xwinorb
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Problem with MeAm.HCl shelf life
Noticed the following :
MeAm.HCl, 500 g, 95 % purchased in 2001 from a local retailer; from Fisher.
Product initially OK, had a distinctive fishy odor, not very intense.
After a couple of years, stored in fridge at aprox. 5 C :
Used several times, remainder of product lost some of the fishy odor. Still reactive, producing a lot of fumes when neutralized with NaOH solution.
Then, a few months stored in a closet, exposed to heat. maybe as hot as 45 C during the day. Then moved back to fridge.
After that, fishy smell essentially gone, a lot less reactive when neutralized with NaOH. Also, low yields and byproducts.
I do believe this relates to MeAm.HCl having somewhat degraded, specially when exposed to heat. Would like a confirmation of this please.
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xwinorb
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More info
Forgot to say, product allways inside air tight bottle, well closed.
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transformer
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I cant say if your methylamine HCl has decomposed but the stuff does not have a real odor so smelling is not an indicator perhaps there was a trace
ammount of methylamine in its base form present that gave the odor your described?
Also i have never seen moderate heat to cause methylamine hcl to decompose, you can even sublime it under vacuum at 230 celcius.
[Edited on 12-11-2005 by samsung]
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xwinorb
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Follow up
Run a comparison experiment, using nitromethane as MeAm source, everything else the same, as much as I can tell.
Good output, nice, clean, no strange byproducts. Yield a bit on the low side, attributed at least to bad workup.
Also, reaction started nice and easy, quite exhotermic. When using the MeAm.HCl had to apply heat for a log time to get it started.
I am convinced there is something not OK with the MeAM.HCl, and it has to be some sort of product degradation during storage. It was OK when
purchased.
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apatzingan
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fishy odor?
I don't think that the salt would have a fishy odor. Are you sure you don't mean the base? Can't imagine the salt wouldn't last if kept moisture
free.
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Drunkguy
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I remember seeing a bottle of MeAm.HCl in my lecturers lab unattended quite a few years back. Let's say while I was not tempted to theive it, the
thought certainly crossed my mind.
But my point in this post is that the appearance was not bright white and crystalline, more yellow and mushy. Maybe you should try using a larger
excess if it has absorbed significant quantites of water from the atmosphere. I hear what you are saying though, its just I cant think of what the
degradation pathway might be. Who knows? That's anyones guess not mine.
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xwinorb
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Just after being purchased, the MeAm.HCl was sticking to the bottle, solid, white, crystaline, subtle ( not strong ) fishy, amine smell. I remember I
had to scrap it out of the bottle with a screwdriver.
After the moving, storage place change, etc, as described before, it was still white, looking a bit more like snow, a bit lighter than before.
Have seen conflicting reports on smell, some saying it is odorless, some others like me confirming it has a fishy, amine smell.
As I have mentioned before, the smell now is much less noticeable. When the MeAm.HCl was new, have used it several times with good results.
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