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Topic: How do you turn propylmagnesium bromide into propane?  (Read 6672 times)

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Offline odicon

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How do you turn propylmagnesium bromide into propane?
« on: March 30, 2010, 07:27:10 AM »
How do you turn propylmagnesium bromide into normal propane?
CH3CH2CH2MgBr ---------> CH3CH2CH3

What reagent would I need?

Thanks.

Offline tmartin

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Re: How do you turn propylmagnesium bromide into propane?
« Reply #1 on: March 30, 2010, 07:30:20 AM »
Well, for starters, what is propyl magnesium bromide?  An acid? A base?  Electrophile? (etc...etc.)  Also, what bond do you need to form in order to make propane from the grignard? 

Offline haktar

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Re: How do you turn propylmagnesium bromide into propane?
« Reply #2 on: March 30, 2010, 07:43:21 AM »
Propyl magnesium bromide can (loosely) be thought of as Propyl(-) and MgBr(+)

It is therefore a strong nucleophile (Pr-) and a very strong base. Think of how stable propane is, so how much it wants that proton back! In other words, how difficult is it to deprotonate propane? Very! pKa about 30ish! So it's vey basic.

So if you put propyl magnesium bromide in a proton rich environment (An alcohol, a carboxylic acid, water...) what will happen?

Offline Schrödinger

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Re: How do you turn propylmagnesium bromide into propane?
« Reply #3 on: March 30, 2010, 09:12:44 AM »
So if you put propyl magnesium bromide in a proton rich environment (An alcohol, a carboxylic acid, water...) what will happen?
Actually, you don't need a proton 'rich' environment. Anything that's more acidic than propane should suffice. Even NH3, which is regarded as a Lewis base, is fine.
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Offline odicon

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Re: How do you turn propylmagnesium bromide into propane?
« Reply #4 on: March 30, 2010, 12:44:11 PM »
Thanks for the insight!!

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