Benzaldehyde and MEK - TwoDogs Method

[Newbee]

can anybody provide me receipt to it

• lalalander

 

[lalalander]

When 10 grams of Benzaldehyde + 10 grams of MEK and 7 grams of 30.5% aqueous HCl are mixed for 24 hours at room temperature, I obtain an organic layer.

The reaction should be carried out in an inert reactor, and the mouth of the reactor should be sealed with an inert stopper (such as LDPE, Teflon, glass, etc.).

I wash the organic layer with NaHCO3 solution until it is neutral and put it directly into the freezer. No heating. I filter it using a vacuum cleaner motor. This separates the remaining residual Benzaldehyde and MEK. White crystals remains behind.

When I pour -18 degree methanol on it, I obtain completely snow-white crystals. In my last test, I used 50 grams of Benzaldehyde + 50 grams of MEK and 35 grams of 30.5% aqueous HCl. I obtained 46 grams of snow-white crystals.

Methanol must be cooled in the freezer. Otherwise a lot of crystal will dissolve in the washing step.

I also think you can use ice water when washing, but I haven't tried it yet.

 

[LabPsycho]

Try the Oxone. I found this peroxymonosulfate with a different name but haven't tried it... I think it is ready-to-use peracid, and was in some kind of granules or powder when I shook the container..

 

[LabPsycho]

You'll find almost all the interesting stuff at the pool section...haha

 

[lalalander]

I bought DMF and Oxone, but because I don't have a powerful stirrer, the magnetic stirrer stops stirring even with a minimal amount. I have 1.5 weeks of peracetic acid waiting to be used, but I don't see any color change or temperature increase during “oxidation” and the crystals come back after isolation. Can you elaborate a bit on your procedure?

 

[LabPsycho]

I make my own peracetic. It's as easy as to make coffee. Can't you find glacial acetic and 12% or something H2O2? Then make H2SO4 also it is so easy.

 

[lalalander]

I have GAA, 50% H2O2 and H2SO4. All of them are lab grade. But it doesn't work. It reacts vigorously with metals though, but not with the crystals.

 

[LabPsycho]

You'll see the oxidation is happening, when you take it out from your closet, or ..somewhere and look into it with good light, those bubbles are rising fast. Not like boiling but little bit alike. Why you look temperatures or color changes? When you have oxidised the MPB, you take it out (24 h oxidation time), and pour water, and it will change colour from bright "water-like" to light yellow .. messy looking. Then extract those yellow phases, and when you wash those solutions out of acids, you'll get sweet smelling yellow extracts.

 

[LabPsycho]

Try NOT to touch it. It reacts VERY vigorously with your hand.

 

[lalalander]

"Try NOT to touch it. It reacts VERY vigorously with your hand." Too late. Learned the hard way. Are you saying that the crystals that I thought came back are actually acetoxy ester? Because I have never witnessed the acetoxy ester I obtained from the reaction of GAA and perborate to form crystals. Therefore, I thought that what came back were unreacted crystals. Also, the smell is almost the same as the starting material.

 

[LabPsycho]

I would get rid of that peracid. To store those kind of chems is not good, when you don't even use them. I can see that you know the procedure, but you still don't make even sense with your answers. What can I say...

 

[LabPsycho]

No, I am not saying that acetoxyphenylpropene (the ester molecule) is some kind of crystals. It is yellow oil.

 

[lalalander]

Yeah, sorry. I thought you wrote crystals instead of extracts.

 

[lalalander]

What are you using as a solvent? Also, it sounds like you are leaving the oxidation in a closed place without stirring. Is that correct?

 

[LabPsycho]

I extract the product with some non-polar solvent. Yes, that it correct. And always use safety-first protocol. Nitrile- or rubber gloves, gas mask, and safety goggles. Especially with per-acids!

 

[lalalander]

Thanks. What about oxidation solvent? You put the ketone in peracetic acid without solvent?

 

[LabPsycho]

First I make glacial acetic acid / MPB-solution. Then I measure the amount of sodium carbonate, and slowly put the sodium carbonate to the MPB/GAA-solution to basify it. I do this just when the peracetic acid is ready to use. Then I CAREFULLY made the neutralization reaction (acid/base so exotermic), like dropping the basic MPB/acetic acid solution to peracetic acid (in cold water bath). Then when all is done, I stirr the peracid/MPB/acetic-mix a little bit, and put the container in dark storage closet with lid loosely on top, or use rbf and condenser for this (witch I recommend, but both works). When 24 hours has passed, I'm ready to work forward, but never without those gas mask, thick rubber gloves and safety goggles (I want to keep my sight etc..). That is my procedure, so tell me yours so I can help you if I can?

 

[LabPsycho]

Usually the yield is 85-100%. And I use just own made 30% H2O2. If you have 50% H2O2, that it always better and I want to know how you cannot do this step if you say you can do peracetic acid! So tell me you procedure. I want to help here, not judge or be an ass... so don't get me wrong if I don't answer if you don't post your procedure. Please understand this: These reactions are even illegal to plan already, where I live.

 

[lalalander]

I'm using Chromic's buffered peracetic acid route. But without any buffering agent. Because the original procedure from 1936 says that the reaction must be acidic.

 

[LabPsycho]

You said this: Are you saying that the crystals that I thought came back are actually acetoxy ester? Because I have never witnessed the acetoxy ester I obtained from the reaction of GAA and perborate to form crystals. Therefore, I thought that what came back were unreacted crystals. Also, the smell is almost the same as the starting material.

Ok, so where have you witnessed acetoxy ester, if you haven't even oxidized it? From TV?
And if you did it with perborate route, just use that. Enough said.

 

[lalalander]

The problem is that in the perborate method, it has to be synthesized because perborate is not commercially available in my country. And you need large excess GAA. GAA is expensive and peracetic acid prepared in advance saves a lot of money and I use DCM as solvent. It is very cheap. In a procedure where I have to synthesize everything myself, 35% yield is not attractive. Either I need to make it cheaper or it's too tiring to go to so much trouble for 35%.

 

[lalalander]

The DMF and Oxone route is successful. But the stirrer is still a problem for me. I can't work with more than 15 grams of ketone because of the weak stirrer. (I get around 9 mL steam distilled P2P from 15 grams of ketone.) I will try it as you did, let it mix a bit and then leave it in a dark place for 24 hours without mixing it any more.