mericad193724 - 30-9-2006 at 14:05
Hello,
I just bought a 300 mm graham condensor. After I used it for distillation I washed it with water, but now the coil and jacket still have drops of
water in it and this is bad if you are distilling anything exept water itself. Can I put the condenser which is slightly wet into a conventional oven
found in most kitchens to remove the water. The reason I am asking is because I don't know if the wet glass will be prone to cracking even at 100C
(lowest oven temp). Is this OK or am I going to be inducing stresses in the glass of the condensor and cause it to break or weaken.
Mericad
hinz - 30-9-2006 at 15:22
If you have a big enough oven, this will work unless your glassware is the biggest crap.
Thermal cracking will only happen if you heat a piece of glass at one point and leave the rest cold, so the glass will expand at the heated point,
which gives thermal stress.
I've killed one RBF by this way, I had a solid layer of some inorganic compound(NaHSO4/Na2SO4 from HNO3 destillation) and heated this with a bunsen
burner(I knew that something thelike might happen, so I was quite careful, I'll never do something aggain, learning by doing
, i use an oil bath instead). This caused the bottom of the flask to get much hotter
than the rest of the flask, the thermal stress from it broke it.
If one piece of glass doesn't fit in your oven you might also wash it with acetone, MeOH or any other low boiling solvent and blow through it with an
hair dryer.
[Edited on 30-9-2006 by hinz]
evil_lurker - 30-9-2006 at 15:49
Oven should be fine.
Acetone would be quicker, or even Isopropyl alcohol.
Heat guns will work too.
not_important - 30-9-2006 at 23:09
The secret is slow heating and cooling, a mild thermal gradient isn't a problem so long as it isn't set up too quickly. So putting it in the oven with
the door cracked, the turning the oven on low, when done turning the oven off, close the door and let it cool down, will work fine.
You want the oven door slightly open to let moist air out. Lab drying ovens typically have vents to get slow drafts.
Even blowing room temperature air through it will eventually dry it.
And using acetone or IPA to hasten the drying works too, but does waste a little solvent.
BTW, when working with water sensitive substances, it is typical to heat them for 1/2 to 2 hours in a oven at 110 to even 200 C.
bhassi - 1-10-2006 at 06:58
The best way would be as following:
Rinse the condensor with low boiling point organic solvent (of highest purity) like methanol or acetone (better) thoroughly. Now keep it in a hot air
owen set at around 40-50 degree Celsius for a couple of hours. Nothing wrong will happen to the glassware if it is of acceptable quality. No guarantee
for the crapy stuff. Please ensure that the organic solvent to be used is of atleast HPLC grade or higher purity as lower purity solvents may contain
impurities which can contaminate the condensor.
mericad193724 - 1-10-2006 at 12:13
Thanks for the input everyone.
Rinsing with any solvent but distilled water won't work for me because I have nothing of high purity. "At lest HPLC grade"...HaHA...the purest Low BP
solvent I currently have is HEET Brand antifreeze - 99% (MSDS says other 1 percent is an industry "secret.") This week I am making anhydrous isopropyl
alcohol.
I like the heat gun Idea(hair blow dryer), I will try it right now and if the condenser cracks I will FLIP OUT...and then I will hunt down whoever
suggested the idea (Evil_Lurker)...I know where you live 
Mericad