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Chemistry - Benzene

How do you speed up the halogenation of benzene (benzene + ICl) at room temperature? I need two points, could someone help me with this?

Thank you very much.
Original post by Shinjimonkey
How do you speed up the halogenation of benzene (benzene + ICl) at room temperature? I need two points, could someone help me with this?

Thank you very much.


@alow


Your time to shine?

I would have thought adding a catalyst would speed it up, same with increasing the volumes of the reagants or conversely increasing the pressure?
Reply 2
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alow
19
ICl is a solid or liquid near room temp, so increase the concentration of that if you're working in a solvent. Also you could use a Lewis acid catalyst, one that binds well with Cl, to speed up the iodination of benzene.
Original post by alow
ICl is a solid or liquid near room temp, so increase the concentration of that if you're working in a solvent. Also you could use a Lewis acid catalyst, one that binds well with Cl, to speed up the iodination of benzene.


Basically everything you say haha

OP, would you like to join the A-level chemistry whatsapp group we have?

@Shinjimonkey
Original post by alow
ICl is a solid or liquid near room temp, so increase the concentration of that if you're working in a solvent. Also you could use a Lewis acid catalyst, one that binds well with Cl, to speed up the iodination of benzene.


What kind of catalyst/acid can we use to speed the process? I know if you when you want to react benzene and Br2 you can use FeBr2 as a halogen-carrier catalyst, but what can mix when you are trying to do the halogenation of benzene with ICl?
Reply 5
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alow
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Original post by Shinjimonkey
What kind of catalyst/acid can we use to speed the process? I know if you when you want to react benzene and Br2 you can use FeBr2 as a halogen-carrier catalyst, but what can mix when you are trying to do the halogenation of benzene with ICl?


AlCl3 should work well.
Original post by alow
AlCl3 should work well.


If I was to use AlCl3, how would I get the electrophile? To get the electrophile I+ am I right in saying:
AlCl3 + ICl -> I+ + AlCL4-
Reply 7
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alow
19
Original post by Shinjimonkey
If I was to use AlCl3, how would I get the electrophile? To get the electrophile I+ am I right in saying:
AlCl3 + ICl -> I+ + AlCL4-


Yes that's right.
Original post by alow
Yes that's right.


Fantastic, thank you very much! If it is ok with you, I would like to ask another thing. I need to turn benzene into iodobenzene by adding I2. It is a similar process but how do you form a good I+ electrophile? is it:
I2 + HNO3 -> I+ + HNO3I-?
Reply 9
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alow
19
Original post by Shinjimonkey
Fantastic, thank you very much! If it is ok with you, I would like to ask another thing. I need to turn benzene into iodobenzene by adding I2. It is a similar process but how do you form a good I+ electrophile? is it:
I2 + HNO3 -> I+ + HNO3I-?


It's this:

2H+ + 2HNO3 + I2 ---> 2I+ + 2NO2 + 2H2O
Original post by alow
It's this:

2H+ + 2HNO3 + I2 ---> 2I+ + 2NO2 + 2H2O


Where do you get the H+ from?
Reply 11
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alow
19
Original post by Shinjimonkey
Where do you get the H+ from?


Some of the nitric acid molecules will be dissociated, some will not. It's effectively a proton from nitric acid.
Original post by alow
Some of the nitric acid molecules will be dissociated, some will not. It's effectively a proton from nitric acid.


I see. You are very helpful. Can I ask another question? Promise this will be last. How would you turn iodobenzene into iodo cyclohexane?
Reply 13
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alow
19
Original post by Shinjimonkey
I see. You are very helpful. Can I ask another question? Promise this will be last. How would you turn iodobenzene into iodo cyclohexane?


I would think you could just use really really high pressure and temperatures hydrogen and a Ni catalyst. I'm not massively sure about that though.
(edited 7 years ago)

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