Difluoromethylation of unsaturated compounds
A reagent for carrying out a difluoromethylation reaction of unsaturated compounds and ring-nitrogen-containing aromatic compounds, a zinc difluoro-methanesulfinate, as well as a method for making the reagent and a method for its use are disclosed.
1. Zinc difluoromethanesulfinate.
2. The zinc difluoromethanesulfinate according to claim 1 present as a hydrate.
3. The zinc difluoromethanesulfinate according to claim 2 , wherein said hydrate is a trihydrate.
4. A method of preparing the zinc difluoromethanesulfinate of claim 1 that comprises the steps of:
a) admixing HCF 2 SO 2 CI in a vessel with an agitated admixture of zinc particles and water cooled to about zero degrees C. to form a reaction mixture, moles of said zinc particles being in excess over the moles of HCF 2 SO 2 CI admixed;
b) permitting said reaction mixture to warm to about ambient room temperature;
c) separating unreacted zinc powder from the remaining reaction mixture; and
d) removing the water to provide the zinc difluoromethanesulfinate.
5. The method according to claim 4 , wherein the zinc difluoromethanesulfinate formed is a hydrate.
6. The method according to claim 4 , wherein said zinc difluoromethanesulfinate is recovered.
7. The method according to claim 4 , wherein said vessel is a pressure vessel that is sealed after admixture of HCF 2 SO 2 CI is complete, and while the reaction mixture is permitted to warm to about ambient room temperature.
8. The method according to claim 4 , wherein said reaction mixture is agitated until the HCF 2 SO 2 CI has reacted.
9. The method according to claim 4 , wherein the molar ratio of zinc to HCF 2 SO 2 CI is about 2:1 to about 10:1.
10. The method according to claim 4 , wherein said zinc particles are sized to pass through sieve of about 1250 to about 2500 Tyler mesh through about 10 to about 18 Tyler mesh.