loveoforganic
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Drying sensitive primaries
Hey guys,
I was wondering what you all generally did to dry primaries which are rather sensitive (AP, fulminates, silver carbide, etc.). I live in the humid
south, so just leaving on the filter exposed to air hasn't been too effective, and I'm not a big fan of leaving such a compound sitting unsupervised
for prolonged periods of time. I suppose a double ziploc bag dessicator would be a decent option (e.g. mag sulfate in one open ziploc placed inside
another larger ziploc with the filter paper/compound in it)?
TYIA
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avi66
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Dear loveoforganic, it is Ok to use a sealed bag with desiccant, but it is much more effective to use sealed device(using vacuum) with your desiccant
agent and primer inside, it will increase to rate of the primer dehydration, i already try to use a sealed device only with desiccant agent and its
take 10x times longer then using my vacuum desiccator, im using 0.05 bar vacuum using CaCl2 desiccant agent which is very strong desiccating agent
with respectively water capacity.
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User
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If you dry the material as far as possible by means of vacuum filtration it will save you a lot of trouble.
I encountered a few problems myself especially with silver carbide and similar substances.
The annoying thing about these materials is that the don't really form a crystalline matter.
I don't know if it is because of this behaviour but it tends to cake and crack upon drying.
Resulting in large particles that are rather brittle and tend to dust.
Nasty stuff to work with imo.
Also when you work with explosive materials I would suggest not to use glass.
For example and old (plastic)paint bucket filled with absorbent works well for these purposes.
I also share your nature when it comes to leaving sensitive materials unwatched.
Just doesn't feel right... somehow.
[Edited on 8-2-2011 by User]
What a fine day for chemistry this is.
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SB15
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Washing with isopropanol and drying in open air usually does the trick for me. I store most primaries under isopropanol to reduce their sensitivity,
then dry out small amounts immediately before assembling a cap.
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loveoforganic
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Thank you all for the advice. I don't have a vacuum desiccator unfortunately. For drying as best as possible on filter over vacuum, this has made me
nervous in the past with the ceramic surrounding the compound. I suppose this may be needless worry though, given that moderately dry primaries I
obtain still require a fair bit of time on a spatula over a flame to pop, yeah? That would be a good option if there isn't much need to worry. I'll
try the isopropanol wash as well.
Thanks again!
Edit: I agree about silver carbide. It also has had a nasty habit with me of rising up and sticking to the test tube I synthesize it in. Can't
remember the verb, but it's similar to what happens in a chemical test that forms a red copper compound, though I can't remember the name of that test
either!
[Edited on 9-2-2011 by loveoforganic]
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Arthur Dent
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If you kindly permit me to derail this thread ever so briefly, I do have a Pyrex vacuum dessicator, and quite a few ground glass joint glassware I
recently acquired. I was looking to buy some vacuum grease and that damn stuff is expensive and hard to find! 
So in my never-ending cheapskate quest to save a few pennies, I was looking into my toolbox and I found a large tube of silicon dielectric grease, the
stuff used to lubricate automotive electric contacts exposed to the elements. It has a very thick consistency, is made of silicon, and does not melt
when heated... It looks and feels exactly like real vacuum grease! Could I use this stuff to seal my dessicator and my other ground glass joint
glassware?
I do intend to use my brand new dessicator very soon, I even have a big bottle of indicating drierite ready to be used!
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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User
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Indeed kinda of offtopic, anyway.
The material your describing seems usable.
You could check out MSDS sheets to find out what it is made of etc.
Be aware of possible side reactions and especially when it comes to very reactive products.
Myself I use regular petroleum jelly when this is possible.
For high vacuum and "dangerous" reactions I suggest you stick to the real deal.
I have one tube of highvacuum grease,Iwonder if Ill ever need a new one in this life time.
What a fine day for chemistry this is.
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Arthur Dent
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Thanks for the tips!
Yeah, I didn't want to waste bandwidth by starting a thread just for that. I'll try your suggestions. 
Now back to our regularly scheduled primaries thread! 
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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DNA
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Anyone got an idea how to clean out lead azide from a beaker?
It dissolves in acetic and nitric acid, but that would give hydrogen azide which i don't really like.
Any ideas how to clean it safely?
It really sticks to the glass...
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quicksilver
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Quote: Originally posted by DNA  | Anyone got an idea how to clean out lead azide from a beaker?
It dissolves in acetic and nitric acid, but that would give hydrogen azide which i don't really like.
Any ideas how to clean it safely?
It really sticks to the glass... |
Northeaster University has a protocol:
DEACTIVATION OF SODIUM AZIDE
Sodium azide is among the P-listed hazardous wastes regulated by the US Environmental Protection Agency. As a discarded commercial chemical product,
off specification species, container residues or spill clean up material, it must be managed as a hazardous waste. Dilute solutions (5% or less)
managed as part of your experiment protocol can be destroyed by reaction with nitrous acid, which is freshly prepared. Massachusetts regulations do
not allow sodium azide to be deactivated (treated) outside your experiment and away from the point of generation.
2NaNO2 + H2SO4 ® 2HNO2 + Na2SO4
2NaN3 + 2HNO2 ® 3N2 + 2NO + 2NaOH
The operation must be carried out in a chemical hood due to the formation of nitric oxide. An aqueous solution containing no more than 5% sodium azide
is put into a three-necked flask equipped with a stirrer, a dropping funnel, and an outlet with plastic tubing to carry nitrogen oxides to the
laboratory chemical hood flue. A 20% aqueous solution of sodium nitrite containing 1.5 g (about 40% excess) of sodium nitrite per gram of sodium azide
is added with stirring. A 20% aqueous solution of sulfuric acid is then added gradually until the reaction mixture is acidic to pH paper.
Caution: This order of addition is essential. If the acid is added before the nitrite, poisonous volatile HN3 will be evolved.) When the evolution of
nitrogen oxides is over, the acidic solution is tested with starch-iodide paper; if it turns blue, it means that excess nitrite is present and
decomposition is complete. The reaction mixture can safely be washed down the drain. Note that the solution must be neutralized with dilute NaOH
solution to pH 6-9 prior to discharge.
Obviously there are simpler means but a complete understanding is essential. LD50 is similar to cyanide, therefor it should be treated as such when
cleaning glassware.
Neutralization of energetic lead azide for cleaning may be accomplished via standards (see above complete MSDS for NaN3) polar solvent may then be
used to clean glassware but treated as a serious toxin and at no point allowed to contact skin or mucus membranes. Obviously cheap disposable bottle
brush used one and disposed as per toxins Whetted material brushed with soft item would not pose friction risk against smooth glass; static would be
accessed via whetted azide.
Protocol should be retained as Na azide is used frequently in certain conditions (dialysis & fungal cleaning, bio-labs, etc)
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