Vanillin bromination failure....

[Antoncho]

32 g vanillin (bought in a grocery store) were rextyllised from hot water filtered and pressed dry. About 30g of slightly moist vanillin was obtained. The mp wasn't tested but it showed all proper signs of melting in hot water, forming a clear bottom layer.

Then a procedure identical to that performed by Uemura in

Post 297806

(uemura: "How to prepare hydroxyvanillin", Methods Discourse) was carried out, xcept on a 1/2 scale and at 15 C (instead of 20 C). H2O2 was old, so to make sure all KBr reacted, an additional <10mls was added. Some real tiny bubbles began to appear, so probably H2O2 wasn't bad.
The mixtr turned yellow-brownish during the addition, but NO Br-vanillin precipitation was apparent at any time.

The rxn was flooded w/icewater and the tiny crop of xtals was filtered, dryed and found to weigh ~4g. They don't melt at 100 C (good sign).

Merde .


Any ideas? Experiences? Help!


Antoncho

[tiresias3]

Grocery store vanillin is generally cut.  Invest in some USP certified vanillin powder next time and see if that helps any.

[GC_MS]

Commercial vanillin can contain some "impurities" (such as (iso)eugenol), and can be cut with other substances. Vanillin powder can be obtained in 99%+ purity at chem stores. Don't be as stooopid as SWIM and have a taste of the powder... its smell was delicious (if you like vanillin of course) but it was too concentrated for my stomach   .
-[ A Friend With W33D Is A Friend Indeed ]-

[tiresias3]

I concur with the above statement.  I added a tablespoon of pure vanillin powder to some 2% milk and sugar expecting to get some tasty vanilla milk but ending up having to pour most of it down the drain which is truly a shame really.

[foxy2]

the vanilla powder typically sold in the grocery store is about 2-5% vanillin and fillers
Those who give up essential liberties for temporary safety deserve neither liberty nor safety

[Antoncho]

I assume, the main cutter would bee sugar - actually, that's what i attempted to get rid of when crystallizing it from water (actually, not all of it dissolved but anyway).

And well did the bromine go?

Ahhh, it's so confusing and embarassing - such an elementary thing and i can't do it


Actually, a iodination/hydroxylation was attempted on the same vanillin bee4 bromination - and the result was

a) Only about half of theoretical iodine reacted

b) There was lots of tar in hydroxylation stage

c) Xtraction w/CHCl3/MeOH (as described in the patent) gave a very small yield of impure xtals that immediately melted in hot water.


Obviously, smth must bee wrong w/the vanillin SWIM used - but is there a way to get rid of the impurities? A min qtty of chem pure vanillin would bee 1 kg and that'd bee an outrageous amt of money for SWIM.





Antoncho

P.S. I must take its mp, definitely. What if it turns out to bee correct?    

[Chromic]

In SWIC's experience with bromination, perhaps you needed to use an excess of H2SO4?

Btw, I second the question of purity. What about vacuum distillation of the vanillin?

[GC_MS]

SWIM just took a look at some kitchen vanillin, and it indeed mentions sugar as cutting ingredient. SWIM thinks you might have brominated/iodinated some of your sugar. You might want to try some colour test for sugar identification. There are some simple test at

http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA5/MAIN/WORDS/WORDS01.HTM

- but be carefull with your interpretation! Some of the test are based on the presence of aldehyde groups in sugars, and your vanillin has an aldehyde group as well.
You say "there was lots of tar"... did you use H₂SO₄? If you did, SWIM is almost sure the tar is "carbonized" sugar. Sulfuric acid decomposes sugar and leaves some weird stinking shit.
-[ A Friend With W33D Is A Friend Indeed ]-

[tiresias3]

If a half pound of USP certified 98% pure vanillin powder costs less than 30 USD including shipping and handling delivered to your door, I fail to see why you shouldn't be able to afford it, especially considering the price of glassware, heating mantles, digital scales, etc. nowadays.

The bottom line is that if you don't use the very finest, most pure raw materials available in your syntheses, your product will be crap.  It's sort of like trying to synth lsd from morning glory seed extracts instead of pharmaceutical grade ergotamine tartrate.  It's not gonna happen.

[Osmium]

> I fail to see why you shouldn't be able to afford it,

For some bees $30 is a whole week's pay.
I'm not fat just horizontally disproportionate.

[foxy2]

Thats more than I made all of last year  

Looking to sell body for precurors  
Those who give up essential liberties for temporary safety deserve neither liberty nor safety