UC235 - 2012-10-16
Ethyl acetoacetate is prepared from ethyl acetate by the Claisen condensation. Ethyl acetate containing 2% ethanol is treated with sodium metal, forming sodium ethoxide in-situ. After workup, the product is obtained in 25.5% yield based on ethyl acetate. Considerable ethyl acetate is recovered, but no attempt to recycle and quantify it was made. An error during workup is probably responsible for the reduced yield when compared with the original procedure in Organic Syntheses (www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0235). Calcium chloride is NOT to be used to dry the organic phase prior to distillation, though this is called for in the original procedure. Magnesium sulfate or azeotropic drying is to be preferred. In addition, failure to vacuum fractionate the final product as the original prep calls for means that there are small amounts of contaminants present. As this ethyl acetoacetate is to be used to prepare a fragrance compound, additional purification steps which further reduced the yield were undertaken. The scent of the highly purified product is fruity and rum-like while the product obtained in 25.5% yield had buttery notes (probably acetoin contamination, a side-product) and a hint of acetic acid in addition to this. The intro music clip is from "Stealing Fat" by The Dust Brothers. I believe this falls under fair use.
Great video as always, but I had to poke some fun at how your voice sounds progressively more annoyed as the video goes. There's also a hint of "oh god... what now" Still, you have a level of knowledge and experience I can never hope to equal.
You should do a video on the preparation of Acetylacetone if you still have some sodium \ ethoxide left over, excellent video though :D
Ok, thanks. I might try this synthesis this weekend using citric acid and the neutralization you suggest and I will report back if I can. I like this method of making videos, it shows that science rarely works out perfectly the first time and how to fix it when it goes wrong. Regarding the citric acid, should I just make up a saturated solution and proceed as you describe in the video?
Very interesting synthesis :)
Good to have you back. Great video, as per usual.
Could the extra water at 10:44 be due to calcium chloride simply taking up more volume in solution than it does in its undissolved form?
NICE SYNTH. TOUGH BREAK WITH THAT CACL2 ISSUE..BEEN THERE MYSELF. I LOVE THE CRICKETS BRO, YOU COULDN'T PAY A ZILLION DOLLARS FOR THOSE NIGHT SOUNDS!! NOTHING LIKE LATE NIGHT SYNTHESIS TO SOOTHE THE SOUL.
How long are your shoelaces? What pen do you use to write out a reaction? When you swirl the flask at 6:30, exactly how many revolutions took place? What brand A4 paper?
Ok, thanks. Also, is there a way to purify the product to a higher degree without the use of vacuum distillation?
For neutralizing? I think that you might need the water in there to solvate the resultant sodium acetate and allow phase seperation. I just diluted some GAA.
Tried this out for something to do in my shop. Made a big mess and got a pathetic yield. I recommend if someone needs some ethyl acetoacetate, just buy a bottle. You can get 100mL for less than $20 on eBay including shipping.
He's back!!!
More questions (UC's probably down in the islands (I bet even Cuba he could go to)): Re: desiccants: is the calcium chloride you can buy in a bag to throw on your icy steps anhydrous? And, we can re-cycle desiccants used to absorb water, right? Would sustained exposure to a vacuum coupled with periodic venting with dry air be useful? Or how about heating? Could measuring how cold a sample of water could be boiled be a qualitative measurement of vacuum?
I would base the concentration of citric acid on the solubility of the resulting sodium citrate(s). You might also want to figure out what species will be around at a mildly acidic pH since this is a buffer system and the solubility of those species will be important.
Would lithium ethoxide work in the place of sodium ethoxide? Sorry autocorrect had its way
Good to see you in action again.
Why cannot you upload a video with automatic caption?
that's what's drawn on the paper at the start of the video
1.52 meters (6 feet) Either a Pilot G2 or a Uniball 207 Thirty two and one third. Less if you are only considering the swirling of the contents since they set to a solid paste toward the end. Not a damn clue. They're sheets from a promotional notepad. The back (which I use) is unlined.
I have no idea....I assume that all my bottles are just soda-lime glass, though some may be borosilicate. You're overthinking this. I bought most of them from an army surplus guy in bulk. I have small bottles with polypropylene cones and others with teflon or silicone liners. The nitric acid bottle is just brown glass. The caps on those bottles are just laminated paper with some sort of plastic coat on the exposed part. I added a disc of teflon sheet that I cut out to that one.
Get an oil bath.
How nice of you to answer those silly questions. I better make up for it with a real question... Probably just as pointless a question as the last 10 asked of you, but those three neck flasks, hypothetically if you only needed two of three necks in the reaction and you stoppered the third neck, could the built up pressure shoot that motherfucker across the room? Just to clarify, I'm not in this dilemma, just curious if anyone's ever done it.
Yeah, I stopper off extra necks all the time. As long as the apparatus is not a closed system (or something catastrophic happens) the pressure will just equalize itself through the available pathways and the stoppered neck might as well not exist.
Would Lithuania
I'm not sure if ethyl acetoacetate decomposes if you try to distill at atmospheric pressure. You could wash the organic residue with NaHCO3 solution after pulling off the ethyl acetate and distilling that would probably give a cleaner product in the first place along with a higher yield than a 2-step cleanup. Hindsight is always 20/20. I rarely do trial runs for videos and I try to troubleshoot as things happen.
I would not use vinegar. Ethyl acetate and ethyl acetoacetate have significant water solubility. The concentrated sodium acetate solution resulting from neutralizing with 50% acetic acid probably goes a long way to keep these in the organic phase. Much more dilute acetic acid would dissolve a lot more of both and give even poorer yield, which is already fairly low. What you might be able to do is use a solution of citric acid or another organic acid whose sodium salt has fairly high solubility.
My thoughts are.. I like the video but I can't read the descriptions in the video mabye a larger font.. fat osl3
english?
Who else think he makes meth in his free time
Joe Anderson - Wales, UK - 2012-10-16
Glad to have you back - a very interesting synthesis, thanks. How important is the concentration of the acetic acid used after reflux, i.e. could vinegar be used?