NH3 and pour it directly liquid from a baby-sized tank into a wide-mouth Erlenmeyer, then throw some Na until the stuff is blue, no moisture exclusion, no cooling (ammonia high heat of vaporisation takes care of that). The major barrier on plant is cooling, -50°C is a challenge for most chillers in the lab but at scale its unachievable.
Were you trying to purify the ammonia by condensing it on a cold-finger? This new paper (from a group at China Agricultural University) describes an ammonia-free (and indeed, amine-free) variant of the reaction – you use commercial sodium dispersion with a crown ether in isopropanol, and you can do it all at zero degrees C, as opposed to the -30 or so you have (at most) in liquid ammonia. I have used the Na/silica for a diester coupling and it works very well, but so does Na/xylene if you can get the Na to stay as fine particles (once shook a few hundred grams of Na in 120C xylene by hand….. That was pre-health and safety). They’re looking at this system to replace the more toxic/less sustainable systems for using solvated electrons as reducing agents.
I have a respirator which is rated for ammonia that I purchased online in preparation for this reaction. I thought the trialkyl substituted electron rich benzene in the substrate was to blame for the slow rate but now I realize maybe I used too pure lithium metal. In this case, the reaction is done fairly concentrated (more so than the ammonia ones), and the authors just do an ether/brine extraction without evaporating the isopropanol away. I did my first Birch under the tutelage of a fantastic post-doc who called it The Ty-D-Bol Reaction; since then, so do I. I never thought about that ! Thank you for that answer. We regularly see blue solvated electrons in synchrotron experiments. I once worked on Birch reduction of dehydroabietane skeleton with Li/tBuOH/THF in refluxing liquid ammonia – it worked but it was painfully slow (36 hours to completion, even with huge excess of Li that formed liquid shiny Li bronze solution at the high concentration at the top layer, separating from the less Li rich deep blue layer bellow. The reaction is named after the Australian chemist Arthur Birch. . Bouveault Blanc reduction (sodium metal, liquid ammonia, ethanol) is pretty damned green chemistry. A word of caution: pure ammonia, in either its gaseous or liquified form is extremely dangerous to handle, especially in the context of your 'hobby' where, in your own words you "don't have access to a ton of glassware or specialty equipment."
What does it mean when something is said to be "owned by taxpayers"? I used the cold finger to condense bromotrifluoroethylene, chlorotrifluoroethylene and 1,1,2,3,3,3-hexafluoropropene. Birch Reduction Reaction is an organic reaction which is used to produce cyclohexadienes from aromatic compounds. Chemical & Engineering News will not share your email address with any other person or company. The only way is liquid nitrogen, which is more expensive that you might think and also sends most chemical engineers into meltdown.
A novel protocol for a significantly improved, practical, and chemoselective ammonia-free Birch reduction mediated by bench-stable sodium dispersions and recoverable 15-crown-5 ether is reported. And condensing ammonia always seems like a magic trick, as the clear liquid just appears on the dry ice cold finger and drips down into the flask.
That is just freaking misleading lies. All content is Derek’s own, and he does not in any way speak for his employer. In graduate school, I had a dissolving metal reduction as an early step in a pretty long sequence. Exactly – it’s more trouble than it’s worth, in reactivity, waste disposal, etc. That said, it would require an argon line and I wouldn't do it without a fume hood. (optional). Perhaps that does not sound as bad as HCN until you look up the toxicity, about 1000x HCN and the same mechanism. Lower molecular weight alkyl amines can be used in place of anhydrous ammonia for a birch reduction, if your just wanting to observe the blue colour this might be a more practicle alternative. Rather, please cite leading literature that might help illuminate the situation. It cools down methanol to -90 °C with liquid nitrogen. http://pubs.rsc.org/en/Content/ArticleLanding/2017/SC/c7sc03514d#!divAbstract is the abstrtact for the actual paper, “Laboratory-scale photoredox catalysis using hydrated electrons sustainably generated with a single green laser” Robert Naumann, Christoph Kerziga and Martin Goez*. Another advantage to the Birch is that you typically just let the reaction warm up to get rid of all the ammonia, letting you switch to whatever solvent system you want for the workup. Then went back to the rotovap, took my flask off, and very carefully washed the whole thing down with acetic acid solution… Never again, thanks, but now at least I know what diazomethane smells like….
That prep starts out just like a Birch, but the iron sends it down a different path. Anyway, I now make it with a fast overhead in xylene at 120C. A colleague knew the sales person who wanted to get the market going and he offered us a kilo for a very low price, but the shipping to the UK was painfully expensive so we just bought a small amount to try. It looks like this reaction does pretty much what the classic Birch does. I'm quite curious. A cold finger with dry ice/acetone is sufficient to cause the ammonia to condense into the reaction flask.
Hopefully you can write about that in more depth soon? Discount will be applied automatically at checkout. Lithium amide on the other hand is somewhat more expensive but perhaps more importantly seems to age on standing – no matter how carefully you store it. Do you need a trace of Li when you do a Na Birch? Toxicity of H2S is roughly on the same level as HCN. Used the ester after that. And of all the gases that I’ve seen condensed on a cold finger, ammonia is definitely the one that I’d rather work with (as opposed to liquified HCN, for example, which I’ve seen once and have no desire to encounter again). The reaction they detail takes place at 0 deg C and produces reduced phenanthrene at 60% yield. Also your picture of the dissolved reducing metal/ ammonia solution shows a solution with a ton of free e-; it seems almost black instead of blue. Can a Birch Reduction be done using gaseous anhydrous ammonia?
H2S poisoning is reversible with fresh air and resuscitation whereas HCN poisoning needs a rapid administration of nitrite+thiosulfate antidote, and the recovery is quite problematic, By the way, the safe way to test whether you can smell cyanide (some people can’t) is to take off a cap from bottle of solid, and carefully sniff at the cap liner (not the bottle content!). Our problem was that it always assayed as being fine even when it looked and smelt wrong (it seemed to give off ammonia, which has low odor threshold – we weren’t intentionally working by ‘sniff-test’).
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The products, however, may be unexpected. Determining CRS from given point coordinate set. The order of binding placed H2S as much tighter than CN. Not having to break out the ammonia tank does sort of lower the barrier to running the reaction, it’s true, although I always regarded that as a sign that one was about to do some serious Birching.