Benzaldehyde and MEK - TwoDogs Method

[lalalander]

I was performing the aldol condensation between benzaldehyde and MEK by heating with aqueous HCl, then washing to neutral and vacuum distilling.

However, I cannot isolate the aldol product by vacuum distillation because my vacuum pump is broken.

It is easy to make sure that things are going well when I get a black oily liquid when heating, but because my reflux condenser is not efficient enough, HCl gas escapes.

So I stir it with aqueous HCl first at 0 degrees for 6 hours and then at room temperature for 24 hours and wait for the mixture to darken in color. But it doesn't happen. It's only a deep red color.

I cannot crystallize the resulting organic layer in any way.

Can anyone help?

Thanks.

 

[The-Hive]

An old fridge compressor are good for vacuum. You can source them from any junkyard.

 

[lamer]

2 köpek methodu he

 

[Osmosis Vanderwaal]

I think for under $15 i could build a venturi type asperator

 

[Field7]

Steam distillation

 

[lalalander]

Can unsaturated ketone be steam distilled? I didn't know. Thanks.

 

[lamer]

rojin napıo

 

[BayHyde]

Hello Bay Lalalander,





As I mentioned before, a good vacuum can sometimes be everything. Could you share the vacuum level (in mmHg) you used during the vacuum distillation, along with your observations on the mixture and vapor temperatures? Without this data, assessing the progress of your process might be quite challenging. Additionally, if you provide more detailed information, such as previous mixture ratios, photos of the reaction at the start and end, or visual progression, our ability to assist you will significantly improve.





By the way, a refrigerator compressor can certainly be a creative solution—but only temporarily. Once you’ve locked up the third one, you’ll likely gain a much deeper appreciation for the phrase, "a good vacuum is everything." If you're currently using a refrigerator compressor, chances are you've already retired your first one.

 

[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.

I no longer have any problem with aldol condensation step.

Here is a picture showing the upper organic layer, the lower aqueous layer, and the crystals obtained after freezing, before washing with cold methanol, for anyone is interested;

 

[BayHyde]

Congratulations, by. Lalalander!


I’m really happy to see your progress and that you’re finally able to send a photo! I hope beautiful days are approaching for you as well. I couldn’t assist, so I guess there’s no "thank you" for me, right? Well, that’s how the world works...


Anyway, apply recrystallization once or multiple times to make them harder, drier, and purer; this will make it much easier to track color changes related to oxidation. Always separate a bit of the hardest and largest pure crystals, as they will help with faster crystal formation in future productions by serving as seed and precursor crystals. Distill the remaining solution with methanol or ethanol, then heat the residue to 150°C, store it, and collect it.


Once your vacuum distillation process begins, distill again to increase your yield; hey, what do they say, this could be half the rent!

 

[lalalander]

I'm grateful to everyone who approaches my problems with the intention of helping, whether it benefits me or not. I'm just very tired. I'm sorry if my behavior was hurtful to you.

Thanks.

 

[BayHyde]

Kardeşim Sen buz kullanmadigina eminmisin dicem yine alıncan yani ben kullanmama rağmen hatirliyosam sen ya hatırlamıyon beni yada hiç sallamamissin dediklerimi daha önce sentezledim kardeşim şimdide sentezliye biliyorum hatta dev bir labta inşa ediliyor verim istediğim seviyeye çektim maliyet tamamen düşürmek için 1 numaralı kural nedir