Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: AlphaScent on July 09, 2019, 03:57:43 PM
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Hey All,
Does anyone have any experience with adding Grignards to propylene oxide in good yields? It seems a lot of the older literature shows that the alcohol is made as a minor product to the bromohydrin. Also there is possible polymerization that can occur. Adding dioxane I think may help with producing the dialkyl Mg species and pushing the Schlenk equilibrium to the right. This all may be a decent idea but let me know if you have any practical experience doing this type of work.
A reaction would be like 1-octylMgBr reacting with propylene oxide.
Thank you in advance!
Cheer!
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Best to make the dialkyl magnesium cuprate and make BF3-complex, then mix with the epoxide. I think its simmilar to dialkyl lithium cuprates. I have reacted grignard with secondary epoxide with good yield so I am not sure if cuprate is neccesary. HMPA would probably speeed things up. In your case the epoxide is not sterically hindered so maybe its very easy.
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Addition of Grignard reagents to ethylene oxide, is described in various editions of the Vogel’s Textbook of Practical Organic Chemistry (Chapter: Aliphatic alcohols). For example, in the 5th Edition, this corresponds to the pages 535-537. However, the obtained yields are rather moderate (50-70%).
Anyway and in the case of propylene oxide, you will get a mixture of alcohols and the secondary alcohol will probably be the major product.
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Here is the reaction I made, dont remember the yield:
https://pubs.acs.org/doi/10.1021/jo00009a012
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rolnor,
You saw no Payne rearrangement?
I have a reference that adds an aliphatic Grignard to propylene oxide utilizing catalytic CuI. They do report minor Wurtz products which is kind of annoying. I am going to try it because it is an easy reaction.
We shall see.
Cheers!