Boron Meltdown
February 9th, 2009 by excimerI need to start watching Conan again.
As someone who deals with boron compounds every day, Conan, let me say thank you. Those assholes at the NY Times wouldn’t know element number 5 from a hole in the ground.
Conan needs to bring back Celebrity… [Secrets]. Imagine if they had Chemistry Celebrity Secrets. Aside from being boring, it might actually be funny.
OMG!!!! That was awesome!!!!! I’m going to start watching again.
Not only did I invent every palladium reaction ever made, but I also invented palladium in ‘65. There was a big hole in the periodic table above platinum before I started chemistry, and I fixed it.
I only report GC yields because GC actually stands for “Good in theory/Crap in reality” in our papers. We make the numbers up. What’d you THINK it stood for? Gas chromatography?
Fantastic video!
Thanks for posting.
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Fucking god damn it. This is what you get for living in the south pacific ocean.
Yes, I so pity the people who live in the South Pacific right now.
…
Well we’ve got it so sweet here in NZ we have to find SOMETHING to bitch about
Same thing in Mexico. I guess I’ll have to wait until I get home to view it.
National War on Boron. Homeland Severity warrantlessly searches for, seizes, and destroys all boron to Save Our Children! Herbert C. Brown gets resurrected then waterboarded. Rinse, repeat. What’s the problem?
Aren’t lots of boranes pyrophoric? Karma could be a problem for the waterboarders. I don’t consider that a problem, exactly, but there’s no rinse and repeat cycle there.
what’s your beef with negishi?
you dimwitted newb
Hello Purdue chemist! I, personally, have nothing against Negishi. He’s about a 95%1 great chemist.
1 Yields determined by GC
It’s funny how palladium chemistry review articles etc written by Negishi make a great point about the superiority of Negishi coupling compared with Sonogashira, particularly when it comes to yields. It must piss him off that the more popular alkyne coupling doesn’t bear his name. Also his alkyne coupling with ZnBr2 and tertiary amine (which btw didn’t give a clear solution like they were supposed to) never gave me the results they touted. Then again it was with Pd(PPh3)2Cl2. Maybe Pd(PPh3)4 would have worked, never tried.
Any catalyst BUT PdCl2(PPh3)2 works great, especially if you use a hot ligand like PtBu3 or a Buchwald ligand with a good Pd(0) source (most commonly used is allylpalladium chloride dimer-Pd2dba3 doesn’t work as well). I do this coupling via “soft” deprotonation with ZnBr2/NEt3 all the time and I get quantitative yields (nearly) every time. It doesn’t work with Pd(II) sources cause there’s no way to get down to Pd(0) when you use zinc halides (zinc acetylides don’t homocouple).
It is my experience that Sonogashira with aryl brodies using Pd(II) does not start until you throw in Cu(I) salt. The right procedure is to mix PdCl2(dppf) 3 mol% with ArBr and 1-alkyne 1.2 eq and NEt3 1.5 eq in fresh THF, Ar sparge on ultrasound for few minutes and THEN throw in CuI or CuBr 1.5 mol% solid and cap the vial. The color promptly changes from red to gray to gold yellow within minutes at room temp, later NEt3.HBr begins to precipitate out. but the color stays yellow until the quench. I think Cu-acetylide is the actual Pd-reducing agent. NEt3 can also reduce Pd(II) but you need reflux temperature and long reaction time – and your alkyne is likely to perish by the Pd(II) long before it gets a chance for a sonofashira
So the issue was the one I suspected. I shall keep this info in mind, thank you very much.
Wow, this made my day. He’s amazing…
Phil Baran is my son! Yes, a great shock! You didn’t see that one coming, did you?
…you did? Oh. Never mind.