Vanillin ethylation w/K-ethylsulfate & microwaves

[Antoncho]

Here's what happened in somebee's kitchen yesterday...



The following was intimately ground/mixed together:

- 5g vanillin
- 3g NaHCO₃
- 10g KEtSO4 (containing ~65% KEtSO4 as titrated w/CaSO4 and 0.07moles of K₂CO₃/KHCO₃)


The powders' mix was placed on the very edge of SWIM's domestic microwave's turntable (to minimize intensity of heating - SWIM's microwave is of 'pulsing' kind) and the oven turned on.

As soon as the inside mixtr melts and evolution of CO2 (accompanied by appearance of heavy fumes inside the flask), heating was stopped and the flask cooled under running water.

This sequence was repeated 4 times - SWIM tried to avoid charring as much as possible, but wasn't totally successful.


The rxn mass was dissolved in 150mls hot water, some aq NaOH was added and the mixtr was xtracted w/DCM 4x30mls, washed 1st w/10% NaOH, then 2x w/water, dried, DCM removed and the xtallized brown residue weighed.

2,8g (47%)

No smell of vanillin, mp of impure xtals definitely above 51 Ñ (lit. 71 Ñ)

Rextallization or bisulfite purification wasn't attempted due to the small qtties. Later....





Next time SWIM is going to try adding more ethylsulfate as the rxn proceeds. Presence of unreacted vanillin in the post-rxn mixtr was evident, so....

The main obstacle would bee to insure proper mixing of the newly added KEtSO4.

A side note: it appears that KEtSO₄ is quite unstable, much more than we thought bee4. It decomposes appreciably even on boiling off EtOH (from post-neutralization KOH/HEtSO4 mixture). Probably, a yet larger proportion of it decomposes upon evaporation of residual water. SWIM tried leaving the shit to air-dry (not even distilling off any alcohol) - and 67% was what he got.




Antoncho

[Antoncho]

... doesn't anyone have anything to say? i mean, no one even suspected it was possible bee4...

I guess i chose a wrong subject line...

[GC_MS]

Hey! No replies doesn't mean your post stinks Anton  

As a matter of fact, you reminded me of the fact that I still have to bring a homage to Leminger, and synthesize the amphetamine analogue of MEPEA.

[Mountain_Girl]

Antoncho,

This is the sound of two virtual hands clapping : "       "


Good work.

For bees who don't live in a vacuum or even near one,
who would have trouble synthing diethyl sulfate,
this is a useful alternative for ethylation.

Questions:
* Why you add NaOH before xtraction with DCM ?
* Don't understand how you titrated with '0.07 moles of K₂CO₃/KHCO₃'.
  Also, K₂CO₃ is frequently mentioned in synths. Does one assume it is actually K₂CO₃.3/2H ₂O, unless specified as anhydrous ?
* I assume you, sorry SWIA, are simply testing the method on vanillin. Or does SWIA have plans for the MEPEA amphetamine like GC_MS ?

[Antoncho]

2 GC_MS: see, saying smth like this always helps!      _{(hey, i'm j/k)}

My 'passport' name really is Anton but i somehow never fully identified myself with it (). I do fully self-identify with "Antoncho" when it comes to any non-ordinary activity of mine. So don't call me like that

In ordinary life i get by without any name


2 M_G:

This is the sound of two virtual hands clapping : "       "

Thank you, amigo

For bees who don't live in a vacuum or even near one,
who would have trouble synthing diethyl sulfate,
this is a useful alternative for ethylation.


Actually, the most important point in this research would bee (if it was more successful than it is now, that is ) to provide an environmentally friendly way of alkylation.

Metal alkylsulfates are the only non-carcinogenic cmpd's of them all. They are ideal for a kitchen chemist. All that is left is to make them work

Why you add NaOH before xtraction with DCM ?

To remove the unreacted vanillin. Actually, if water/alkali washes aren't meticulous enough, there remains quite a smell of vanillin.

Don't understand how you titrated with '0.07 moles of K2CO3/KHCO3'

With H₂SO₄ of a known concentration (21.73% w/v in SWIM's case)

But of course, i made a mistake: it was 0.007moles per 5g of my 'ethylsulfate'.


Does one assume it is actually K2CO3.3/2H 2O, unless specified as anhydrous ?


Anhydrous.

are simply testing the method on vanillin. Or does SWIA have plans for the MEPEA amphetamine like GC_MS ?


Both, naturally



Antoncho

[Antoncho]

This xperiment was repeated, this time using:

- 4,3g vanillin
- 14g of the above KEtSO4
- 2g K₂CO₃

That is, the idea was to use more KEtSO4. K2CO3 was subst'd for baking soda to decrease water content of the rxn.

Intermittent cooling was omitted - instead the chemist just shifted the flask from side to side to ensure complete and uniform 'frying' of the contents (which is - the uniformity, that is - very hard to achieve in his MW). The mixtr beecame brown at the end, total heating time was maybee ~4mins.

After working the rxn up as stated above there was obtained 3,3g of impure aldehyde (65%).




So, AS YOU CAN SEE, the yield-limiting point in the reaction is apparently decomposition of the ethylsulfate.





What we need at the moment is to find out a way to prepare 100% (or close to it) K or Na ethylsulfate. I am pretty certain that this will allow us to get really satisfactory yields.

But its preparation is picky... real picky. You have to carefully titrate everything at every stage. Beecause you must finally arrive at a precisely neutral product. Well, maybee a lil on alkaline side, but not more than that.


Like, KOH always contains some water - you have to titrate it after dissolving in EtOH.

HEtSO₄ is of unknown percentage to begin with - more than that, with time it decomposes standing over Na2SO4 turning into Et2O - so it has to bee titrated every time bee4 neutralization.

Then, after you're done, you have to titrate what you've got to see if everything went OK and there ain't no big xcess of alkali in the mixture (HEtSO4 hydrolyses during neutralization forming H2SO4, which is one proton richer so there's no way to predict the eventual pH).

Finally, after drying you titrate the end product with CaCl₂ to see what you obtained (this can bee estimated from the weight of the dry salt relative to the amt of alkali initially used).


SWIM must admit he never performed this with due scrupulosity (the last time he got caught by the fact that his previously titrated HEtSO4 decomposed on standing) so he can't say with certainty that simply drying out carefully made KEtSO4 won't do fine. He currently thinks it is possible either way and only experiment can tell the truth.




That's it for now.


Antoncho

[Mountain_Girl]

A ~65% yield sounds pretty good to me under kitchen kondishuns.
[I usually work on an expected yield of ~60% of literature values]

You don't seem to be following the procedure at Rhod's [

https://www.thevespiary.org/rhodium/Rhodium/chemistry/nitroalkane.html

] in which the unstable HEtSO₄ is immediately converted into the Ca then Na salt ?

[moo]

Also: would Ca(EtSO₄)₂ be useful at all?

Nice work! This means that i'll have to scan that good article on microwave modification.

[ClearLight]

Most microwave reactions go at 200-400 watts.. the cycle on/off power stuff just pulses the reaction.  Put a 600ml beaker of water in there as well to soak up the excess energy.  If your dealing w/ a large (ie tall) erlynmeyer or other flask, set you microwave on it's back /w the door on the top. You can get a really nice sized flask in that way.. a plastic block can be used if you need to elevate the bottom of the flask off the wall to insure proper mw exposure.

  I imagine you can measure the temp rise in a 500 ml flask full of  water after 1 minute to compute the energy absorption at full power ( usually 1500 watts emitted), and then adjust your water volume accordingly to give you the correct power range for your reaction.