanol open to the atmosphere, attach a drying tube filled with anhydrous calcium chloride to the flask holding the solution so that no water condenses in it.
mgs04 will absorb water first followed by alcohols and amines. But does anyone know just how much if any is lost in the filter cake? It makes no sense to me that when you got 4x volume methanol able to hold 40% gas, why the filter cake should be holding any gas at all. Shouldn't it all dipserse uniformily?
MgSO4 may bind amines because it is slightly acidic and amines slightly basic - Your "uniform dispersal" theory has no scientific merit.
How can they claim anhydrous when the msds says 90%?
The MSDS didn't say that the other 10% was water, so it is probably potassium carbonate.
(Stranger)
10-28-03 00:52
No 467133
That isn't necessarily true, as the hydrogen bonds each solvent uses to dissolve the methylamine might be "used up" between the methanol/water bonding to each other, or some other phenomenon, so don't take that for granted in all cases.
The phenomenon of solutions of gas in solvent is that the intermolekular bindings between gasmolekule and solventmolekule is strong enogh to prevent the gasmolekule to go in the gasphase. These Bindings can be Acid/Base or v.d.W.-Bindings or chelates or else.
MeAm (g) in MeOH will probably be a Acid/Base one.
As we know that H2O (which is the most impurity in MeOH)is more protic as MeOH it will increase solubility of MeAm.
who really knows the truth behind how much gas actually stays in the solution?
to scram:
try a quantitative titration of your MeAm solution .....
(Hive Bee)
10-28-03 18:25
No 467312
About 5 minutes after adding the 1 vol 40% to the 4 volumes methanol the stirbar had several bubbles forming on the surface. That was pretty much it.
Chemfinder shows TCI with methylamine in methanol at a 40% weight. Maybe I'm wrong in assuming that this is not a refridgerated item.
(Stranger)
10-28-03 22:42
No 467378
But i dont understand:
after adding the 1 vol 40% to the 4 volumes methanol
Is it right that u used 40%MeAm/H2O solution and add this to 4 volumes MeOH ?
Best way to make a MeAm/MeOH solution ist to gas MeAm through the MeOH. In this way a 2M solution is the highest concentration economical. 2M solution is about 8% mass or less.
(Hive Bee)
10-29-03 14:20
No 467508
Yes Aldrich 40% d20 on bottle claimed 0.902 and this was measure and showed correct. As stated earlier the MeOH was a minimum of 99%. I think it only had a max 0.005 water in it. This is what was done: 465 - 470 ml of the MeOH was put into a flask. Added to this was 114 ml of the meam. The bubble formed on the stirbar after a few minutes, very little of them acutally popping off and floating to the top. 75g dried MgS04 added the flask and stirred for 35 minutes. Vaccuum filtered the solvent to get a clear solution smelling strongly of MeAm with ph ~9 to 10. The filter cake was evidently still dry, did not congeal and still fine and granualar. Total volume after drying 520ml. d20 went up from 0.787 to 0.835 (??)
The next day this 520 ml was put back in the oven dried flask and added another 86ml Meam. no bubbles forming on the stirbar this time. 75g dried mgs04 added and this time stirred for nearly 2 hours. The strange thing is that this time the mgs04 became very congealed and mushy indicating that there must have been much more water present on the second run or the first run of 35 minutes just wasn't long enough. This was nearly impossible to buchner because of the consistency of the msg04. It just would not suck through at more than 1 drop every 3 seconds. I know no other way of speeding this up (possibly other than freezing the whole mess to hopefully think that the mgs04 will bind together at the bottom of the flask.
(Newbee)
10-29-03 18:01
No 467572
Ok i understand that u need a waterfree MeAm/MeOH solution?
Do u only have MeAm/H2O solution ? Whats about MeAmHCl ? Cant get this ?
If u can get it try this :
Solute the MeAmHCl in MeOH and add NaOMe to free the MeAm.
Best way is to give NaOH solution to solid MeAmHCl and let the gas go through MeOH.
U can make MeAmHCl from MeAm/H2O solution quite easy:
Add konz. HCl to the solution till neutral. Evaporate the Water. Solid residue is MeAmHCl.
The Bubbles u have seen at your preparation is MeAm (g) and it is formed because soluability of MeAm in MeOH is much less than soluability of MeAM in H2O. The way u discribed to make the MeAm/MeOH solution is quite unusual.
When u buy MeAm/H2O solution from aldr... ? why u dont buy directly a MeAm/MeOH solution ???? Cheaper ......
Good Luck
(Hive Bee)
10-29-03 23:42
No 467664
"When u buy MeAm/H2O solution from aldr... ? why u dont buy directly a MeAm/MeOH solution ???? Cheaper" It's not a matter of buying, but what's available.
Why the hell would I want the salt over the 40%. That would be counterproductive. Nor would I think that changing it to the salt would make things easier. If I wanted to truely gass then I would simply make a gassing rig and dump straight naoh in and heat the solution with vapours going the dri-rite. It's just a pain in the ass to gass sometimes. I never heard of NaOME
http://chemacx.cambridgesoft.com/chemacx
(Newbee)
10-30-03 20:01
No 467838
I never heard of TCI before but this percentage is unbelievable and unserious.
U never heard about NaOMe ??
I think this reaktion is quite possible:
MeAmHCl + NaOMe --> MeAm + NaCl + MeOH
NaOMe is NaOCH3 or Sodiummethylat or CAS [124-41-4].
And again : highest concentration of MeAm in MeOH is 2 M = 8%
And gassing MeAm in your MeOH is the easiest way (drop NaOH solution to solid MeAmHCl). Use some gas-washing-bottles. All other preparations will be impure.