SESHU - 29-3-2016 at 17:44
Hi
I want to make 2-acetyl thiophene from thiophene and acetic anhydride in presence of phophoric acid. i am getting the product (2-acetyl thiophene
with 99% purity and 0.5% 3-acetyl thiophene content) after distillation. it is forming ~ 1.0% in reaction it self, can any one help me to minimize
the 3-acetyl thiophene in reaction it self/ purification method to get the 3-acetyl thiophene content below 0.2%.
Thanks
clearly_not_atara - 29-3-2016 at 23:46
Maybe 2-acetylthiophene acts as a bidentate ligand for some cation? Producing the complex could get you your separation.
Boffis - 31-3-2016 at 05:45
@SESHU, its very difficult to offer any advise if you don't give us a reference to the procedure so we can examine it. However, from my experience
(fairly limited) of thiophene chemistry is that if you are only getting 1% of less of the 3 isomer that is excellant. If the acetyl thiophene is an
intermediate itself you are probably better just to repeatedly recrystallise the final product to remove the isomeric compound. Trying to reduce the
production of the 3 isomer further looks like a lost cause to me.
Incidently I eventually purchased some 2-acetylthiophene, the manufacturer is Aldrich and the product claims to be a minimum of 99% but even so that
leaves scope for as much as 1% of the 3 isomer. What purpose exactly requires such a high purity if you don't mind me asking?