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.
Have you ever tried oxidizing MPB with oxone? In thevespiary it was written that by oxidizing with oxone, 85%> yield was obtained.
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..![]()
Can I really distill the P2P in normal atmospheric pressure without ruing the P2P?
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.
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.
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.
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.
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.
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.
My crystal liquifies at room temperature, how do I solve this problem
My crystal liquifies at room temperature, how do I solve this problem
My crystal liquifies at room temperature, how do I solve this problem
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.
So 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?
i also had a thermometer, so it was divided in half, it was very funny![]()
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.
![]()
Forensic Science International: David Doughty, Ben Painter, Paul E. Pigou, Martin R. Johnston | PDF | Ester | Chemical Reactions
Scribd is the world's largest social reading and publishing site.www.scribd.com
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.
Reagents:
Benzaldehyde 1000 g; Methyl ethyl ketone (MEK) 1000 ml; Distilled water 14.5 L; Chloroform (CHCl3) 7.6 L; Sodium bicarbonate solution (NaHCO3); Magnesium sulphate (Na2SO4) anhydrous; Glacial acetic acid 10 L; Hydrogen peroxide (H2O2) 1300 g 50 %; Sodium hydroxide (NaOH) 600 g;Equipment and glassware:
5 and 10 L Round bottom flasks; Water bath; 25-30 L Batch reactor with reflux condenser and heating system; Glass rod and spatula; Rotovap machine (optional); pH indicator paper;- Laboratory scale (1-1000 g is suitable);
- Measuring cylinders 1000 mL;
- 1000 mL x3; 2000 mL x3; 5000 mL x3 Beakers;
- Several buckets;
Step 1. 3-Methyl-4-phenyl-3-buten-2-one synthesis (cas 1901-26-4).Step 2. 2-Acetoxy-1-phenyl-1-propene (cas 24175-87-9) synthesis.
1. Benzaldehyde 1000 g and methyl ethyl ketone (MEK) 1000 ml are mixed in 5 L flask, stirred and chilled at 0 °C.
2. HCl gas is bubbled slowly through the mixture for a 1.5 h.
3. The solution is stirred for addition 1.5 h at room temperature.
4. Distilled water 2 L is added. The solution is extracted with chloroform (CHCl3) 800 ml x2, then the extract is washed with sodium bicarbonate solution (NaHCO3) to neutral pH and dried over magnesium sulphate (MgSO4).
5. Solvent is evaporated under vacuum and 3-methyl-4-phenyl-3-buten-2-one (cas 1901-26-4) is distilled under vacuum (b.p. 269.6±9.0 °C at 760 mm Hg). Reaction yield is 1000 g.
1. 3-Methyl-4-phenyl-3-buten-2-one (cas 1901-26-4) 1 kg from Step 1, glacial acetic acid 10 L and hydrogen peroxide (H2O2) 1300 g 50 % are poured into a 25-30 L batch reactor with reflux condenser, stirred and at 55 °C for 23 h.
2. Next, distilled water 10 L is added.
3. The reaction mixture is extracted with chloroform 5 L and dried over magnesium sulphate (Na2SO4).
4. Solvent is evaporated under vacuum. 2-Acetoxy-1-phenyl-1-propene (cas 24175-87-9) yield is 800 g.
Step 3. 1-Phenyl-2-propanone (P2P; cas 103-79-7).
1. 2-Acetoxy-1-phenyl-1-propene (cas 24175-87-9) 800 g from Step 2 and sodium hydroxide (NaOH) 600 g in distilled water 2500 ml is stirred at 50 °C for 12 h in 10 L flask with reflux condenser.
2. Reaction solution is extracted with chloroform 1000 ml, dried over magnesium sulphate (Na2SO4) and the solvent is evaporated under vacuum. 1-Phenyl-2-propanone yield is 650 g.
Reagents:
Benzaldehyde 1000 g; Methyl ethyl ketone (MEK) 1000 ml; Distilled water 14.5 L; Chloroform (CHCl3) 7.6 L; Sodium bicarbonate solution (NaHCO3); Magnesium sulphate (Na2SO4) anhydrous; Glacial acetic acid 10 L; Hydrogen peroxide (H2O2) 1300 g 50 %; Sodium hydroxide (NaOH) 600 g;Equipment and glassware:
5 and 10 L Round bottom flasks; Water bath; 25-30 L Batch reactor with reflux condenser and heating system; Glass rod and spatula; Rotovap machine (optional); pH indicator paper;- Laboratory scale (1-1000 g is suitable);
- Measuring cylinders 1000 mL;
- 1000 mL x3; 2000 mL x3; 5000 mL x3 Beakers;
- Several buckets;
Step 1. 3-Methyl-4-phenyl-3-buten-2-one synthesis (cas 1901-26-4).Step 2. 2-Acetoxy-1-phenyl-1-propene (cas 24175-87-9) synthesis.
1. Benzaldehyde 1000 g and methyl ethyl ketone (MEK) 1000 ml are mixed in 5 L flask, stirred and chilled at 0 °C.
2. HCl gas is bubbled slowly through the mixture for a 1.5 h.
3. The solution is stirred for addition 1.5 h at room temperature.
4. Distilled water 2 L is added. The solution is extracted with chloroform (CHCl3) 800 ml x2, then the extract is washed with sodium bicarbonate solution (NaHCO3) to neutral pH and dried over magnesium sulphate (MgSO4).
5. Solvent is evaporated under vacuum and 3-methyl-4-phenyl-3-buten-2-one (cas 1901-26-4) is distilled under vacuum (b.p. 269.6±9.0 °C at 760 mm Hg). Reaction yield is 1000 g.
1. 3-Methyl-4-phenyl-3-buten-2-one (cas 1901-26-4) 1 kg from Step 1, glacial acetic acid 10 L and hydrogen peroxide (H2O2) 1300 g 50 % are poured into a 25-30 L batch reactor with reflux condenser, stirred and at 55 °C for 23 h.
2. Next, distilled water 10 L is added.
3. The reaction mixture is extracted with chloroform 5 L and dried over magnesium sulphate (Na2SO4).
4. Solvent is evaporated under vacuum. 2-Acetoxy-1-phenyl-1-propene (cas 24175-87-9) yield is 800 g.
Step 3. 1-Phenyl-2-propanone (P2P; cas 103-79-7).
1. 2-Acetoxy-1-phenyl-1-propene (cas 24175-87-9) 800 g from Step 2 and sodium hydroxide (NaOH) 600 g in distilled water 2500 ml is stirred at 50 °C for 12 h in 10 L flask with reflux condenser.
2. Reaction solution is extracted with chloroform 1000 ml, dried over magnesium sulphate (Na2SO4) and the solvent is evaporated under vacuum. 1-Phenyl-2-propanone yield is 650 g.
Our team brings together the best specialists from different fields.
We are ready to share our experience, discuss difficult issues and find new solutions.
Connect notifications to always stay in touch with the forum!