zenosx
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Hardest Glassware to Clean
After spending the last two weeks attempting to get a 100mL 3neck flask clean, I was curious just what was the messiest/gunky/unremovable crap you
have had to deal with in the lab, and maybe what you were working with to develop it.
Mine started with a benzyl alcohol chlorination to benzyl chloride. The reaction went forward great, and the yields weren't bad.
The mess came on distilling the benzyl chloride.
Perhaps it's the high 179 C B.P. that caused the gunk. My product on distillation was fine, but a viscous yellow oil was left over. I should have
dumped it immediately but it hardened into the most nonreactive gunk ever.
This flask has been soaked in Conc. H2SO4, Conc. HCL, piranha solution made with 20% H202 and Conc. H2SO4. (From the horror stories I made REAL sure
there was no acetone in there, and applied with the glass behind a blast shield + the usual PPE.)
So far the list goes on:
Acetone
70% HNO3
Gasoline
Kerosine.
Not to mention a LOT of scrub scrub scrubbing!
Been through my washer 3 times.
The sulfuric reacted with something to give a nice coating of a white (sulfate?) of some kind that is just as tenacious.
Tomorrow I am going to hit it with the Bunsen and see if high temps will oxidize/burn/carbonize/melt or otherwise DESTROY my new menace!
A question that sometimes drives me hazy: am I or are the others crazy?
Albert Einstein
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Mailinmypocket
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Try using a strong solution of KOH in isopropanol, Member kristofvagyok mentioned it in another thread not long ago and I just so happened to have a
problem like yours. It was after a Friedel Crafts reaction and messy crap just wouldn't come off the bottom of the reaction vessel. 30 minutes with
the alcoholic base solution and it dissolved right off! 
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zenosx
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I do think I will try that first. Thanks!
BTW I had UTFSE but I didn't come across anything particularly useful that I hadn't already tried for those out there itching to flame 
A question that sometimes drives me hazy: am I or are the others crazy?
Albert Einstein
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kadriver
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Try boiling aqua regia - 4 parts concentrated (32%) hydrochloric acid and 1 part concentrated (68% to 70%) nitric acid.
Do it outside or in a hood as the fumes are poison.
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zenosx
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If the KOH doesn't do the trick I'll try the aqua Regia. I am not such a newb that I'm not aware of the poisonous NOx gasses thankfully, but thanks
for the advice.
A question that sometimes drives me hazy: am I or are the others crazy?
Albert Einstein
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hyfalcon
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Piranha solution if all else fails.
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phlogiston
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In general, try a wide variety.
Polar/apolar solvents
acidic/alkaline solutions
Strongly alkaline indeed seems a good thing to try next, as you used only strong acids and various solvents so far.
Concentrated bleach also does a good job sometimes.
-----
"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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Ephesian
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I would try DMAc, works great for cleaning glassware
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zenosx
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Well I have made up an isopropanol and KOH solution of fairly high concentration. When I get home tomorrow I am going throw some heat to it and see
what happens. It's soaking @ RT atm with this solution.
I had already tried piranha solution, although it wasn't full strength, only using 12% rather than 30% H2O2. I have had a hard time acquiring 30% H2O2
(or 30% NH3 for that matter) at my location.
I hadn't tried alkaline solutions at all yet, so thanks for everyone's advice there. I am not sure why I didn't think about it myself. Sometimes it's
easy to get on a one track thinking pattern, and busting that box can be hard to do without outside help.
I'll post back as to what actually managed to rid this rather expensive piece of glassware of it's infection. While a $30 flask isn't much to some, I
have learned from this forum that some of the home chemists have that as an entire budget for a reaction. If NO soaking works, I plan to heat it over
a Bunsen to oxidize / carbonize whatever is in there. From the initial reaction, it SHOULD have been organic, which I figured Piranha would have
decimated, oh well.
I only wish I had a lab partner in my area besides my unwilling wife, who does at least help me IF I need it. She may not smile, but we get the job
done LOL!
BTW I apologize for being rather verbose in any responses here. I tend to type fast, and think fast, even if my thinking isn't on par to reality
A question that sometimes drives me hazy: am I or are the others crazy?
Albert Einstein
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The_Davster
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Get some coarse salt. Like the stuff for roads. Fill flask 1/4 with salt. Add acetone until the salt is soaked. Shake the fuck out of the flask.
It just uses the sharp edges of the salt to scrub to flask. I have never found anything this will not clean.
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phlogiston
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Perhaps there is actually some value in the crap you made as an inert coating with good adherence. Could be useful for all kinds of things if you
could make it on purpose. A bit like teflon.
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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zenosx
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Well the con. KOH solution did the trick. Thanks for the help.
After soaking overnight, the gunk is just falling off now. Ill remember alkalis next time instead of just acidic cleaning solutions no I didn't
measure it out so have no idea of conc. about 3 sm lab scoops ~5g to 100mL isopropyl alcohol I'd say.
[Edited on 21-2-2013 by zenosx]
A question that sometimes drives me hazy: am I or are the others crazy?
Albert Einstein
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Dr.Bob
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I have been using a base bath to clean dirty glassware since I started chemistry ~30 years ago. We do this at work often. A large Nalgene or PP
tub with a lid is best, and it takes about 2 gallons of either iPrOH or EtOH plus a pound or so of NaOH and a little water. The ethanol is
hydroscopic and many of the items are washed in water first to try to clean, so the amount of water goes up with time, thus I tend to start with less
than recommended. I let stuff sit overnight and then rinse carefully with water and then rewash with soap, water and acetone. Most flasks come
out gleaming clean.
Of course, this will eventually etch the glass, lower the tare weight, and after about 20 years of cleaning, weaken the glass. We have glassware
that has been treated this way for years with no real sign on damage. Of course if you get this on your hands, jeans, or labcoat, they will get
etched notably faster than the glass, so that is where I focus my attention on safety. I have ruined two nice sweatshirts this way, when the liquid
splashed on my gloves and got on the cuff of my sweatshirt, and I did not notice. But if you get it on your skin, it will burn it quickly, with that
soapy feeling that base burns produce. I have only had a very minor incident that way, and washed my hand for a few minutes and it was barely even
bothered.
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zenosx
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Thanks Dr. Bob. Until I started this thread, the idea of using high alkaline solutions didn't cross my mind for the etching reasons you mentioned. I
have stored a concentrated solution of NaOH at 20'C in a Florence flask, that I forgot about for several months, and it shows no signs of damage. I am
sure the glass interior is ever so slightly thinner, but I agree with you, that unless you are working with molten NaOH or similar, the etching is
minimal.
I am still a newb when it comes to chemistry and am not afraid to admit it. I have a lab that many on this forum would die for, but I just have more
funds to work off of than some of the younger up-comers I suppose. As such, the idea of using alkaline solutions for cleaning never crossed my mind,
probably from reading so many articles on piranha and other mineral acid solutions for cleaning.
If I had the facilities to create a permanent base bath I would do so, but like many amateurs on this forum it isn't an option. I do however plan to
mix up a iPrOH + KOH or NaOH (or EtOH as you mentioned) wash for use during cleanup. I have been building this lab now for 2 years, and this was the
first time I ran across something so hard to remove.
I have experienced my share of the "soapy base burns" so I know what you mean Dr. Bob. I keep a nozzled water hose and a bucket of water on hand at
all times. It has saved me more than once for unexpected acids or bases that splashed or otherwise got onto areas I did not want them on.
I will also say that I have no want to work with Benzyl Chloride in the lab again, it's a bad lachrymator on even the smallest spills, and any
glassware that contained it had to be kept outside until cleaning or the entire house would stink. I also somehow got the tiniest amount on my finger
even with gloves, and later rubbed my face. Needless to say I was spraying and washing my face for 15 mins afterwards, I think the burning was mainly
due to the fact I had just shaved a few hours before ... OUCH>
Thanks again everyone. I have learned much from this thread that I expected honestly to be ignored, or flamed. Even something as silly as cleaning
glassware can be a challenge now and then. The moderators can move it if they want, or,
If there are others with issues like mine to post, I'd be happy to hear how you dealt with them, and what you were working with at the time.
A question that sometimes drives me hazy: am I or are the others crazy?
Albert Einstein
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zed
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Ice cubes and Dutch Cleanser. Sand, ball bearings, or BBs, and whatever solvent you wish to try. Shake baby shake.
Gunk is sometimes very difficult to dissolve. Cleanings that have a mechanical component can be helpful. Abrade it off!
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Hexavalent
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I'd be a trifle concerned about this setting fire/exploding anything organic or combustible...
Personally, I have worked miracles by shaking salt and acetone in flasks...they go in filthy - horrible mixtures of decomposed organics, failed
inorganic complexes etc. - and come out gleaming. Moreover, the acetone can be filtered off and used again for this purpose..I keep a small quantity
of acetone in a bottle for this purpose: use it to clean, and back it goes for another run someday.
[Edited on 10-3-2013 by Hexavalent]
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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ScienceSquirrel
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Thread Split
18-3-2013 at 10:19 |
daragh8008
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Anybody got any tips for getting brown manganate crap of glassware. Just can't seem to get rid of it
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unionised
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Tried lemon juice?
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daragh8008
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Nope but I will now
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The_Davster
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See my salt/acetone post above
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Vargouille
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Brown "manganate"? Sounds like MnO2. The way I get rid of it, for I get such stains occasionally, is to dissolve sodium thiosulfate in grocery-store
distilled vinegar. It's cheap and effective, since MnO2 is most oxidative in acidic solutions. You can buy sodium thiosulfate as "bleach stop" at
dyeing and photography stores, and it's a good, all-purpose reducer.
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