Now I have complete the synthesis of 1-pyrimidine, 6-bromopyrene. Next step, I want to realize the sulfonation by replacing the bromine atom with sulfonyl.
I wonder whether I can try SNAr2 method, using Na2SO3 to generate -SO3H, to replace the Br. If it can't work, are there any other method (not only the substitution reaction) to realize the sulfonation?
As you mentioned It will bimolecular aromatic substitution reaction (SN2Ar). So the concen. of both reagent and substrate will decide rate of reaction. If the aromatic ring i.e pyrene have electron withdrawing gp (at ortho or para to Br), the reaction will be easier if not then have to use metal catalyst.
1. Reagent- Sodium Bisulfite (NaHSO₃)
Nucleophile: The bisulfite anion (HSO₃⁻) or sulfite (SO₃²⁻, formed in basic conditions) acts as the nucleophile.
Product: Forms Ar–SO₃Na, which can be protonated to Ar–SO₃H.
Conditions- Basic
Solvent: must be DMF or DMSO as SN2Ar (but if reaction is reversible (SN1Ar) depends upon type of reagent, yield will be lower then use water.)
2. Reagent: Potassium Sulfite (K₂SO₃) Nucleophile: Similar to Na₂SO₃, provides the SO₃²⁻ anion.
Product: Yields Ar–SO₃K, which can be protonated to Ar–SO₃H
Solvent: DMF, or DMSO.
Temperature: 60–120°C.
The problem with proposed idea is two-fold: firstly, aryl-bromine bond needs to be dissociated; secondly, sulphite must be forced to react with sulphur, not with oxygen. First can happen with metal-halogen reactions, like Ullmann-type reactions with copper(I). Second is tricky, as most solvents would promote latter. You probably will have more success subtituting bromine for thiol and then oxidizing it with sodium hypochlorite.
- Badges
- Science topic