Always_Victory
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Posts: 2
Registered: 20-4-2007
Location: India
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Regarding Dye Synthesis
I am a chemical engineering student from india. Recently i am working on the synthesis
of Solvent yellow-2 ( Aniline -----> N,N dimethylAniline).
I start with aniline diazotisation as usual and then add it to the hydrochloride of DMA and raise the pH with the sodium acetate.
My observation is when i rise the pH to 4-4.5 the aniline diazo stays heavy positive on spot test cutting with H acid soln.
i have stirred the above content for more than 8 hours at 5 deg C.
I have also tried using sodium carbonate, mixing DMA soln in acetic acid to Aniline diazo etc.
But i havent been able to successfully complete coupling and get bright powder.
where am i going wrong ?
i shall be really thankful for help.
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Sauron
International Hazard
Posts: 5351
Registered: 22-12-2006
Location: Barad-Dur, Mordor
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Whose procedure for this classical diazo coupling are you attempting to replicate?
Did you search the lit. to see some variations on conditions?
If not that may be helpful.
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Always_Victory
Harmless
Posts: 2
Registered: 20-4-2007
Location: India
Member Is Offline
Mood: No Mood
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i am not replicating any procedure since i have none. Also
in the C.I.Book i have there is no US or any country patent
number mentioned so i guess its not patented.
BIOS Report number are given which i cant find anywhere.
I am just utilizing my theoretical knowledge and applying
it on practical basis.
the problem is if i keep on stirring the mixture the aniline
diazo will decompose at certain stage. assuming 20% diazo
gets decompose then DMA will be left unreacted. and the
Powder appearance will suffer.
i wanted to know at which pH the reaction goes to completion?
and also the pH rise should be done with sodium acetate,
sodium carbonate,calcium carbonate,caustic soda?
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