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Topic: question about mechanism in chemistry  (Read 1229 times)

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Offline The apprentice

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question about mechanism in chemistry
« on: December 15, 2021, 02:44:40 PM »
Good morning everyone, I'm studying chemistry and I came across the following problem. If possible, someone could teach me how to solve it (step by step)

Starting from hex-3-ene how should I make a Br2 addition mechanism?

Offline Babcock_Hall

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Re: question about mechanism in chemistry
« Reply #1 on: December 15, 2021, 03:09:53 PM »
What are your initial thoughts?  For example, are there intermediates? 

Offline The apprentice

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Re: question about mechanism in chemistry
« Reply #2 on: December 15, 2021, 03:30:15 PM »
What are your initial thoughts?  For example, are there intermediates?


well I first compare the type of Br-Br bond, then I broke the double bond.then I put both in each carbon

Offline Babcock_Hall

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Re: question about mechanism in chemistry
« Reply #3 on: December 15, 2021, 04:01:25 PM »
When you broke the double bond, what intermediate did you obtain?

Offline The apprentice

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Re: question about mechanism in chemistry
« Reply #4 on: December 15, 2021, 06:31:25 PM »
When you broke the double bond, what intermediate did you obtain?



well I'll break the double bond to put the two BR in the bond but I'm not sure if it's right or what I'm doing

sorry for the bad english

Offline Babcock_Hall

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Re: question about mechanism in chemistry
« Reply #5 on: December 15, 2021, 07:13:08 PM »
It sounds to me as if you did everything in a single step, which is incorrect.  Let me give you a hint.  First one bromine adds, then the other bromine adds.  Why don't you post a drawing showing this?

Offline The apprentice

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Re: question about mechanism in chemistry
« Reply #6 on: December 16, 2021, 03:44:09 PM »
It sounds to me as if you did everything in a single step, which is incorrect.  Let me give you a hint.  First one bromine adds, then the other bromine adds.  Why don't you post a drawing showing this?



This was my first drawing, but I think it's wrong



Offline Babcock_Hall

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Re: question about mechanism in chemistry
« Reply #7 on: December 16, 2021, 04:27:25 PM »
A free carbocation is not formed in this reaction; instead, an intermediate with a formal positive charge on bromine in one resonance structure is formed.  Think about how many unshared pairs of electrons this particular bromine atom has.  When drawing this mechanism, it is also important to include correct curved arrows to and from this intermediate.

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