[darkdevil]

Hi there,
I synthesized a polymer using the ATRP method, so one of its ending would have a halogen group attached. I assumed that the halogen ending would be a poor electrophile due to its large molecular weight. So I am think if it is possible for the polymer to undergo Grignard Reaction like the scheme below? So that I can transform the end group to be a reactive nucleophile and couple to other molecules?

Has anyone tried something similar before?

[Hunter2]

The question is, what molecular weight you have and also in which solvent its soluble. Did you tried to solve in THF?

[opsomath]

It's not impossible, as long as your R-group is compatible with the Grignard reagent. It's likely the reaction will be pretty inefficient, though, if you are using solid magnesium.

[darkdevil]

I am going to try this with oligomers first, with 4-10 units.
What else can I use instead of solid Magnesium?

[opsomath]

You can use Rieke metal (still solid, but highly activated) for a boost in activity, or else you can try lithium-halogen exchange (http://www.chem.harvard.edu/groups/myers/handouts/9_Lithium_Halogen.pdf) with two equiv of t-BuLi to convert the halogen into a lithium atom. Note that these two reagents are both very powerful and reactive, and can be hazardous.

What are you trying to do on the endgroup? If you just want some specific group attached there, consider some form of click chemistry, like use sodium azide to convert it to an azide then click on whatever you want.