Sciencemadness Discussion Board - Synthesis of Tartrazine and Allura Red AC

Synthesis of Tartrazine and Allura Red AC

Nernst - 4-10-2008 at 15:19

Hello,

as a short member but long viewer of this genious forum, I'm pretty sure I'm finaly gonna get my answers.

For a school project I'm looking for 2 synthesis. I've searched freepatens & orgsyn already, but with no luck.

So, now I'm here with the big guys. Could someone provide me the synthesis of tartrazine &Allura REd AC?

Tartrazine (E102):

Allura Red AC (E129):
200px-Allura_Red_AC.png - 12kB

ps, Sorry for my bad english, normaly I speak dutch.
ps2: Jor or Woelen, do you guys know what's going on with our chemieforum.nl?

Edit by Texium: changed title for clarity/searchability

[Edited on 5-15-2018 by Texium (zts16)]

Jor - 5-10-2008 at 02:48

Nernst,

According to woelen, the chemieforum is now 5 years old, and probably the admins have forgotten to pay the 'bill' for the domain. Probably they will pay the following days, bringing the site back online. If they don't within a month, we might have a problem! Then it would be possible for anyone to take over the domain www.chemieforum.nl!

Nernst - 5-10-2008 at 06:14

Oh, they haven't payed their bill. I've read on the site that the site was going to another server...

Now, for the synthesisis. Does anyone have a suggestion where to look?

Klute - 5-10-2008 at 06:25

EIDt: Got ya!

Quote:

"FD&C Yellow N° 5 (Tartrazine, color index N° 19140) is a monoazo dye having pyrazoline ring structure. It is synthesized by condensing phenylhydrazine-p-sulfonic acid with oxalacetic ester. This reaction product is then coupled with diazotized sulfanilic acid. The resulting ester is then hydrolyzed with sodium hydroxide. Alternatively, tartrazine can also be synthesized by condensing two moles of phenylhydrazine-p-sulfonic acid with 1 mole of dihydroxytartaric acid. FD&C Yellow N° 5 is an orange yellow powder. It is readily soluble in water, yielding golden yellow solutions."

From the Handbook of Food toxicity.

Looks more simple than what I would have though! I guess you need to wok your way to phenylhydrazine-p-sulfonic acid.. Which I think can be made my reacting diazotized p-sulfanilic acid with sodium sulfite.

Quote:

"FD&C Red N° 4, (Rouge Ponceau SX, color index N° 14700) was approved for food use in 1929. This monoazo dye is synthesized by coupling one mole each of diazotized 1-amino-2,4-dimethylbenzene-sulfonic acid and 1-naphtol-4-sulfonic acid. A red-colored powder, it ios readily soluble in water, yielding orange-red solutions."

Food Additive Toxicology

PS: you should look in the site library at the dye chemistry books availble. I'm sure you will find further info over there, especially on the preparation of the precursors an general process. There also lots of info in the google books!

[Edited on 5-10-2008 by Klute]

Nernst - 5-10-2008 at 10:50

Klute, you're the best! I think I'm gonna have a nice coffee and read, read, read....

Klute - 6-10-2008 at 12:46

Glad I could help! If you perform the synthesisfor your project, please report your results back here!

bfesser - 6-10-2008 at 13:29

Please, take pictures too!

Nernst - 7-10-2008 at 11:11

I would love to report my results en post the procedure with pictures but I'm stuck with finding the synthesis.

The only thing I can find is:

Tartrazine production involves two stages: (1) the condensation of phenylhydrazine p-sulfonic acid with sodium ethyl oxalacetate and (2) coupling the product with diazotized sulfanilic acid.”

Stage 1:

By nernst

Stage 2:
Production of the diazotized sulfanilic acid.

By nernst

Tartrazine is produced by the reaction of the condensation product with the diazotized sulfanilic acid:

By nernst
This reaction is based on the methylene reactivity of the pyrazolone ring. Reactivity is observed because of the position of methylene between two carbonyl groups in 1-(p-sulfophenyl) pyrazolone-3-carboxylic acid compound.

[bewerken aan 7-10-2008 door Nernst]

Klute - 7-10-2008 at 14:24

Well, you have it, no?

The reaction is detailed on page 265 of this book:
http://www.sciencemadness.org/library/books/fundamental_proc...

I urge you to read this book! And the others on thsi subject in the Sciencemadness Library! You have all the preapration of most of the precursors in there, and the reaction conditions for the condensations.

Sulfanilic is an cheap commercial product, or can be made from aniline by basic reactions. The hydrazine is formed by reacting the diazotized aniline with sodium sulfite (p. 128 of the book cite dabove):

Ethyl oxalacetate can be prepared by a variety of methods (although it can be availble commercialy):
-Claisen between diethyl oxalate and ethyl acetate:
http://www.freepatentsonline.com/4902819.html
http://www.pat2pdf.org/patents/pat1948201.pdf

-acylating acetoacetate with mono ethyl oxalyl chloride (EtOOC-COCl) or a similar ester, selectively de-acetylate, then hydrolyzing the oxalate ester:
http://www.orgsyn.org/orgsyn/pdfs/CV3P0379.pdf
http://www.orgsyn.org/orgsyn/pdfs/CV2P0266.pdf
http://www.orgsyn.org/orgsyn/pdfs/CV4P0415.pdf

-acylating diethyl malonate with the same ester, and hydrolyzing the oxalate ester after mono-decarboxylation:
http://www.orgsyn.org/orgsyn/pdfs/CV4P0285.pdf

All the rest in described in the Dye books.

the reactivity of the emthylen group issimply du to it being in alpha position of the "hydrazine amide", not the the carboxylate which is two carbons away.

I think that's all I can do for you, can't do the reactions myself

. the info is just right one the first page on this site