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