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mississippichem

"di-Grignards

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Anyone know if reactions of this type are possible? I know organo-maganesium compounds often form nasty conglomerates. If anything prevents this reaction from working, it probably has to do with the complex Shlenck equillibrium.

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That specific grignard cannot be prepared. The reaction instead proceeds by the formation of ethylene and 1 equivalent of magnesium bromide. In fact 1,2-dibromoethane is a common initiator for sluggish grignards because the product removes itself from the reaction mix as visible bubbles.

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Digrignards arre fairly difficult to make so I'm not sure if that is even possible. Typically, digrignards react intre or intramolecularly once the first grignard has formed

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Thanks for your answers.

 

That specific grignard cannot be prepared. The reaction instead proceeds by the formation of ethylene and 1 equivalent of magnesium bromide. In fact 1,2-dibromoethane is a common initiator for sluggish grignards because the product removes itself from the reaction mix as visible bubbles.

Yesterday 5:29 PM

 

What if the reaction where to happen closing to a larger ring, perhaps to a seven or nine membered ring (eight membered rings are a nightmare for some reason). This would involve a less volatile substrate, would this still lead to those pesky, thermodynamic elimination products?

 

Digrignards arre fairly difficult to make so I'm not sure if that is even possible. Typically, digrignards react intre or intramolecularly once the first grignard has formed

 

what if pi-bonds (not alkynyl; wouldn't allow from ring closing due to intense angle strain) were introduced to limit C-C bond rotation preventing the intramolecular reaction?

 

These are just thoughts. I guess I just subconciously want to see this reaction work. It would be almost too good to be true wouldn't it?:eyebrow:

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