Dec 26, 2009

Season greetings from RBF

Merry Christmas!

Hope you guys had a great christmas. Personally I had one of the better ones this year, and a contributing factor was some pretty neat gifts (which are chemistry related).

First up, my gorgeous girlfriend gave me a copy of Julia Child's 'Mastering the art of French cooking'. As Child explains herself in the introduction, this is not merely a cookbook but a textbook on how to cook. What I like about it is Child's philosophy which comes out through her book: that cooking is an science as well as an art, in that it should be reproducible given the right technique is used, a philosophy that I can appreciate as an organic chemist. (This is compared to Jamie Oliver's 'just bang it in the pot' sort of style. This probably reflects my chemistry style: I like things to be done 'properly', rather than being a maverick). You might be wondering why I'm talking about cooking in a chemistry blog, but as we all know, all good chemists are good cooks (not trying to imply that I'm either the former or the latter!), so there's the link.

My second chemistry related christmas gift is this truly stylish shirt from the folks at

This one is from my brother, worn today with pride at the Boxing day sales. If you haven't already, check out some of the other stuff they sell at webelements. Some of the stuff is truly inspired COOLNESS, but probably still not as cool as the Corey mug.

Anyway that's all from me. Enjoy the rest of the festive season and a HAPPY NEW YEAR to you all from the guys at RBF!

Dec 18, 2009

Hmmmm tasty water...

Came across this on Google Reader this morning:

Reminds me of that time I used triphenylarsine... I had a organostannane and HMPA in that same reaction.

Dec 11, 2009

What the hell does this do?

I was rummaging through the many drawers of glassware I have, and I found this broken piece of glassware:

What the hell is it used for? Electrolysis? Ozone production?

Dec 10, 2009

When people pretend they know chemistry

With the boxing day sales coming up, I thought I'd look into buying some cookware. Labchimp suggested a few pieces of essentials for me, such as the Scanpan classic frypan, but he also suggested that I take a look at the Swiss Diamond fry pan, which as the name suggests contains diamond on the cooking surface. Apparently it's supposed to conduct heat better than copper and is nonstick (not to mention very very hard).

I thought I'd google any reviews on these fry pans, and I came across this forum thread. As with a lot of threads, things get off topic, and eventually these guys are engaging in a war of words, each armed with their own arsenal of pseudoscientific jargon and arguments. Fascinated and disgusted, I kept reading, and this post by glenngarden is by far the most ludicrous:

AkChicago, the temperature rating of the Eurolux says it all. It is heat resistant to 1200 deg. C. and the surface is ten times stronger than steel. PTFE breaks down at 500 deg. F. You certainly know the conversion of Fahrenheit to Celcius. C = 5/9 x(F-32). So 500F = 260C. And really we know that PTFE starts to kill birds at much lower temperatures.

So Eurolux cookware surface is rated for 1200 Deg. C.
ScanPan pan surface is rated for 260 Deg. C at best. Higher than that it certainly kills the birds. If it kills the birds do you want to use it?

As you correctly point out, PTFE is a Flourocarbon: Poly Tetra Flouro Ethylene. Notice the Flourine molecule that's in PTFE. Eurolux doesn't use Flourine molecules. Hey, I think Flourine gas is a quick killer, too. And you should not drink Flouride water or use flouride containing toothpaste either. Flourides are known to cause cancer, too. If you want to find Flouride free toothpaste, just visit your neighborhood healthfood store, Whole Foods, etc.

Carbon is an element, no 12 on the Periodic table. Humans are made from carbon compounds. Diamonds are made from pure carbon depending on the crystal structure. Diamonds are the hardest substance and have the highest melting temperature. Nothing unhealthy about carbon. Lead is also made of carbon, and it's not healthy. But the temperature rating of the Eurolux tells you that the carbon fibers are not lead! However, many carbon containing polymeric compounds are deadly. PTFE/Teflon is known to cause cancer in rodents. Carbon doesn't cause cancer. We are made of carbon. Carbon is healthy. PTFE is a carcinogen. Eurolux is heat resistant to 1200 Deg. C. Scanpan fumes at around 200 deg. C, well below frying temperatures.

If you want to eat healthy, or remove at least one source of carcinogen in your life, stay far away from any PTFE pot or pan. Stay away from ScanPan carcinogenic PTFE pots and pans. Use something healthier.

If you don't want to spend the money (Eurolux is expensive), then use high quality stainless steel. Stainless steel is a healthy cooking surface, non carcinogenic, but the eggs won't slip off the pan. You will have to scrub for 10 minutes. But I'd rather scrub for ten minutes, get some exercise in the process, than get cancer with ScanPan. Wouldn't you?

Where do I start with the problems in that... that PTFE doesn't have any fluorine molecules? Eurolux uses a different type of fluorocarbon as their nonstick agent, but somehow that doesn't possess any 'fluorine molecules'? What does PTFE have to do with fluorine gas? and What does fluorine gas have to do with fluoride toothpaste? I mean, maybe we should stop eating salt because chlorine gas is toxic and sodium reacts violent with water!!!

Humans are made from carbon compounds, ok fine, but I can name in my sleep about fifty carbon compounds that will kill you. Sure carbon is not unhealthy anymore? How does diamond's hardness and melting temperature have anything to do with whether PTFE is toxic? Since when did we learn how to make lead from carbon? But if there's nothing unhealthy about carbon, then why is lead which is supposedly made of carbon unhealthy? The temperature rating of Eurolux tells you that the carbon fibres are not lead? HHHHHHHWAAAT?????

Wow wow wee, carbon doesn't cause cancer... I wish you told me that during that time in the lab when I had to catalogue every chemical in the lab and found that the HMPA bottle's lid was completely cracked. Oh by the way the other element found in PTFE is CARBON.

I'm not too worried about whether the PFTE is going to kill me or not. If you're going to use a nonstick pan, don't expect to use it on high heat. Keep it on medium or low and you'll be fine. For high heat go for a solid metal pan with no organic coating. In any case, how much more toxic things than PFTE have us chemists been exposed to anyway. Bring on the nonstick!

Dec 2, 2009

I hope everyone is setting up their Christmas tree

So I helped my fiancee's mum set up her Christmas tree last night. Mainly because she is short and I am not. I got the honour of putting up the star. Meanwhile, my finacee sat on the couch and wanted nothing to do with the tree. Great holiday spirit there. IMHO it is a nice tradition but I guess some things come and go like that.

All I really want to know is how many people set their tree up on the 1st of Dec.? and how many leave it till someone else reminds them that they should have set it up then?

I would also just like to wish all our students, who we do verbally bash quite a lot, a very happy holiday season and to let them know that the guys at RBF are hoping they did well on the exams. Hope to see you all next semester for some more Org. Chem. YAY! and also ask why the F&@* aren't you in a lab doing some summer work over the holiday period?

Oh I also thought that seeing as though it was thanksgiving not so long ago I would thank all the biologists and engineers out there for giving us fodder to slander you profusely both openly and behind your backs. Now biologists get back to your coffees and engie's get back to the pub you lazy S.O.B's.

RBF Teaches: How to perform an extraction

Ok kiddies,

While it might seem simple and easy, I can tell you now, a lot of you are doing it WRONG! The seperatory funnel is an integral part of the organic and though I hate to say *GUH*. The principle is pretty straight forward - desired product + byproducts go in, desired product comes out pretty clean and dry and ready for analysis.

The general method is to use some sort of aqueous phase, usually used at the end of your reaction to "quench" (neutralise the reagents) and a polar solvent of some sort to draw out your desired compound. The aqueous "phase" or layer can often have some sort of salt dissolved in it (NaCl is common, as is NH4Cl) this is to saturate the water layer with salt so that the organic compounds dissolved in it are more readily taken up by the organic solvent phase as they are less soluble in the aqueous phase due to the salts.

The organic solvent that you add is really quite dependendant on the product you are making, for example some polar compounds can only be drawn out with a very polar solvent like Ethyl Acetate (EtOAc) or Chloroform (CHCl3). The one thing about the organic solvent is that it MUST NOT BE MISCIBLE with water i.e. does not dissolve in water. This can be gauged by the density of the solvent if the solvent is  significantly more dense (density >1) then the solvent will sit below the water layer. Conversely, if the solvent is less dense (density<1) then the solvent will sit above the water layer. Usually, lighter solvents are chosen as they tend to be cheaper than the more dense.

Ok, so here is the IMPORTANT part.
  1. Make sure the tap is closed and clamp the sep. funnel by the NECK (i.e. the small region where the stopper inserts) don't clamp it anywhere else, it will break. 
  2. Wash your sample into the sep. funnel (usually use both a small amount of the aqueous and the organic solvents AND FOR THE SAKE OF ALL THINGS GOOD AND HOLY USE A FUNNEL). 
  3. Put a stopper on the top of the sep. funnel and place your index finger over the stopper and hold the flask with your dominant hand. Unclamp the sep. funnel and with your index finger still in place invert the funnel. 
  4. Shake the funnel to mix the solvents, don't be a baby about it but don't go overboard - shake too vigourously and you will most likely end up with an emulsion of layers that will take quite a while to seperate. Every 5 shakes or so it is a good idea to point the inverted sep. funnel into the fume hood and open the tap to release the vapour pressure that has undoubtedly formed. 
  5. Once, you feel you have shaken enough, usually after about 20sec you can clamp the flask by the neck again BUT MAKE SURE THE TAP IS CLOSED. 
  6. Then REMOVE THE STOPPER - if you don't the sep. funnel will not pour. 
  7. Allow the layers to seperate nicely and then begin draining the lower layer. As a general rule I usually say "if you want the top layer leave a bit of the bottom layer in the funnel, if you want the bottom layer take a bit of the top through as well". While I know it isn't exactly necessary you often find that that way you don't really start worrying about getting the seperation exact. 
  8. If you were after the top layer then collect this in a different collection flask. Make sure the collection flask is quite a bit larger than the amount of solvent you intend to collect.
  9. Pour the AQUEOUS layer back into the seperatory funnel (needless to say, if your aqueous layer was the top layer you don't have to drain this first then pour it back in).
  10. Add again the same amount of organic solvent as in step 2 and repeat the steps 3-9. Do this twice so you have 3 extractions overall. 
  11. It is a good idea to TLC your extracts to make sure you are taking the desired spots through and when they have stopped coming through. A good way to do this is to take a TLC spot from a drop of organic solvent on the tip of the sep. funnel.
  12. OPTIONAL - sometimes unwanted material may also come through with the organic solvent, in this case a wash of the organic solvent with clean brine or water may remove these impurities. This simply requires you pouring the organic solvent into the emptied sep. funnel and adding the aqueous wash. (PLEASE USE A FUNNEL)
  13. Once you have collected all of your organic solvent you can add a drying agent to remove any water that may have inadvertantly come through. Usually, sodium or magnesium sulfate works a treat. Simply take your collection flask, which should only be 1/3 full or thereabouts and gently swirl the solution while sprinkling in the drying agent. Swirl the flask for about 1-2min to ensure the water is absorbed by the drying agent. You should see clumping of the drying agent that indicates water is being taken up but once the drying agent stops clumping you should have a dry solution.
  14. Filter off the drying agent and make sure to wash the filter with more of your organic solvent to ensure all of the extracted compound is taken through. Usually you would filter into a PREWEIGHED round bottom flask of sufficient volume (twice as large RBF as the volume you have) and then place the RBF onto the rotavap to remove the solvent.
  15. Pump the resultant product down and Bob's your uncle. You may have to run a column on your product after this but any tricky ionic/salt compounds will be removed and you will have at least a crude weight and something to analyse by NMR or GCMS.
Important points to remember
  • Make sure the tap is closed before you add your solution or turn the sep. funnel upright.
  • Use a damn funnel for pouring solvents.
  • Hold the sep. funnel stopper with your index finger before you unclamp invert it.
  • The sep. funnel should be inverted the entire time it is in your hands.
  • Don't shake too hard or you will get an emulsion. 
  • Remember to release the vapour pressure. 
  • Make sure the tap is closed before you turn the sep. funnel upright.
  • Remove the stopper once you have your sep. funnel clamped.
  • Don't add too much drying agent. It is a waste.
  • Pre-weigh your RBF!