cosmo - 24-9-2011 at 07:59
Hey there,
I had a quick question about the synthesis of halogenated Grignard reagents. Suppose I took some 1-bromo-4-fluorobenzene, or 1-chloro-4-fluorobenzene.
Would the reaction between one of these and Mg turnings in ether with a small amount of I2 as a catalyst to get things going proceed as I'm thinking
it would yielding 4-fluorophenyl magnesium bromide (or 4-fluorophenyl magnesium chloride), or would something else happen? I was of the understanding
that fluorine does not like to participate in the Grignard... bromine and chlorine only.
Am I right in saying this, or am I way off base here? Any help much appreciated. Thanks.
Picric-A - 24-9-2011 at 10:35
The reaction would proceed with the bette leaving group (ie, I>Br>Cl>F). You would have to use stoichiometric amounts of Mg though to ensure
that the other halogen isnt touched.
Generally RMgF grignards are petty hard to make and s you would struggle to make it b accident. even RMgCl can be a challenge to make ( chlorobenzene
is hard to react with Mg)
cosmo - 1-10-2011 at 15:45
Very helpful, thanks!