I felt the urge to write a few things down.
I hope they'll be useful to you guys.

a list of general chemical techniques

1. Non-pyrex glassware

If you add hot water to glass, it will crack. Always heat your glassware first, or, with some care, add a few drops allowing the liquid to heat the glass. swirl, add some more.

2. Heating solvents

Solvents should only be heated in a water bath and never over open flame. However, the case of small recrystalisations, the volume of solvent used is low and this may be permissible. Never evaporate solvents in an attempt to collect the product this way.

3. Pressure, Heat, Volume

When dealing with pressurised containers, you must make sure that vessel is suitable. If you are rigging a pressure cooker for steam distillation, be sure it is suitable and the gasket is intact.

4. A general technique

Useful techniques are to collect all simmelar residues and washings in a single vessel, which may be recollected and purified later.

Chemistry can sometimes be messy, So try to give thought to the area you will be working in. Solvent spills will evaporate yes, but some liquids stain. Some compounds are irritant, and these are not something you want spread around in your general environment.

5. Speed evaporation

It is permissible when evaporating organic solvents, to use an electric fan heater. Generally this technique is fairly safe, assuming that you add a second ventilation fan, and make sure that the area is well ventilated. Evaporation of 100 - 150ml naptha can be achieved in 2 hours or less this way.

6. Anti-bumping granules

Should be used to facilitate steady boiling

7. Practice by doing

The following techniques should be practiced, not researched. You will learn more by doing. Try to rely only on your judgement and your knowledge and you will find that you return to the reference material less frequently or to discover something new.
a. Recrystallization
b. Freeze-Precipitation
Both of these techniques depend on an excess of product being dissolved in hot solvent. If crystalline, heat the product first and then add the smallest volume of solvent possible.


If anyone else has more to add to this, go right ahead

Never throw out/dump anything until you have your final product.

some general good tips, shoe.. though I would definitely NOT recommend heating flamable solvents, no matter how small quantities, with open flame, no way!!! I even think you should edit

Ill probably think of something more to add later, but I should sleep... nice thread!

Is heating solvents on an electric heating element alright to do?

How do you setup a steam distillation setup using a pressure cooker? I'd imagine you'd just put a hose running from the valve on the pressure cooker into a cooled vessel like a flask in a cold water bath or ice bath, with an extra hole in it to reduce the pressure.

Thanks for the list!

Not if it makes that clicking arcing sound because that causes a spark which may ignite your hot solvent. You can get hotplates that don't do this but in general its a good idea to do that with ventillation or outside. To steam distill with a pressure cooker you'll need a tube comming off the cooker carrying steam which will go into a glass vessel on a hotplate itself (kept hot) with two holes (steam entry, condensor).

If a liquid is boiled in a flask, always add a piece of unglazed porcelain to the flask bottom. It provides nucleai for bubbles formation that lead to steady, gentle boiling. Otherwise the liquid may become superheated and boil suddenly and violently. Not required if the liquid is stirred. Especially important when a distillation process nears its end.

Use a plexiglas screen when vacuum filtering, or at least wrap all glassware that is under vacuum with a piece of cloth. Glassware may implode if there are cracks. Sometimes they are very difficult to notice.

using a large erlenmeyer on a stirplate, one can do a one-pot extraction while largely eliminating emulsions
by allowing the binary phase system to stir instead of mix.
swim did this with a san pedro extraction of 227g of san pedro powder, and ended up with 1.5g of hcl salts.

THF can usually be substituted for Et2O.

never use rigged setups with organics, especially halogenated hydrocarbons. use all glass.

keep organics stored away from strong acids and bases.

@Trickster: use of antibumping granules is one thing I forgot. Thankyou *edit*

Very helpful thread. Thanks, shoe.

excuse my ignorance, but what is/are antibumping granules?

boiling stones

they can only be used when boiling at atmospheric pressure. they're useless under reduced pressure.

and again, sorry for my ignorance, but what is the benefit of using them?

thanks

The boiling stones provide nucleation sites, which help keep your hot solvent in the flask.

Nucleation sites are .... well... stick your finger in a glass of sprite (or 7up) and you will notice that the CO2 will form bubbles around your finger.. these are nucleation sites. The use of boiling stones/chips allow for a more even distribution of "bubbles" in your boiling solvents. With out them, you can have a large "burp" that will cause your hot solvent to over flow or erupt out of the flask. With them you have a more controlled, even boil.

I know, that was almost incoherent... but if you google nucleation and/or boiling stones you make make more sense of what I've tried to articulate here.

This video will explain it pretty quick: http://www.youtube.com/watch?v=ehbaBiLUCD0

SWIM's got ~4 gig of instructional videos on basic chem teks.

Would it be of any interest to the forum members?

Is it possible to publish them here?

I think such a thing would definitely be of interest to the forum members. Though I don't personally know how you would make them available.

SWIM could of uploaded the files. They are no more than a dozen Meg each.

The forum admin сould relocate them to an appropraiate part of wiki or FAQ.

You could always create a torrent and post it on Pirate Bay. That way it doesn't kill the forum's bandwidth and after you seed for awhile other people will be able to help distribute it.

I've got it from a torrent a while ago. Do not remember from where. Will check if the torrent file is somewhere on my computer.

I thought some of the more actively used teks could be stored here. Most of the files are less than 10 Mb. Torrents die in time.

chem torrents tend to get revised every year. there's one from this year floating around that's 4.3 GB.
the one that was hosted from Synthetikal (2007) is still out there, it's 2.7 GB.

Yeah, I should think they'd be very useful. Send traveler a Private Message. Thankyou Trickster.