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Sigmatropic
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[*] posted on 30-6-2018 at 10:36


When finishing a liquid-liquid Iextraction gently swirl the sep. funnel to knock down last droplets from the walls.

When encountering emulsions gently heat the emulsion from the outside of the sep. funnel with a heat gun. The increased temperature increases the molecular movements causing the emulsion to break up faster. (note that occasionally cooling is beneficial as some but not all solvents become (more) immiscible below a certain point, see for instance the bahavior of MeCN-H2O. Sometimes solvents become less miscible by increasing the temperature (as is described in Vogel's). I do not know how ternary systems behave but I had the feeling that the DCM-MeCN-H2O system gave better and faster separations at or below 0C.

And finally for those ocd on purity, use the stopcock of a sep funnel to capture the thin film present at the interface and remember to remove the bottom layer through the bottom and the top layer through the top (after you've drained the bottom layer obviously).
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[*] posted on 14-9-2018 at 08:21


I often use a reflux condenser above the distillation receiver, especially when distilling volatile chemicals. Like this: http://www.prepchem.com/synthesis-of-p-toluquinone/

I think this is fairly common.

[Edited on 14-9-2018 by JJay]




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[*] posted on 14-9-2018 at 14:44


Eyewash: it doesn't have to be a professional eye wash.
A squeeze bottle of saline from the contact lens section of your local store works wonders. But always have something to use as an eyewash, even if it is just a bottle of water.

O-rings for thermometer adapters: Automotive O-rings that are suitable for E-85 and regular gas are made of viton. This is compatible with most things except ketones, and even then they are cheap to replace, most automotive stores carry a variety. You can get teflon o-rings as well, they are literally more expensive to ship than buy (US$ 1.30 for 5). A ground glass thermometer well never has o-ring problems and you can use regular cooking oil as a heat transfer solution without worrying about contamination.

A better option for the use of teflon is to wrap the thermometer below the adapter and then pull it up to seal it and protect your 25 cent o-ring.

Lab apparel: Jeans and a long sleeve shirt are a minimum. Protect your arms. Wear boots not cheap shoes. Pretend like you are cooking and moving around hot oil. A lot of lab chemicals aren't nearly as bad as hot oil but working like it is will save a lot of trouble later.

Fires: If you have a fire, you did something wrong. BUT, you should have appropriate materials to put out the fire you are working with. Baking soda works better than water on most organics as it releases CO2 and doesn't spread the fire. Oil or sand work better on metal fires than water. But you may need to extinguish the oil after you put out the metal.
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[*] posted on 14-9-2018 at 17:15


Quote: Originally posted by VSEPR_VOID  
Quote: Originally posted by crystal grower  
I started using lab coat after destroying sufficient amount of T-shirts :P.


Same...I am up two two shirts and a pair of pants.


Same here :'D Lab coat is not a piece of clothing, rather a line of defense, something to quickly remove and throw away when compromised with some nasty chemical.

The material (cotton) is especially good in absorbing stuff.
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[*] posted on 14-9-2018 at 17:32


Improved thermometer.

It's simply the TM-902C probe inside a thermometer adapter filled on bottom with thermal conductive paste and some glass wool and duct tapes to keep it all in place. This improves response and accuracy of the readings.

Credit goes to ChemX YouTube channel.

thermometer.jpg - 202kB
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[*] posted on 15-9-2018 at 01:11


i did a similiar thing some time ago when i broke my only mercury thermometer, i used a pipette, melted the tip and inserted the K-therocouple to its bottom, the glass there is thin so the heat capacity is small, the temperature reading is really fast upon changes in temperature. i think that with all that conductive paste you have quite some heat capacity, less is better to get a fast response

20180915_105626.jpg - 494kB 20180915_105744.jpg - 685kB





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[*] posted on 15-9-2018 at 07:38


Quote: Originally posted by Ubya  
i did a similiar thing some time ago when i broke my only mercury thermometer, i used a pipette, melted the tip and inserted the K-therocouple to its bottom, the glass there is thin so the heat capacity is small, the temperature reading is really fast upon changes in temperature. i think that with all that conductive paste you have quite some heat capacity, less is better to get a fast response


Good idea thanks. I have lots of pasteur pipettes but unfortunately no way to melt them. I guess a butane torch lighter wont be hot enough right?

I needed an adapter instead of rubber stopper because sometimes I distill aggressive stuff and the rubber would degrade. But I guess something similar can be done with an air inlet tube.
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[*] posted on 15-9-2018 at 07:46


One more tip is to have certain common chemicals in a freezer, especially brine, sulfuric acid and solvents like acetone.

Brine can be used to chill a solution below 0 °C, it's more effective than an ice bath and is always liquid so easy to recycle/reuse.

Pre-chilled sulfuric acid is practical for dilution - in most cases adding it to a reaction mixture is highly exothermic so the pre-chilling helps a lot.

Chilled solvent (e.g. ammonia solution, acetone, ethanol etc.) is practical for washing products.

It also comes in handy to have distilled water frozen in ice cubes (amount can be weighed). This way you can pour hot stuff on it or quench a reaction without having to set up an ice bath beforehand.

I have a portable 30L car fridge/freezer for lab use. It has a compressor and thermostat so you can even set temperature down to -20 °C.

...or and a microwave is probably the fastest way to heat up water. It saves lot of time.

[Edited on 15-9-2018 by nimgoldman]
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[*] posted on 19-2-2019 at 23:16


Use a glass stir rod to help pour liquids. Keep several scupulas on hand and have one specifically set aside for heating substances.

Check thrift stores for cheap equipment like compressors, pumps, glass containers, fridges, power supplies, heating elements, and even depression glass.

Keep a UV light in your car for finding interesting minerals or depression glass.

Do reactions on a bulk scale if you are going to be using the product often. This includes making nitric acid, diethyl ether, or dry solvents. This boosts yield as you lose less to mechanical losses.

Make stock 1 M solutions of test solutions and titrations and keep them in bottles with droppers. Its also very ascetically pleasing.

You can cut old aerosol cans and propane tanks open to use as reaction vessels or chambers.




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[*] posted on 20-2-2019 at 15:34


Quote: Originally posted by nimgoldman  
Quote: Originally posted by Ubya  
i did a similiar thing some time ago when i broke my only mercury thermometer, i used a pipette, melted the tip and inserted the K-therocouple to its bottom, the glass there is thin so the heat capacity is small, the temperature reading is really fast upon changes in temperature. i think that with all that conductive paste you have quite some heat capacity, less is better to get a fast response


Good idea thanks. I have lots of pasteur pipettes but unfortunately no way to melt them. I guess a butane torch lighter wont be hot enough right?

I needed an adapter instead of rubber stopper because sometimes I distill aggressive stuff and the rubber would degrade. But I guess something similar can be done with an air inlet tube.


I just melted a Pasteur pipette over the gas burner on my stove, so I'm pretty sure almost any torch would do the trick.

I haven't had any luck melting PYREX that way though, but Pasteur pipettes are soda glass I think. (Sure does melt like it.)




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[*] posted on 20-2-2019 at 19:27


Cut some thick rubber tubing to cushion iron rings that hold sep funnels. You don't want a funnel breaking when full of fluids.

It always makes my teeth stand on edge when I see glass-on-iron in chem videos.




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[*] posted on 20-2-2019 at 19:29


Use sealed off pipettes or small test tubes to make ampoules to hold volatile or air/moisture sensitive compounds. Much cheaper than buying ampoules, too.



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[*] posted on 21-2-2019 at 11:04


Quote: Originally posted by SWIM  

I just melted a Pasteur pipette over the gas burner on my stove, so I'm pretty sure almost any torch would do the trick.

I haven't had any luck melting PYREX that way though, but Pasteur pipettes are soda glass I think. (Sure does melt like it.)


I seal Pyrex and Kimble capillary tube tips with a stove flame. And on boro Pasteur pipettes you can seal both sides with this sort of flame (you will need to thoroughly pre-heat your crimping tool for the broad side though).

Boro Pasteur pipettes can be sealed at the tip with a bic lighter, even!


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[*] posted on 21-2-2019 at 17:16


Quote: Originally posted by happyfooddance  
Quote: Originally posted by SWIM  

I just melted a Pasteur pipette over the gas burner on my stove, so I'm pretty sure almost any torch would do the trick.

I haven't had any luck melting PYREX that way though, but Pasteur pipettes are soda glass I think. (Sure does melt like it.)


I seal Pyrex and Kimble capillary tube tips with a stove flame. And on boro Pasteur pipettes you can seal both sides with this sort of flame (you will need to thoroughly pre-heat your crimping tool for the broad side though).

Boro Pasteur pipettes can be sealed at the tip with a bic lighter, even!




I have done some of the capillary tubes with a bic for shits and giggles but have never tried a boro glass. Interesting info :)
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[*] posted on 21-2-2019 at 17:50


the rubber "bumpers" on the magnet off old subwoofers make excellent RBF holders




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[*] posted on 21-2-2019 at 19:26


Quote: Originally posted by arkoma  
the rubber "bumpers" on the magnet off old subwoofers make excellent RBF holders


I doubt many people are going to have that available but it would probably work well.
I'd bet most people have some old garden hose, vinyl tubing or even old inner-tube (car, tractor, bike, etc). I'd think that all of those would work well. Failing that, I don't see why you couldn't use paper towels (fold it over a few times and put it between the glass and metal.
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[*] posted on 22-2-2019 at 18:44



Pulloff the back of an old subwoofer, nice and "grippy" from being rubber


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biggrin.gif posted on 23-2-2019 at 08:57
That's One Less!!


Nice work! That is one less of those annoying
speakers that always go BOOM BOOM BOOM in the night
as some dweeb drives around in his ghetto blaster!:cool:




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[*] posted on 24-2-2019 at 11:56


Quote: Originally posted by morganbw  
Quote: Originally posted by happyfooddance  
Quote: Originally posted by SWIM  

I just melted a Pasteur pipette over the gas burner on my stove, so I'm pretty sure almost any torch would do the trick.

I haven't had any luck melting PYREX that way though, but Pasteur pipettes are soda glass I think. (Sure does melt like it.)


I seal Pyrex and Kimble capillary tube tips with a stove flame. And on boro Pasteur pipettes you can seal both sides with this sort of flame (you will need to thoroughly pre-heat your crimping tool for the broad side though).

Boro Pasteur pipettes can be sealed at the tip with a bic lighter, even!




I have done some of the capillary tubes with a bic for shits and giggles but have never tried a boro glass. Interesting info :)


I have checked my big box'O Pasteur pipettes, and they are in fact boro, as happyfoodance's are.
I just assumed they weren't because they melt really, really easily.
Must just be the thinness and fine point that makes em melt so nice.




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[*] posted on 2-3-2019 at 16:43


Wear safety glasses fucking always, have a fire extinguiser on hand of the correct type, use boiling chips and never take your eyes off a distillation, or at least keep an eye on it



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