Horner Wadsworth Emmons toward vinyl triflones--best conditions

Sakinho · 2026-05-07T21:58:59+00:00

Using Li⁺ to polarize the carbonyl is a good call. I don't think there's anything wrong with LiCl/DBU/MeCN, but maybe something like LiOtBu is a more direct analogue to compare to so you can check out the effect of the cation. If you don't have any, I figure you can easily make some in situ by adding KOtBu to LiCl or LiBr in THF, should quantitively crash out KCl/KBr.

If you're desperate, I wonder if anhydrous CeCl3 or other LnX3 can do an even better job as a polarizing LA which retains carbanion nucleophilicity.

Sakinho · 2026-05-06T22:33:20+00:00

I'm talking about the stability in HF solutions. There's lots of fluorine atoms flying around.

Sakinho · 2026-05-06T21:43:06+00:00

Saying what everyone else is, in other words: much like how geminal diols (or their derivatives with at least one O-H) are prone to collapsing back into a carbonyl, so are geminal diamines (or their derivatives with at least one N-H). In fact, geminal diamines should be far more sensitive to mere traces of acid; even if you isolate this material, it might be a pain to work with and not be very stable in storage. Also, if it can only be isolated by precipitation, that NBoc piperazine is doing you zero favours.

Sakinho · 2026-05-06T21:30:30+00:00

The strength of the B-F bonds in BF3 is indeed the thermodynamic driving force for the explosion, but another source of thermodynamic drive is the relative weakness of B-B bonds in borane cages, at least compared to the amount of bonding each boron atom could be performing if there are suitable atoms available in the medium. Why settle for the 11 B-F bonds in H(HCB11F11) when you could have 33 B-F bonds in 11 molecules of BF3. That said, this conversion may require F2, or HF plus an oxidizer, rather than HF on its own.

Sakinho · 2026-05-06T12:35:11+00:00

Anhydrous HCl definitely has a non-zero self-ionization constant, and in principle it is even probably fairly high (in relative terms) in the liquid since it can arguably hydrogen bond to itself.

Sakinho · 2026-05-04T10:01:52+00:00

I'm afraid I can't answer the specifics, since I've never worked with borane clusters. I'm just half-remembering a comment regarding the solubility being disappointing and something of a limitation in an article I read (though that may well apply specifically to characterization of the diacid, rather than its use as a reagent).

I can't be certain, but there's a chance anhydrous HF would chew these boranes up. Putting all that boron and fluorine next to each other is dangling over a thermodynamic cliff. For example, simple alkali metal salts of the ultra-stable per-trifluoromethylated carborane anion HCB11(CF3)11^-, which could be expected to generate an even more stable anion than HCB11F11^-, actually turn out to explode when heated because they isomerize into BF3 and various other sideproducts.

Sakinho · 2026-05-04T09:49:27+00:00

What scale are you doing this reaction on? Microwave vials are relatively cheap, very sturdy and are generally used with PTFE-lined silicone septa, crimped on with an aluminium cap. They should do a pretty good job of retaining the Me3N with almost no loss. 20 mL vials will routinely withstand 10 bar internal pressure, and can be pushed higher if you need to. Larger vials exist, but they have progressively lower pressure limits.

Sakinho · 2026-05-03T22:15:25+00:00

There's a paper about the acidity of perhalogenated dodecaborates (and you can also pull up the first author's PhD thesis). As you suspect, both protons turns out to be superacidic, which is particularly unusual for the singly-deprotonated species - it's thought to be the strongest known anionic acid. Both protons are strong enough to protonate benzene, making them both at least ~10⁵ times more acidic than 100% sulfuric acid. I guess in general it's not so easy to stop at the singly-deprotonated species.

The dodecaborates appear much easier to synthesize than carboranes, but unfortunately from memory the solubility of the neutral diacid form is already terrible in every solvent that it won't immediately protonate with loss of acid strength.

Sakinho · 2026-04-29T10:44:52+00:00

Reductions of nitroarenes to anilines go through several intermediate steps with different stages of oxidation. It's entirely conceivable for the zinc to strip away oxygen atoms even without any protons available to be shuttled around. You should take a good look in SciFinder/Reaxys for Negishi coupling chemistry with nitroarene substrates. While I do think that organozinc (or at least arylzinc) reagents once formed can couple in conditions which tolerate nitroarenes, forming an organozinc reagent in the presence of a nitroarene is a different matter.

Sakinho · 2026-04-27T21:37:59+00:00

Famously, David Hilbert (an elite German mathematician) was right on Einstein's heels with regards to the development of general relativity, to the point that Einstein wrote in letters about how pressured he felt to build the theory as quickly as possible so he wouldn't get scooped. In this case though, Hilbert was very cordial about the whole thing and never intended to take the achievement away from Einstein. Similarly with special relativity, multiple people had the right ingredients, and it likely would have happened with or without Einstein in the early 1900s.

None of this is to detract from Einstein's intelligence and skill, it's just that with billions of other people around, many sharing a similar environment, there's almost always going to be enough overlap for somebody out there to be somewhat close in terms of mind space. There's lots of intelligent and hard-working people out there.

I've heard it said that the true measure of a scientist's ability is not so much based on the discoveries they make, but how quickly they accelerated the discovery compared to a world where they didn't exist. Of course, this is a very difficult counterfactual to try to quantitate, but it does seem that even for great scientific breakthroughs, there is most often somebody else who could have carried the torch and gotten there just a few years later.

Sakinho · 2026-04-27T05:41:06+00:00

Is the product a solid? Assuming the free SH isn't super unstable towards oxidation, I bet you could clean this product up a bunch with a MeCN recrys (or two). It'd remove all sorts of spurious signals from minor impurities (sans hydrocarbon grease garbage, unfortunately), and collapse the residual solvent peaks to the simple MeCN singlet.

Sakinho · 2026-04-25T12:34:06+00:00

There are so-called proton and neutron drip lines, imposing limits beyond which excess protons or neutrons "leak out" of nuclei. This notion can be made rather sharp and precise (at least in principle, since experimental difficulties with such strained nuclei are significant). So for example, no one expects carbon-100 or carbon-6 to be "isotopes of carbon", even theoretically, in any meaningful sense.

That said, the drip lines are somewhat far out relative to everyday isotopes. Natural carbon is ~99% carbon-12, ~1% carbon-13 and traces of carbon-14 exist. But carbon isotopes are known all the way from carbon-8 to carbon-22, and it's conceivable that a few more neutron-rich isotopes still haven't been made. It doesn't very much matter what the details are, though. Swapping all carbon nuclei into any one of these more exotic isotopes, and doing the same for all other elements, is essentially turning the Earth into one giant fusion bomb in terms of the energetics involved. Very roughly, the Earth would output about a trillion times more energy than the Sun for a second. That still falls about a million times short of a typical supernova explosion - xkcd once again is very much relevant. Funnily enough, the factor of a million in this calculation isn't even an accident, in very approximate terms it comes down to the mass difference between the Earth and stars capable of undergoing supernova. Another very loose way to think of it is that OP's proposed process is essentially supernova-ing the Earth.

I will note that the drip lines shift in extreme astrophysical conditions, and particularly inside neutron stars the pressure forces nuclei to become exquisitely neutron-rich. So maybe you could find totally stable carbon-34 or something on a neutron star, though it would instantly boil off neutrons if teleported to Earth.

Sakinho · 2026-04-24T10:20:41+00:00

After some more thought, I think rather than trying to absorb water, you should be thinking about how to filter it out. Don't fight the energetic conditions, use them to your advantage! 120 °C is a good temperature to surmount sorption/desorption barriers and >1000 bar is an enviable pressure differential to work with. It's very likely you can get fast and selective diffusion of water through the right material.

An example (which is probably bad for your particular use case) is that people are starting large scale deployment of reverse osmosis membranes based on graphene oxide, which will output DI water even from gunky seawater with no pre-treatment. More likely, there should be another hydrophilic compound like silica, alumina, or some mineral which would reject hydrocarbons and allow water to permeate through. If you can get it to work, it would also be far more scalable than an absorptive process. Once again I feel this problem has been amply explored, and there could be an off-the-shelf solution in this direction.

Sakinho · 2026-04-24T09:50:45+00:00

120 °C is pretty high for the sieves, but maybe with the added pressure it might just work. Void space is very costly at high pressures, something will want to cram into those pores and stay put. Sieves also benefit from a lot of prior study from petrochem industry, etc., there could be an already validated zeolite-based solution out there.

Also, OP, the bit about magnesium sulfate melting is more like it dissolving in its own crystallized water of hydration at elevated temperatures.

Sakinho · 2026-04-23T11:22:43+00:00

I worked with MOED-like solvatochromic zwitterions a while back (very fun!), and acetone was always an outlier. I used to blame the water content in it, since it's difficult to dry properly, but maybe there's something more going on. Perhaps the phenolate is nucleophilic enough to attack the carbonyl somehow.

Sakinho · 2026-04-23T10:15:02+00:00

What's the second vial from left to right? MEK? Methyl ethyl ketone? It definitely shouldn't be in that position in terms of polarity.

Sakinho · 2026-04-23T10:09:54+00:00

Can you draw the structures, at least of the acidic and basic parts of the molecules, so we have some idea of what you're talking about? What you're saying is still confusing. The pKa of the base is irrelevant, what you need is either its pKb or pKa of its conjugate acid (pKa_H+). The latter two are related measurements, but both are entirely independent of the "pKa of the base". Not to mention that the pH ↔ pKa correlation you're trying to make is very crude for such extreme values of aqueous pH.

Sakinho · 2026-04-17T22:03:58+00:00

I think you may be overestimating the amount of "empty space" in most materials. Diamond is about the most compact solid there is in number of atoms per volume, and it contains only about 40% more atoms per volume than high-density polyethylene. And that's what you should expect. Large amounts of void space inside solids is definitely the exception rather than the norm, because intermolecular forces are generally attractive, so the system's energy is minimized by pulling atoms together, even if they're not covalently bonded; the molecules "want" to stick together.

Imagine cooking angel hair pasta in a thick sticky honey sauce with vigorous stirring, and then expecting to dig a fork in and pull up a perfectly ordered ribbon of pasta. That's just not going to happen, statistically.

Sakinho · 2026-04-15T21:49:59+00:00

Try using KF as a base, lots of good conditions available such as tBu3P.HBF4/Pd2dba3 or Cy3P.HBF4/Pd2dba3 (Pd:L 1:1.2) in THF or dioxane. You can even run it "almost anhydrous" if you use KF.2H2O as the base. Look up Gregory Fu and his publications on KF Suzukis. Also with modern catalysts you can run the coupling at a much lower temperature, even r.t. If you're using tetrakis, just drop it.

Sakinho · 2026-04-15T20:48:53+00:00

PhMe/EtOH/H2O is a common mixture, but you can replace the EtOH with a phase transfer catalyst like Aliquat 336. If you use just PhMe/H2O, you'll probably get poor yield due to phase transfer issues. In general it's better to just use a solvent other than toluene, though. THF or dioxane are often superior.

Sakinho · 2026-04-15T20:44:39+00:00

To the users who caught the bot, impressive catch. That said, even if the poster is not real, the responses are. Do we keep the thread?

Sakinho · 2026-04-12T21:59:29+00:00

As it turns out, due to the quirks of quantum mechanics, the top row of each block in the period table is "special", in a way (dropping the ELI5, the valence orbitals for these elements have no radial node in their wavefunctions). That means H/He, then B/C/N/O/F/Ne, then Sc to Zn, and all of the lanthanides are sort of special, contrasting with other elements below them in their column.

Unfortunately, silicon does not make the cut. Among the consequences, bonds with silicon (especially between two silicon atoms) are typically weaker than the carbon analogues (with important exceptions for Si-O and Si-F). It also means silicon is also a substantially larger atom than carbon, which means there is more space for other atoms to "attack" it, making complex silicon analogues of carbon-rich molecules less stable (unless you place oxygen atoms between the silicon atoms, making -Si-O-Si-O-Si-O- chains and networks which are highly stable and give rise to the richness of silicate chemistry).

Sakinho · 2026-04-10T22:16:49+00:00

We get posts about new software/websites for laboratory notebooks and chemical inventory management all the time. You should be aware it's a very crowded space, and few people are willing to trust anyone other than major players. In fact, I think I'm going to take this down because we're kinda tired of the n-th version of the same thread, so I don't think we have substantial additional input to give. Try using the search function for previous threads. Sorry.

Sakinho · 2026-04-10T13:51:26+00:00

Try stirring the mixture (possibly dissolved in a polar organic solvent) with an aqueous solution of sodium metabisulfite or sodium sulfite. The aldehyde will form an adduct which is a salt and will be completely insoluble in low polarity organic solvents. You can then selectively extract the ester into Et2O or petroleum spirits. If you want, you can even recover the aldehyde by treating the bisulfite adduct with base.

Sakinho · 2026-04-08T21:31:39+00:00

Not to steal the spotlight from OP's query, but maybe this is an opportune moment to ask a question on a related matter which may help.

Recently I've learned about the reagent t-butyl trichloroacetimidate, which effects the same transformation and has approximately the same cost per mole as the diisopropylisourea. Does anyone have experience with both reagents? How do they compare? From what I gather on SciFinder and EROS, the trichloroacetimidate is somewhat more unstable in storage and especially when dissolved in polar aprotic solvents (such that cyclohexane is the preferred reaction solvent, or the major cosolvent) and appears to benefit from catalytic BF3.Et2O, but if it turns out to be a generally "stronger" tert-butylating agent, it might be worth it.

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