07-15-04 14:16
No 519554
Hello all you lucky elfs out there.
I noticed that in many synthethic routes there comes the need o perform some or all procedures under a constant stream on nitrogen.
I asked around and a dude told me it is to avoid moisture in the air. Is this true?
If so could one simply use a big drying tube (with MgSO4 in the bottom) in which all the reactions would take place?
If not what would be an adequate replacement for mimicking a nitrogen atmosphere?
Thanks!
(Chief Bee)
07-15-04 14:33
No 519563
I asked around and a dude told me it is to avoid moisture in the air. Is this true?
In some procedures that's the reason for using an inert gas, but just as often the reason is that either the reactants or the product is highly sensitive towards oxidation, and will even react with the oxygen in the air. Examples of such reactions are those involving phenols in basic solution, many organometallic reactions as well as the delicate operations involved in LSD synthesis.
Whether a drying tube is enough, or if the inert gas is indispensible, it simply varies between different reaction types.
The Hive - Clandestine Chemists Without Borders
(Stranger)
07-15-04 14:40
No 519567
Thanks so much rhodium.
So for a synthesis of our good friend ALiceD, what would a ghetto laboratory do to replace the nitrogen flow to avoid oxidation?
If Nitrogen gas was obatainable, how would one go about and set it up? Would it be enough to put the exhuast tube from the nitrogen bottle directly over the flask of the reaction in a fume hood or some other setup is required?
Thanks again!
(Hive Bee)
07-15-04 19:49
No 519611
If you can't get a tube with nitrogen gas, how do you think you are going to aquire all the other reagents/precursors? Nitrogen seems like one of the smallest problems involving the synthesis of LSD.
(Newbee)
07-15-04 22:43
No 519647
local brewery shop - for N2/CO2 mix or hydroponics for straight co2 - or for welding (sp?) - steal a cannister from the local pub - easy peasy pissy easy
if you can get pocl3 - phosphorous oxychloride then i can offer ergotamine tartrate
also think of wave lengths of light that you work under...
(Hive Bee)
07-16-04 05:20
No 519694
welding supply is prolly your best bet. not sure about in all cases but helium is also a noble and isn't likely to react with much and it can be gotten at the walster 24hour mart for likie 20$ for a 10 pound tank.
(Hive Bee)
07-16-04 06:05
No 519698
helium is also a noble and isn't likely to react with much
Wont react but could you contain it in the vesseL? helium is really light, Ie it will raise up and get lost if you dont seal the reaction vessel....
Argon is a much better idea (MIG welding??) its nobel gas (wont react) and its actually heavier than air so (for a reflux under inert atmosphere) you just pump in argon into a side port of the flask and it pushes all the air out the top of the condenser. The argon will sit on the reaction materials shielding them from air.
-AC
Its just my opinion, but no-one listens to me anyway, and rightly so...
(Hive Bee)
07-16-04 06:45
No 519704
but just for the record i was envisioning a sealed rxn and was more concerened with trapping the gases inside low in the reflux. i.e. he helium being lighter would be at the top of the reflux and would be filling the balloon atop instead of the HI.
(Hive Bee)
07-16-04 08:48
No 519721
If that was your intentions (to protect the balloon against HI attack) you could mix your inert gases...
Argon to cover the reaction and helium to raise up and protect the balloon.
Best method would be as i said to flood to reaction vessel with argon via a flask side-port and thereby pushing the air out the top of the condenser, the attaching your balloon to the top and then let helium into the side port where the argon went in... this would then rise to the top protecting your balloon.
Is that what you were thinking?
-AC
Its just my opinion, but no-one listens to me anyway, and rightly so...
(Stranger)
07-16-04 20:35
No 519776
Argon sounds like a very good idea. Thanks for your help.
One more question though - If 1 would do a rxn, where he had to boil some solvent away, but didnt not want any moisture or O2 from reacting wiht the rxn materials, could he just pump in argon and it will stay there while boiling or the fumes would push it away? He could just keep on pumping argon into the rxn vessel but that seems like a waste. How would you suggest 1 could go about it?
(Wonderful Personality)
07-17-04 03:40
No 519809
As long as you are boiling away solvents, how should there come air or moisture to the soup? The solvents will fill the flask for the boiling creates some overpressure, thats actually how distillation works.
When you shut down the heat, then you should have a moisture protection tube filled with CaCl2 or similar or if air (oxygen) is to be avoided you can use nitrogen or argon.
Argon from welding supplies has often oxygen added (ARGOX is a trade name for this). Take care to get pure argon, it is available. Check the suppliers webpage for product number and uses before you go/call there. This makes things much easier
.You should also know before what armatures you need, pressure reducer etc.
(Hive Bee)
07-17-04 07:15
No 519837
Argox is used with some kinds of MAG welding, and SCUBA diving.
Straight argon is used as a shielding gas in TIG welding which is helpful.
C-25, a 75% argon 25% co/2 mix is probably the most common and is probably the most commonly used gas with MIG/MAG welding hobbyists.
Technically you'd use a helium argon mix for "true" MIG welding though.
..we've got to help each other out Cause this is how we all survive..
(Hive Bee)
07-17-04 09:23
No 519859
more to help keep the HI in the flask by acting like a blanket i guess... but protecting the baloon is a valid concern that may also help.... isn't HI heavier than argon too though? me thinks it is, so i spose the same thing would be achieved with an argon filled condensor/flask setup....
(Hive Bee)
07-17-04 12:20
No 519878
I don't believe that the vapour pressure of the boiling solvent will eliminate all of the moisture that can enter the apparatus through diffusion. That is why the CaCl2 drying tube is used which should be no problem
fear fear hate hate
(Hive Bee)
07-18-04 12:17
No 520059
in distillation for nill moisture just the vp of boiling solvent would not keep out all of the moisture, using a 3-way adaptor connected to the distillation reciever with the CaCl2 drying tube would suffice to prevent moisture.
-AC
Its just my opinion, but no-one listens to me anyway, and rightly so...