Dr.Arz
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Large glass wine flasks?
I visited brewery shop some time ago and I saw there huge flasks like round bottom ones which came with basket. They were used to store wine and beer.
I believe they are made of soda glass but I began to wonder if they could be used for larger volume low temperature reactions? They dont have ground
joint mouths of course but one could take silicon plug or teflon rod and turn or drill hole for reflux or distilling column.
When I was a kid I used to boil sulfuric acid in pyrex containers. They stood that as long as they kept hot, but the time heating was stopped they
almost always cracked. One study finds that critical temp for soda glass is 270C and surface temp is 60C(like water shock). But could one use these to
distill like acetone or alcohol?
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Dr.Bob
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I have used real Pyrex for years without problems of cracking. Vycor is even better, but pricey, but they sell beakers in it for real temperature
issues. If you are planning on heating anything flammable or corrosive (like acetone or acids) I would spring for the real Pyrex glassware with
joints. You can buy small kits of 24/40 glassware for as little as $100 for Chinese or used Pyrex.
For ethanol, you can also use metal equipment , but only if done well, otherwise it will leak or make a mess. Most wine bottles are thick, and the
combination of thick glass and heat will almost always crack the glass. Plus most corks, stoppers, caulk, etc will leak quickly in real life. And
with a non-glass condenser it is very hard to tell if the distillation is going properly.
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Dr.Arz
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Thanks for your advices, but I have full set of Schott glassware up to 5000ml flask size. I also have some stainless equipment.
My question was that how suitable soda lime glass flasks would be for running voluminous reactions, like something that requires 20ml of solvent per 1
gram of reactant, in room temperature.
Silicon plugs work very well actually, I have used them for several instances like making a DIY buchner suction filtering device by drilling two holes
for funnel and vacuum tube. I also have made throughputs for thermometers and other stuff with them with zero failures.
But is it just not advisable to heat anything with soda glass? The flasks are not wine bottles in their shape, but actual round bottom flasks. The
purpose for this is that a 20-liter flask costs only 15.
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Dr.Bob
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You will have to do a risk assessment of the situation. If you are not heating, or heating very gently (eg, not with a flame, but with a water or oil
bath) it may be better, but I would only consider that for something that would not be dangerous if it spilled, like water solutions. Also, if you
are doing this outside away from things then it would be less hazard.
What scares me is the people doing chemistry in soda glass containers, heating on their stove, on large scales, and with their kids upstairs. I have
seen too many stories of that type of accident over the years. So use common sense, if you want to distill ethanol from a 20L flask, make sure that
it is outside and away from things that burn, so if it cracks, you don't burn the house down.
If you find a way to heat them gently, the stoppers you use stand up to the chemicals, then it might be OK, but never as good as using the proper
equipment would be. I have seen people break even Pyrex with harsh heating, so I am quite sure that soda glass will not take too much stress, but
they sell baking dishes made of soda glass now, and only a few break of thermal shock each year, so it just depends on your willingness to take risks
and what you are doing. But please look at the overall safety of the experiment and decide.
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careysub
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Quote: Originally posted by Dr.Bob  | | .. but they sell baking dishes made of soda glass now, and only a few break of thermal shock each year... |
But these (made by Anchor Hocking or World Kitchen, which uses the deceptive "Pyrex" label for this non-borosilicate product) are made of specially
tempered glass. Ordinary soda lime glass would be far more heat stress shatter-prone.
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