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Topic: Wurtz Reaction Problem  (Read 2872 times)

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Offline theTheorist

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Wurtz Reaction Problem
« on: November 18, 2015, 09:16:13 AM »
Hey Guys!

I stumbled across a rather simple, yet confusing (to me) problem on the Wurtz reaction.

If I have two compounds (1 mol each) -> 1) C1CC(Cl)CCC1Br and 2) ClCCCCCCBr and I react both with Na (2 moles) in Dry Ether, then which one is more likely/ more easily going to undergo Wurtz reaction?


Thanks a lot!
Cheers,

Offline orgopete

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Re: Wurtz Reaction Problem
« Reply #1 on: November 19, 2015, 09:41:06 AM »
I also could find the wording confusing, but I think the intent of the problem is more like, "Which reaction will lead to the product in higher yield?" In that case, draw the products and compare them. Which do you think is higher in energy (more strain)? I think the reaction rates though would be similar and would depend on the contact rate with the sodium.
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Offline theTheorist

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Re: Wurtz Reaction Problem
« Reply #2 on: November 20, 2015, 03:11:36 AM »
@orgopete, but don't you think the cyclic ring (being cyclic already) (as you said about the strain) will not compose of a major portion of the products?

Offline orgopete

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Re: Wurtz Reaction Problem
« Reply #3 on: November 20, 2015, 10:34:48 AM »
I think there are two issues in play, stereoelectronics of the reaction and the strain of the products. While the reaction centers of the two groups are closer in the cyclohexane, I don't know this will increase the rate of bond formation as the ring is also stereochemically limited while the alicyclic one is not. For example, the cyclohexane may require a boat conformation. Further, it may prefer a cisoid configuration. The alicyclic reactant has more degrees of freedom and can adopt any conformation needed for ring closure.

I also think that just by virtue of forming a higher energy product, there should be a toll on the overall rates and/or yield. If you put both reactants in with sodium, I'm thinking the cyclohexane forms faster.

Since you stumbled upon this problem, can you also tell us the answer?
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

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