Hello everyone, I'm new to this forum and was planning to do the Baeyer-Drewson indigo synthesis. Is there a way of preparing a good quantity of it
(like 250ml)? Have considered KMnO4 and chromate/dichromates but can't buy unless I get a permit (except for crappy 'medical use' KMnO4 that contain
like 25% KMnO4 and other crap that is not listed) and Cu catalyzed dehydrogenation but concerned about ketene production and also couldn't find any
literature about what temperature starts ketene production that would be dangerous. I have tried the Ca(Ac)2 method but doing it on a 250ml or so
scale would be tiring. Considered doing an MPV with acetaldehyde (I can buy a solution of 40% acetaldehyde in water for around 4USD (when you could
get it, chinese chemicals are cheap)) but didn't do it yet. Also considered using bleach but didn't find any related resources. Any suggestions on the
problem? Thanks! (Sorry for the weird problem, it's the strict chemical regulations in china that is the problem, so I only could buy isopropanol but
not acetone)-Garry63566Garry63566 - 28-4-2021 at 08:54
Also if anyone in China (and understand Chinese) viewing this thread, here's a website great for buying (some) reagents: https://www.tansoole.com/index.html , but the ones noted drug precursors(even acetone, toluene, HCl, H2SO4, etc. but I guess they count maybe) and
explosives precursors (like HNO3 and nitrate salts are listed) need a license to purchaseJenks - 28-4-2021 at 10:14
Agreed, that is a strange problem! If you could have it shipped in, that would be one solution. Another would be to find a product that contains it,
like nail polish remover of PVC cleaner, and distill to isolate the acetone. Can you use butanone instead? Oxidation of isopropanol is the next worse
choice, but it would take a lot of oxidant. Methanol and ethanol can be oxidized to the aldehyde by oxygen in the presence of a glowing platinum wire.Garry63566 - 28-4-2021 at 21:07
Sadly, Nail Polish Removers or lacquer thinners or PVC cleaners and etc. are mostly DCM, ethyl acetate, and xylene or acrylic acid, etc. And butanone
can't be used in the reaction(sadly it is also banned). Guess I would try to oxidize isopropanol with platinum catalyst (probably will use Astral's https://youtu.be/iaNSH89gpPk) or with Cu mesh later.Fyndium - 28-4-2021 at 21:53
Are they really banned in China? What is available then?
And - no offence - I presume that if you get stuff through a company - or just simply a bit more unofficial ways - you can get stuff even more easily
than in most western states. I find it somewhat macabre that you can order dirt cheap glassware and chemicals online with one click, but you couldn't
buy them otc there?
China is, after all, THE place that everything is made in. And you can't really make s*it without reagents and stuff.Garry63566 - 29-4-2021 at 02:01
Yep, trying to do amateur chemistry is damn hard in China, especially the last few years. I get stuff through online orders from companies (If I could
get them). If chemicals could be bought they are dirt cheap but most of them can't, even the ones that are quite useful but still have a little use in
drug production (like technically you can make drugs from acetone, MEK, etc. so they are banned). China is extremely strict on purchasing reagents
that are even barely related to drug production. (e.g. category 3 of "drug precursors" (so you need a license to buy) include toluene, acetone, MEK,
HCl, H2SO4(although battery acid is not regulated idk why), and KMnO4(although small purchase like 50grams of impure KMnO4 for antiseptic use does not
need a license)) and lots of stuff are banned because they are "explosives precursors" too (like Mg turnings, Al/Zn powder, nitrates, >8% H2O2,
etc.)
I think when companies are shipping internationally it's according to the law at the country they arrive in (idk) so probably much easier to buy than
OTC here, and it really sucks.
Sorry for the rantGarry63566 - 29-4-2021 at 02:13
So getting lots of reagents are incredibly hard so lots of alternative ways of getting it are spread around some forums (also the Chemistry forum in
China that used Baidu Tieba(basically a platform by Baidu for ppl to create forums) got exterminated a long time ago), as some things are dirt cheap
and some things are just impossible to buy. I was just planning to buy 500g p-TsOH*H2O (which only costs like 3.4 USD(here it's 22CNY)) and use a
Clevenger apparatus on heavy return to stock up on some toluene to prep for the indigo synthesis (which from my research nobody did and recorded the
process as p-TsOH is usually quite expensive and toluene is relatively cheap)Garry63566 - 29-4-2021 at 02:28
Bringing the topic back to acetone, I am now considering both oxidizing isopropanol and cumene process. I could buy cumene and do the hydroperoxide
route and also stock on some phenol (https://sci-hub.ee/10.1016/s0009-2509(54)80006-6) or oxidize isopropanol by catalyzed oxidation/dehydrogenation.
I'd probably try oxidizing isopropanol this weekend and if there are resources that I could look into could you post it here, thanks!njl - 29-4-2021 at 02:46
This is just the beginning of an idea (can't give you any conditions at the moment), but perhaps the hydration of methylacetylene catalyzed by Hg(II).
Methylacetylene is available from MAPP gas canisters, used as a hotter burning alternative to propane for torches. Hydration of terminal alkynes like
methylacetylene gives methyl ketones, in this case acetone. The reaction typically takes place with H2O, H2SO4, and HgSO4. Since the alkyne is a gas,
this will be more complicated.Jenks - 29-4-2021 at 10:18
That reminds me of the thread about trying to make acetic anhydride by heating acetate salts, but getting acetone instead. I don't know if this
annoying side reaction can be made a production method.njl - 29-4-2021 at 10:23
Ketonic decarboxylation is a known reaction that has been thoroughly documented. While it may be a side reaction in some conditions, it has been used
and optimized to make some simple ketones. Nile Red has a video making acetone from calcium acetate. It just isn't very convenient because it requires
high temperatures while only giving mediocre yields.Texium - 29-4-2021 at 12:35
Methylacetylene is available from MAPP gas canisters, used as a hotter burning alternative to propane.
Well,
it isn’t anymore. At least not in the western world. I don’t know about in China, but MAPP gas here hasn’t contained methylacetylene since 2008.
Since then it’s been straight propene, which is arguably a more useful chemical feedstock, though it doesn’t burn quite as hot as the old mixture
did. They still call it MAPP for brand recognition. I still have an old pre-2008 MAPP cylinder that I’m saving in case I ever need methylacetylene
for some reason.clearly_not_atara - 29-4-2021 at 17:54
What a strange problem to have. If you are not planning to use acetone as a reagent (as for indigo), just avoid it; it is generally a solvent of
convenience.
Iron acetate releases acetone at 280 C vs around 340-350 for the calcium salt. This may be a little easier. I don't know where you're going to get all
that nitrobenzaldehyde.
Potassium dichromate is not too hard to make if there are reasonable sources of potassium and chromium available. It precipitates from cold water
below pH 6 (solubility 5% w/v).Garry63566 - 29-4-2021 at 19:34
I probably will resort to ketonic decarboxylation and probably do it in a stainless steel can with a glass adapter head. I have access to very cheap
glacial acetic acid (sold as a food additive with 25CNY per 2.5kg) so boiling the solution out without the extra water and heating with a gas burner
would be an option. I would probably still try catalytic dehydrogenation though as I don't think ketonic decarboxylation would work when trying to get
MEKGarry63566 - 29-4-2021 at 20:36
I don't know where you're going to get all that nitrobenzaldehyde
I think I would make dichromate myself but I don't want to use it on making acetone as I think it's kind of a waste of labor if cheaper and more
convenient methods are usable. For nitrobenzaldehyde probably will try to nitrate p-TSA and disulfonate then oxidize the methyl group to aldehyde by
chromyl chloride in CS2 (or methyl to aldehyde by adding Cl with UV and then getting alcohol and then oxidizing with pyridinium dichromate) and it's a
process and a halfGarry63566 - 29-4-2021 at 20:39
Also, I choose to nitrate p-tsa but not toluene as I could buy p-tsa but not toluene and I don't want to be nitrating the 4 position anywaykatyushaslab - 5-5-2021 at 11:09
That reminds me of the thread about trying to make acetic anhydride by heating acetate salts, but getting acetone instead. I don't know if this
annoying side reaction can be made a production method.
There is a Nile Red video on dry distilling calcium acetate to produce acetone (which I guess would need to be re-distilled). I've been intending to
get around to trying this at some point largely out of academic curiosity.
