1-Phenyl-2-propanone (P2P) synthesis from Diethyl(phenylacetyl)malonate

[w2x3f5]

This reaction also goes with phosphoric acid

 

[LordCrackingtonson]

The original synthesis on page 1 calls for 7.5ml concentrated sulphuric acid.

If you substitute 85% phosphoric acid instead, how much would be required?

 

[w2x3f5]

I did several times, mixed the oil 1 to 1 with phosphoric acid, heated it until the gas evolution stopped. Unfortunately, I did only a few hydrolysis and did not record.

 

[LordCrackingtonson]

Did you use glacial acetic acid and phosphoric acid together.. or just equal amounts phenylacetylemalonate and phosphoric acid?

 

[w2x3f5]

H3PO4 only

 

[41Dxflatline]

Some bees buzzed that diethyl(phenylacetyl)malonate could be used directly in a Leuckart reduction without first being converted to P2P

 

[w2x3f5]

during the hydrolysis of malonate, impurities in the ketone, the color of the ketone is more dirty than with glycidate

 

[w2x3f5]

I use with H3PO4 hydrolysis, but one or two times

 

[Monstapoint]

Great & useful Information. Thanks

 

[MarinaX]

Love it

 

[OrgUnikum]

Guys, do not fall for the cult of the holy reflux. Refluxing has no worth in itself except for the illusion of something happening which it creates.

With H2SO4 and Oxalic acid (best) but Phosphoric Acid and about any organic acid like Acetic or Formic or Citric work one gets next to quantitative yields if one heats up the mixture slowly over two hours to NOT MORE then 95 °C, holds it there for 30 minutes and then let it cool down. Add a small amount of solvent other then DCM (Toluene, Xylene, Ether) as organic acid may fall out and so collecting from top is advised. Petrol Ether 40/60 can be used and not much is needed but you get THREE layers in the end: Top layer is Pet-Ether with P2P dissolved. Middle layer is P2P with Pet-Ether dissolved*. And below is the acid mix (which can be re-used btw. without problems).

*Sounds funny but thats how it is: Both, Pet-Ether and P2P dissolve some of the other one but thex are not freely miscible. And so you get the three layers which drove me next to nuts already a long time ago. Until I figured this out.......

200 g Oxalic Acid Dihydrate
300 ml Water
100 ml H2SO4 37% (battery acid)
not all Oxalic Acid will dissolve - no problem
With this one can process a minimum 200 ml 20230 red oil
Really strong stirring all the time is needed.
The water/acid mix can be re-used.
Not over 95 °C gives light yellow P2P directly without steam or other distillation.
When you use a sep-funnel you best separate as long its still hot and the oxalic does not drop out.Or you put it in a beaker in the freezer with the bottom of the beaker touching the cold so it starts to crystallize from there. If you do this you need no solvent at all, the acid and watere crystallizing from the bottom will drive the P2P to the top and you can just pour it out after two or three hours and NO P2P will be left back.

I did a lot of work on this one, lol

 

[w2x3f5]

indicate the yield of the substance p2p please.
do you have red oil? strangely, I had yellow oil under the same number.

 

[OrgUnikum]

20230-59-6 - Diethyl(phenylacetyl)malonate is supposed to be a dark red oil, it is also so described in the scientific literature.
Its molecular weight is ~278 g, the molecular weight of P2P is ~134 g this says that you can get a maximum of 134 g P2P from 278 g 20230-59-6 - Diethyl(phenylacetyl)malonate or 480 g from one kilo, the maximum theoretical yield being 48 %. I got 45 g pure steamdistilled and dried P2P from 100 g BMK 20230 after finalizing the method and thats as good as it gets, 93 % of whats possible is more then ok with me.

The 20230 is a bit a heavy compound and yields therefor per kilo not so much as other BMKs and its therefor not really cheap but it produces excellent quality easily.

I attach the article where the 20230 is first time synthesized and converted to P2P, look at the very end for the procedure. I replaced the acetic acid with oxalic acid as the oxalic has certain protective properties including scavenging metal ions (often in consumer grade HCl or H2SO4) which could catalyze decomposition of the P2P

PS: I just realized that if the 20230 was prepared by a different pathway then it might not be red but of an milder color, prepared as described in the article its red.

 

[w2x3f5]

Most likely, oil of varying degrees of purification, although I only hydrolyzed this substance a few times, Google agrees with me that there is red and yellow on sale. It’s good that you found it.
Please don't write 48 percent yield - that's not true, the theoretical yield is always 100 percent. But in terms of moles, you counted everything correctly.
Oxalic acid mixed with acetic acid works, but it seems to me easier with phosphoric acid)))
93% good yield!

 

[OrgUnikum]

Well I believe it is important that people know that they can in the best case get 480 g P2P from 1000 g of this BMK whats 48 % w/w.

 

[w2x3f5]

It sounds so much better

 

[ZMI_AA0B]

Teacher, may I ask which type of red oil it is

 

[ZMI_AA0B]

Excuse me, is it Türkiye red oil?

 

[ZMI_AA0B]

Teacher, can phenylacetone be synthesized using only oxalic acid, water battery acid, and these three materials

 

[MarinaX]

Appreciate

 

[rothschild33]

Performed the 20320 -> PAA and Phenylacetone method,


1. An alkali aqueous solution 50 % is prepared in advance so that it has time to cool down. Sodium hydroxide 115 g (NaOH) is dissolved in water 115 g and cooled down to room temperature.
2. The cooled NaOH aqueous solution of is poured into a dropping funnel and this funnel is installed onto a reactor.
3. Diethyl(phenylacetyl)malonate 800 g is poured into the reactor. The reaction is carried out at room temperature but a forced cooling can be used during the hydrolysis.
4. A stirrer is turned on and NaOH aq solution adding is begun slowly. Reaction temperature has to be controlled (the mixture is self-heated). As the solution is added, reaction mixture (RM) color is changed and thickened until it is become completely thick and lumpy. The lumps is broken into a homogeneous mass.

After adding the NaOH, the mixture turns lighter and lighter over the course of minutes getting thicker. Then, at one point the mixture turns back into the color of 20320-59-6.

This was the mixture color after a few minutes of NaOH addition

As time progressed, it started reverting back to the original color:

Then afterwards it just remained in this state:

Anyone know what I can do to fix this, any trial and error / troubleshooting methods?
Also what should I research, what kind of reaction is this, so I could dig deeper into the optimal reaction condition?

 

[rothschild33]

update: increased the added NaOH solution by 50% and it worked!

 

[qwe111]

Sir: Have you successfully obtained pure phenyl acetone? Are there any additional steps? Have the ratios of any solvent additions been changed?

 

[OrgUnikum]

BMK 20230 must be done with acid alone, with base you will get not P2P but something else. The author of the original paper used diluted H2SO4 and acetic acid but any mineral acid works, better together with an organic acid. I used HCl or H2SO4 with oxalic acid and it worked great.

Attached the article but beware! The method is not optimized at all. The addition of lye to render the reaction alkaline at the end is outright dangerous as there is a good chance you will polymerize the P2P this way )some of it at least). Its also unnecessary. Also no need to reflux for 3 hours. 90 °C for 30 minutes is fine, but heat it up to this temperature slowly (2 hours).

 

[Xiao hua]

can diethyl malonate instead of diethyl (phenylacetyl)malonate?

 

[HIGGS BOSSON]

No

 

[hy16a]

I don't understand the meaning of 0.2 moles at all. Can 99%CAS 20320-59-6 diethyl phenylacetylmalonate be used directly?