Phenylacetone (P2P) synthesis from benzaldehyde with butanone
- Thread starter WillD
- Start date
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.
- By billythekid
this 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.
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.
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- By lalalander
According 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.
Steam distillation looks easy and clean.
- By TheNut22
First time, I'm doing this peracetic oxidation with neutralized solution, and in the upper layer, there is some reddish orange layer, that, I think it's getting bigger and bigger by hours of oxidation. I'm keeping the temperature about 55-60 C, but it is getting harder to swirl and mix with my hands (magn.stirrer is dead), because the upper layer is so thick.
What the hell I'm doing here. It bubbles, yes. I think this is the first time my peracetic acid works, because I was keeping it in my closet for 3.5 days before this, and I neutralized the solution. Can someone explain what is happening? Am I doing OK here? This is about an hour eight.
What the hell I'm doing here. It bubbles, yes. I think this is the first time my peracetic acid works, because I was keeping it in my closet for 3.5 days before this, and I neutralized the solution. Can someone explain what is happening? Am I doing OK here? This is about an hour eight.
- By lalalander
I would not be lying if I said I know almost nothing about BV oxidation.
Right now I'm doing research to increase the yields during oxidation before I try anything. The best I've understood so far is that the reason why the yields stays around 35% is because of the amount of water in the reaction mass during oxidation.
As for the distillation, yes. It's like distilling essential oils. I assume it can be done the way you said, but it will take too long. It's definitely not practical. When P2P is refluxed (boiling), the external steam volume has to be greater than the steam volume in the reaction flask where the P2P is refluxed. You can get the required steam volume with a pressure cooker.
But you certainly don't need anything fancy like pressure cooker. A very simple setup will do the trick.
Right now I'm doing research to increase the yields during oxidation before I try anything. The best I've understood so far is that the reason why the yields stays around 35% is because of the amount of water in the reaction mass during oxidation.
As for the distillation, yes. It's like distilling essential oils. I assume it can be done the way you said, but it will take too long. It's definitely not practical. When P2P is refluxed (boiling), the external steam volume has to be greater than the steam volume in the reaction flask where the P2P is refluxed. You can get the required steam volume with a pressure cooker.
But you certainly don't need anything fancy like pressure cooker. A very simple setup will do the trick.
- By TheNut22
I noticed, that I got 30,5 grams of acetoxyphenylpropene from 55 grams of MPB, when I made the peracid, not "in-situ", but first I made it comparing to exact moles, and left the peracid in my closed for 3,5 days with, of course the H2SO4-catalyst. Then I neutralized the solution with sodiumbicarbonate to pH:7. Those are the tricks for getting even decent amount of acetoxy. Don't be fooled those "in-situ"-preparations if you're doing a scale of 10-50 grams of it.
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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.
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.
- By TheNut22
OK. Just heat the benz-hyde and MEK with hydrochloric acid about 3-5 hours. Temp: 90-110 C.
Just thank me.
Just thank me.
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- By TheNut22
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.
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.
- By TheNut22
You can also distill it from your solution mix. Someone said, just distill away all that distills 150 C and under, and throw them away. Methylphenylbutenone distills around 270-300 C at normal pressure. And you can use that yellow coloured oil in Baeyer-Williger, that is same MPB, but in different form. I haven't done that, but also my crystals will become slurry in here. It is summer, and the melting point is around 13-14 C. If my apartment temp is around 22 C, so ...
There is the possibility of steam distillation of the product. You will see what I mean by tar when you get to the extraction. Are you using chloroform or DCM?
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.
www.scribd.com
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.
Forensic Science International: David Doughty, Ben Painter, Paul E. Pigou, Martin R. Johnston | PDF | Ester | Chemical Reactions
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- By WillD
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.
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- By Cbison
William 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
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.
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.
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.