[farkhanda]

HELP NEEDED IMMEDIATELY!!!

Hi iam a student of chemistry working on a research report, I MUST SUBMIT MY RESEARCH REPORT BY THE END OF JUNE. I am working on the synthesis of 2,4(1H,3H)-Pyrimidinedione commonly known as uracil (a nucleic acid base of RNA).

I am currently using a method involving condensation reaction between urea and maleic acid in polyphosphoric acid. The thing is, every time i start the reaction the Polyphosphoric acid turns from colorless to dark brown, after decolorization with charcoal i am left only with the colorless filtrate with no sign of any solid product in it. I HAVE NO IDEA HOW TO GET URACIL IN SOLID FORM OUT OF THAT REACTION MIXTURE. Ihave tried cooling even freezing to ppt out uracil, i have even tried solvent extraction but no solvent is good enough to remove uracil (if any) from aq. layer.

PLEASE HELP ME....
1. Does any one know how to prepare uracil from urea and maleic acid?
2. Can anyone figure out what i am doing wrong?
3. Is it normal for polyphosphoric acid to turn dark brown after heating? if yes why?
4. Any other method to prepare uracil?

[hmx9123]

Why don't you evaporate the solvent and then see what you have left first?  If you can't get anything to crystallize out, chances are your solutions are too dilute.  Then you need to find solubilities of the chemicals that you're working with.  Figure out what will dissolve your product and not your starting materials or vice versa.  You should be able to find that in the Merck index with little to no problem.