Phenylacetone (P2P) synthesis from benzaldehyde with butanone

MadHatter

Don't buy from me
Resident
Joined
Dec 4, 2021
Messages
442
Solutions
1
Reaction score
395
Points
63
I guess what I'm really wondering about is the stochiometry of this reaction. In other write-ups of the bayer-williger I can't seem to find this enormous amounts of GAA. Can somebody help me with the rationale? I'm really close to trying this one out, but the amount of GAA is problematic.
 

billythekid

Don't buy from me
New Member
Joined
Apr 18, 2024
Messages
13
Reaction score
2
Points
3
I guess what I'm really wondering about is the stochiometry of this reaction. In other write-ups of the bayer-williger I can't seem to find this enormous amounts of GAA. Can somebody help me with the rationale? I'm really close to trying this one out, but the amount of GAA is problematic.
MadHatterthis amount of gaa is a lot and my best guess as to why is that preparing Peracetic acid in situ (during the reaction) and without a catalyst is inefficient so the chemist overcompensates to help with this, also GAA is used here as the solvent
by making the peracetic acid days before and testing the available oxygen content you are likely to get better results. This being said, I have seen professionals use this method and only get at best 35 to 65% of finished product. so an inexperienced chemist is likely to get even worse and a newbee is likely to fail or even worse hurt themselves. I recommend reading and studying and start small
make sure you thoroughly clean your finished reaction mix at the end of each step, Do not exceed -5c in the aldol condensation let mek/benzaldehyde stir overnight in the fridge after gassing.
do not exceed 60c in the Bayer villager. and research other oxidizers because I get better results with a different one.
 
View previous replies…

TheNut22

Don't buy from me
Resident
Joined
Feb 12, 2024
Messages
53
Reaction score
25
Points
8
Have you ever tried oxidizing MPB with oxone? In thevespiary it was written that by oxidizing with oxone, 85%> yield was obtained.
lalalanderMaybe I will try the oxone if the yield is so high! I've read those thevespiary/hive forums, and now I'm going with those instructions, because in these instructions here, I haven't done this succesfully.
 

TheNut22

Don't buy from me
Resident
Joined
Feb 12, 2024
Messages
53
Reaction score
25
Points
8
I got ~ 7 grams of sweet smelling little bit yellow P2P from 35 grams of MPB. My peracetic oxid time was around 24 h.
Now I've done the Leuckart reaction, at 32 h time. I have my n-formyl --... now. I am proceeding hydration with base (KOH pellets with pure water, 5 hours reflux), with that kind of reaction some paper claimed as good as 95% yield!?
I don't know, but this time, the look (got purple solution, but it's OK) and smell is different from my many attempts to proceed the Leuckart reaction, but I think I didn't have P2P then, but now I certainly did! Yes! Just never give up!
Because this was my 22:nd attempt.. :)
TheNut22Can I really distill the P2P in normal atmospheric pressure without ruing the P2P?
 

lalalander

Don't buy from me
Resident
Joined
Jun 17, 2023
Messages
40
Reaction score
13
Points
8
Can I really distill the P2P in normal atmospheric pressure without ruing the P2P?
TheNut22According to the articles I read, you can do it, but the loss in yields will be high. And some articles suggest that P2P will degrade before the temperature is reached.

Steam distillation looks easy and clean.
 

Fenster

Don't buy from me
New Member
Joined
Oct 26, 2022
Messages
92
Reaction score
24
Points
8
Aldol Condensation.

The directions for this are in Organic Reactions

200 gms of Benzaldehyde and 300 gms of Methyl Ethyl Ketone are mixed in a 1 litre beaker and cooled below 5°C. HCl gas is bubbled through until 40gms has been added. The mixture goes from a clear solution to a red colour and becomes turbid so that you can't see through it. The mixture is kept over night and becomes a brown colour. It is washed with water and then 10% NaOH solution, the organic layer seperated and distilled. At 240°C a yellow oil comes accross and the temperature gradually rises to 260°C.

The oil can be crystalized by cooling in the freezer overnight. This in itself does not induce crystalization but if you also put a spoon in the freezer and then dip it in and out of the cool mixture you get some seed crystals that induce crystalization. The mass turns from an orange oil to sulfur coloured crystals, mp 38°C, 180 gms (Methyl Phenyl Butenone.

This write up seems to be more inline with what I am seeing. Has anyone actually tried to extract with solvent from the organic layer. Using chloroform won't work, as it's miscible with the organic layer. Unless I'm missing something the write up needs to be tested and modified.

Anyone tried this synth before.
 

TheNut22

Don't buy from me
Resident
Joined
Feb 12, 2024
Messages
53
Reaction score
25
Points
8
Aldol Condensation.

The directions for this are in Organic Reactions





This write up seems to be more inline with what I am seeing. Has anyone actually tried to extract with solvent from the organic layer. Using chloroform won't work, as it's miscible with the organic layer. Unless I'm missing something the write up needs to be tested and modified.

Anyone tried this synth before.
FensterOK. Just heat the benz-hyde and MEK with hydrochloric acid about 3-5 hours. Temp: 90-110 C.
Just thank me. :)
 
View previous replies…

TheNut22

Don't buy from me
Resident
Joined
Feb 12, 2024
Messages
53
Reaction score
25
Points
8
My crystal liquifies at room temperature, how do I solve this problem
CbisonI put the whole thing with liquid and crystals to pyrex dish and little bit 96% ethanol and heat it, so all the material goes to liquid form. When the ethanol boils, it removes extra water from the mixture. Then I put it back in freezer in 100 ml measuring flask. Let it stay in the measuring flask in freezer from a day.
All the side products (dark liquid) is then in upper layer, and I pour it down the drain. Then I heat the flask little bit and almost always there will form a water layer at the bottom of the measuring flask. I suck the water out with my pipette, and put it again in the freezer for about a day again. It will form side product oil again in the upper layer. Down the drain again. Now you should have crystals that don't liquify in room temperature. It goes maybe little bit like goo, but it is what it is.
 

TheNut22

Don't buy from me
Resident
Joined
Feb 12, 2024
Messages
53
Reaction score
25
Points
8
My crystal liquifies at room temperature, how do I solve this problem
CbisonMelting point of methylphenylbutenone is: 13.04°C, and room temperature is about 22°C, at least in my
apartment, so there you go. And I finally found the melting point, because I was wondering about it too.
 

Cbison

Don't buy from me
Member
Joined
Nov 29, 2023
Messages
11
Reaction score
0
Points
1
I put the whole thing with liquid and crystals to pyrex dish and little bit 96% ethanol and heat it, so all the material goes to liquid form. When the ethanol boils, it removes extra water from the mixture. Then I put it back in freezer in 100 ml measuring flask. Let it stay in the measuring flask in freezer from a day.
All the side products (dark liquid) is then in upper layer, and I pour it down the drain. Then I heat the flask little bit and almost always there will form a water layer at the bottom of the measuring flask. I suck the water out with my pipette, and put it again in the freezer for about a day again. It will form side product oil again in the upper layer. Down the drain again. Now you should have crystals that don't liquify in room temperature. It goes maybe little bit like goo, but it is what it is.
TheNut22So heat is applied to boil off excess solvent then allowed to cool for crystallization to occur. Do you think one can proceed to Baeyer villager reaction without crystallization MPB?
 

Irving Langmuir

Don't buy from me
Resident
Joined
Jan 23, 2024
Messages
8
Reaction score
5
Points
3
Hi everyone !

I've tried this synthesis twice, and here's my conclusion on this one.

Firstly, I'm far from being a trained chemist, so what I say should be taken with a grain of salt. Feel free to correct what I say.

The reactions and mechanisms are the result of my research and my understanding of synthesis, and are therefore also open to criticism.

I just saw that a lot of people had already discussed the subject, so I hope my post won't be redundant. Also, the link at the end of my post has already been posted on the topic. Sorry if you don't learn anything from my post.


Step 1: crossed aldol condensation :
Normally we use a small excess of MEK in this reaction because ketones can self-condense, but this reaction is thermodynamically devafable, and will be done up to a maximum of 5% in the literature I've been able to find. Nevertheless, according to this paper, benzaldehyde can react with the final product, which would greatly lower the yield, hence the use of excess MEK to make sure that the benzaldehyde reacts with the right molecule. (Moreover, according to the same paper, distillation between crossed aldol condensation and Baeyer-Villiger oxidation is not useful, as the by-products will not react during the Baeyer-Villiger oxidation and can be eliminated with the next distillation). I wondered whether it wouldn't be better to add the benzaldehyde drop by drop, which would make sure there was an excess of MEK, and thus prevent the benzaldehyde from reacting with the newly formed product. And since the aldol self-condensation of ketones is not very favorable, proceeding in this way may be better for yield. But as I said, what I'm saying needs to be verified.

As a catalyst we can normally use either an acid or a base for aldol reactions. I assume, however, that here we're using an acid to avoid a Cannizzaro reaction, because benzaldehyde is non-enolizable. By using an acid catalyst, we go through the formation of an enol instead of the enolate.

As an acid catalyst, I tried a strong addition of concentrated H2SO4 the first time I did this reaction, and the second time I only added a few drops. The difference I noticed between the two was that if too much H2SO4 was added, the product polymerized, making distillation almost impossible due to bumping.

Crossed aldol condensation will lead to 3-methyl-4-phenyl-3-buten-2-one.

For Baeyer-Villiger oxidation, I wanted to try perborate or sodium percarbonate. The only problem I saw with using sodium percarbonate was that it would react with the GAA and gradually neutralize it. And indeed this is a pretty bad idea, having tried it on a small scale. Percarbonate has trouble solubilizing, and needs a medium containing a little more water. Once that's done, you have to be careful not to release too much CO2. Peracetic acid is formed in situ and reacted with 3-methyl-4-phenyl-3-buten-2-one. To make my percarbonate solubilize, I added a little H2O2. But I'd say, if you don't have 50% H2O2, don't waste your time on this synthesis. And that's my conclusion. Although this synthesis may seem attractive, it's tedious and labor-intensive, especially with all those vacuum distillations (I've tried without, it works, but leads to working with high temperatures, and I've even managed to destroy product that way!). So I'd advise anyone to turn to another synthesis method. I managed to get what I think was the desired product in the end, but in my opinion not enough to justify the whole procedure. For those who want to know more, I recommend reading the paper, searching for "Two dogs aldol", learning about the mechanisms of aldol reaction, baeyer-villiger oxidation and hydrolysis of esters.



 

WillD

Expert
Joined
Jul 19, 2021
Messages
645
Reaction score
915
Points
93
Hi everyone !

I've tried this synthesis twice, and here's my conclusion on this one.

Firstly, I'm far from being a trained chemist, so what I say should be taken with a grain of salt. Feel free to correct what I say.

The reactions and mechanisms are the result of my research and my understanding of synthesis, and are therefore also open to criticism.

I just saw that a lot of people had already discussed the subject, so I hope my post won't be redundant. Also, the link at the end of my post has already been posted on the topic. Sorry if you don't learn anything from my post.


Step 1: crossed aldol condensation :
Normally we use a small excess of MEK in this reaction because ketones can self-condense, but this reaction is thermodynamically devafable, and will be done up to a maximum of 5% in the literature I've been able to find. Nevertheless, according to this paper, benzaldehyde can react with the final product, which would greatly lower the yield, hence the use of excess MEK to make sure that the benzaldehyde reacts with the right molecule. (Moreover, according to the same paper, distillation between crossed aldol condensation and Baeyer-Villiger oxidation is not useful, as the by-products will not react during the Baeyer-Villiger oxidation and can be eliminated with the next distillation). I wondered whether it wouldn't be better to add the benzaldehyde drop by drop, which would make sure there was an excess of MEK, and thus prevent the benzaldehyde from reacting with the newly formed product. And since the aldol self-condensation of ketones is not very favorable, proceeding in this way may be better for yield. But as I said, what I'm saying needs to be verified.

As a catalyst we can normally use either an acid or a base for aldol reactions. I assume, however, that here we're using an acid to avoid a Cannizzaro reaction, because benzaldehyde is non-enolizable. By using an acid catalyst, we go through the formation of an enol instead of the enolate.

As an acid catalyst, I tried a strong addition of concentrated H2SO4 the first time I did this reaction, and the second time I only added a few drops. The difference I noticed between the two was that if too much H2SO4 was added, the product polymerized, making distillation almost impossible due to bumping.

Crossed aldol condensation will lead to 3-methyl-4-phenyl-3-buten-2-one.

For Baeyer-Villiger oxidation, I wanted to try perborate or sodium percarbonate. The only problem I saw with using sodium percarbonate was that it would react with the GAA and gradually neutralize it. And indeed this is a pretty bad idea, having tried it on a small scale. Percarbonate has trouble solubilizing, and needs a medium containing a little more water. Once that's done, you have to be careful not to release too much CO2. Peracetic acid is formed in situ and reacted with 3-methyl-4-phenyl-3-buten-2-one. To make my percarbonate solubilize, I added a little H2O2. But I'd say, if you don't have 50% H2O2, don't waste your time on this synthesis. And that's my conclusion. Although this synthesis may seem attractive, it's tedious and labor-intensive, especially with all those vacuum distillations (I've tried without, it works, but leads to working with high temperatures, and I've even managed to destroy product that way!). So I'd advise anyone to turn to another synthesis method. I managed to get what I think was the desired product in the end, but in my opinion not enough to justify the whole procedure. For those who want to know more, I recommend reading the paper, searching for "Two dogs aldol", learning about the mechanisms of aldol reaction, baeyer-villiger oxidation and hydrolysis of esters.



Irving LangmuirExcess MEK also acts as a solvent for the reaction (except what you wrote). The release of a product without distillation is possible after dilution with water (excess mek and other impurities) and extracting the sediment in the form of oil. The oil crystallizes well into an intermediate product after recrystallization with ethanol. At this stage, we get the first stage product without complicated manipulations (it is not necessary to extract chloroform, and in general, the technique in this topic needs to be slightly corrected). We cannot use hydroxide, this will give another by-product as a result.
 
View previous replies…

Cbison

Don't buy from me
Member
Joined
Nov 29, 2023
Messages
11
Reaction score
0
Points
1
Excess MEK also acts as a solvent for the reaction (except what you wrote). The release of a product without distillation is possible after dilution with water (excess mek and other impurities) and extracting the sediment in the form of oil. The oil crystallizes well into an intermediate product after recrystallization with ethanol. At this stage, we get the first stage product without complicated manipulations (it is not necessary to extract chloroform, and in general, the technique in this topic needs to be slightly corrected). We cannot use hydroxide, this will give another by-product as a result.
WillDWilliam D. Can you pls pls explain the procedure of getting MPB crystal without doing the vacuum distillation. I have followed the steps suggested but it seems I can’t get it right. I have washed, I have neutralized, I have dissolved in ethanol and I have frozen but for some reason I don’t know why my crystal liquifies at room temperature . What am I doing wrong in this procedure. Can I proceed with the Baeyer villiger reaction without extracting the crystal? Pls your experienced contribution will be appreciated
 

TheNut22

Don't buy from me
Resident
Joined
Feb 12, 2024
Messages
53
Reaction score
25
Points
8
I'm doing now, the first time peracetic acid alone first. It will need 5-7 days to reach equilibrium.
So, I'm waiting to day 5, and proceed with my 55 g of MPB + 200 ml:s of GAA as a solvent.
All the steps is to be found at Rhodium-site.
 

Y12

Don't buy from me
New Member
Joined
May 22, 2024
Messages
1
Reaction score
0
Points
1
Is it possible to not use vacuum instead use normal destilation to saperate chloroform from intermediate/product, because the BP of them are so different. but for the last purification of P2P use steam distilation.
 
  • Free product samples

    Testing products from new vendors and manufacturers.

    Get free samples for testing now!

  • Always stay in touch with BB forum. Element/Matrix.

    Connect notifications to always stay in touch with the forum!

    Connect

Top