Phenylacetone (P2P) synthesis from benzaldehyde with butanone

[MadHatter]

Thank you so much for the easy and detailed synth description!
How about the hydrogen peroxide, could that be substituted? It's a really controlled chemical nowadays, and a bitch to synthesize yourself. Its mainly there as a catalyst in the reaction between the glacial acetic acid and the 3-methyl-4-phenyl-3-buten-2-one, right? What could be a good substitute?

 

[TheNut22]

It's worth looking in different online stores or normal street stores that sell H2O2 for growing plants.

 

[lalalander]

Everyone says this method has flaws. Has anyone ever really gotten significant yields with this method?

 

[Ortist]

You can also distill P2P with water, but it is very slow. However you MUST distill methyl-phenyl-nutenone under vacuum because there is significant amount of crap and MPB will not distill with water

 

[TheNut22]

This was just my polymerized P2P bullshit! And I could not distill my P2P. That's why my Leuckart didn't work any of those times I tried, and oh boy I tried..

 

[TheNut22]

When I extracted my P2P with ethyl acetate, I put little bit of drying agent in, and put it in my fridge.
I looked the liquid, and when it was about 3 hours i the fridge, the bottom layer was full of clear oil.
Is that my P2P? Can I really extract with this way?!

 

[TheNut22]

I was just water in the bottom. But my P2P was in the ethyl acetate.

 

[TheNut22]

BUT, it all went down the toilet, because it was NOT P2P. P2P is not soluble in ethyl acetate. I think it was some other product, because I did the hydrogenation of acetoxy, wrong way. Acetoxyphenylpropene I think is soluble in ethyl acetate. Correct me if I'm wrong. I dissolvne all in xylene now, 'cause they are both soluble in xylene, so I also save money.

 

[OrgUnikum]

P2P is very well soluble in EtOAc - Ethyl Acetate. It is also soluble in Benzene, Toluene, Xylene, Ether, DCM but it is only sparingly soluble in Naphta aka Shellsol aka Wundbenzin/Reinigungsbenzin. A mixture of Ethyl Acetate and Naphta 50/50 works great.

 

[TheNut22]

I read some "data" some time ago that it is just sparingly soluble in ethyl acetate. OK. Thanks.
But now I'm good. Thank you OrgUnikum for your reply also for my P2P hydrogenation. Now it went very well, with putting more solution to the base, in acetoxyphenylpropene hydrogenation. I got yellow, very "honey-like" smelling solution in xylene. This is the first time the solution is not red, because I followed your instructions to put more solution. Thanks!

 

[Ketaholiker]

Hello ,

can i go from 3-Methyl-4-phenyl-3-buten-2-one and do a electro oxidation.
Possible?

EP0247526: Electrolytic 3,4-Dimethoxyphenylacetone Preparation - [www.rhodium.ws]

Electrochemical process for converting olefins to ketones

This maybee helps also

Electrochemical Reduction of Nitroalkenes to Oximes and Amines - [www.rhodium.ws]

OTC would be super hope you guys can help electro reduction/oxidation its really cool and unsupect xD

Have a nice day

 

[TheNut22]

All those reagents to make 3-Methyl-4-phenyl-3-buten-2-one are OTC.
I'm not going to name any brand for to obtain that benzaldehyde, because "they" will take them out of those shelves, immediately. Or, even if i'm wrong about that, it's better to be little cautious about those precious reagets.

 

[TheNut22]

BUT, look the benz-hyde from artificial flavouring shelves in stores.

 

[OrgUnikum]

No. This are different oxidations. You need a BV, a Baier Villinger oxidation.

 

[handle]

Great let's try this one.
Step 1, underway.
45g Benzaldehyde + 200ml M.E.K bubble the HCL gas from 25ml H2SO4 over 25ml Hydrochloric acid. Turned bright red in about 30mins, now stirring.

 

[TheNut22]

Now that I have over 100 grams of water and acid/base -purified, but wet MPB (collected from few reactions),
I'm going to dry the crystal solution into crystals, that don't melt in room temperature. I can post a picture of that, and I can post a picture of the acetoxyphenylpropene as well, with the yields.

 

[TheNut22]

I don't know why this picture went sideways, but you can see those bubbles in there, and
the cool colour what I get always in the peracetic oxidation process. The oxidation time was 24,5 hours.

 

[TheNut22]

I got 100 grams of acetoxy phenylpropene from that 100 grams of MPB. Now I'm happy!

 

[TheNut22]

When I put the P2P solution in xylene in the fridge, some particles come out. Do those particles belong to P2P, or can I filter them out? Last time I filtered them out. Was it a mistake, or is it wise to filter them out again? The solution is still raw, and not purified.

 

[TheNut22]

I have to make clear that those are not like little particles (my rusty english), but like a mass that will fall to the bottom of my beaker in the fridge. In room temp, those pieces no longer dissolve at room temperature. Can someone explain, and give guidance to me, please? I would be very happy, because I do not want to make any mistakes, 'cause I have so much P2P in the solution right now.

 

[TheNut22]

I washed the solution with ~ 12% HCL-solution x 4. and got almost clear solution. Washed many times with water also. Dried with MgSO4.

 

[OrgUnikum]

The product of the BV oxidation, the vinyl-acetate is miscible with Xylene, the P2P formed by hydrolysis is also miscible with Xylene, so anything what drops out is just crap. Filtration is a must if any of your intermediates or the final product in solvent is not clear but cloudy or turbid.

 

[TheNut22]

Thanks again. You have helped me alot with this whole synthesis, and the same time this has been a huge learning process.

 

[OrgUnikum]

You do not have to base this extract. P2P does not like water and xylene the same. So just wash the P2P/Xylene twice with plain water, say add water in the sep funnel, shake, shake a lot more, wait for separation, separate and repeat. If the Xylene layer stays turbid - no problem, the water layer must be clear before you separate. Then you add brine, saturated NaCl solution, the same amount as xylene and shake once and wait. And Voila! Clear water layer AND clear top layer. The salt sucked the water from the xylene.
Now proceed as you wish, it depends on what you you want to do with the P2P and other things.

 

[OrgUnikum]

PS: Oh maybe I was confused, did you just talk about the hydrolysis when adding the 20% KOH? If so, well, this is too strong, to highly concentrated and well I found something and here it is:


0,1 M is 4 gram of NaOH per liter water. 20% KOH is over 200 gram per liter. You see the difference?
Practically I advice to use between 0,2M to 0,5M NaOH (or KOH) what is 8 to 20 gram per LITER of water. I tried 10 gram and it worked fine.
Also the formyl ester must be mostly free of xylene for the hydrolysis, for sure if you use stronger base concentrations.If you keep all xylene from extraction you better also add a good amount of alcohol.
Acid hydrolysis though needs refluxing in strong mineral acid for hours. But of course P2P is much more stable towards acids then it is towards bases.

Here you see what strong bases do to P2P: The infamous red tar. This resulted lately from an attempt to steamdistill P2P from a basic solution which over time got more concentrated and then this was what I got. P2P polymere by base catalyzed self-condensation.

 

[TheNut22]

No, the hydrolysis I made, I made it wayyyy more diluted KOH-solution.

 

[TheNut22]

Now I have perfecty clear yeallow P2P oily liquid.

 

[TheNut22]

This is what I meant in the first place: Why did my P2P in xylene solution go almost completely mush when I put the one and only 20% KOH solution in? It was thick mush, almost half of it. And the more I poured the diluted HCL solution (about 12%) in, that doughy lump melted back into that solution? So it happened at room temperature. I had to add those diluted acid solutions a total of six times before I got a really clear P2P solution in xylene. Of course I washed it many times with deionized water. And I noticed soe impurities were little bit soluble to water, but in sepatary funnel, those little particles went to water phase but fell on the bottom. But with those acid/water washes it is now completely clear, but if I put it in the fridge, some small particles still appear in the solution. I haven't experienced this before, and if I had put just one more base in the beginning the whole solution would have been not solution anymore. Just a big clump, mushy big cake or something (english is not my language). My AI-assistant in chemistry told that mush is PROBABLY the P2P that is precipitating out, but I cannot trust my AI assistant nothing but it doing so mathematical stuff.

P.S Sorry for long post. I just tried to explain.. and half of my P2P is in steam disitill right now..

 

[TheNut22]

I know this has to be hard question, because I haven't found answer to this anywhere.

 

[TheNut22]

But where, or how there is some vinyl acetate in my BV oxidation solution as a by product?
How is it formed? I used: 30% H2O2 + GAA, and 0.1 moles of H2SO4 + MPB of course.
And now I forgot that the sixth acid wash made it so clear that there is nothing floating in my P2P solution when it's in the fridge now, I'm sorry. My memory fails. Many many times throughout the days...