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Why is HCl used in the washing step in friedel-crafts reaction?

David Lovering  Follow
Right, My mistake :-)

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All About Business  Follow
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Okay so the difference between the product and excess t-butyl chloride is that they contain different halides and the product contains two aromatic ring structure. (Not too sure where this is going xD)

Yes, and the biphenyl product is much larger than the t-butyl chloride, and what do you know about boiling points of molecules?

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Carolyn Barnett  Follow
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Personally, when doing an extraction I like to analyze where all the reactants/product like to be, in de organic layer or in the (acidic) water layer. HCl doesnt just magically destroy or remove an impurity.

So in your reaction mixture you have: your biphenyl product, excess t-butylchloride, formed HCl from the reaction, and FeCl2 (are you sure you didn't use FeCl3?).
Definately, the product and the excess tbutylchloride stay in the organic layer. HCl and the Iron salt will go to the water layer. (Anorganic salt generally go to the water layer.

So you are left with your product and excess tbutylchloride in the dichloromethane layer after washing. How do you seperate these 2 from eachother? What physical property do they really differ in when you look at them?

Thank you so much for your response critzz!!! I really need to understand how workups work before my lab exam next week and unfortunately, my lab coordinator is leaving me in the dust.

Yes, I meant to say FeCl3.
Okay so the difference between the product and excess t-butyl chloride is that they contain different halides and the product contains two aromatic ring structure. (Not too sure where this is going xD)

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Chuck Britton  Follow
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YOu neeed acid/water to decompose the intermediate that leads to form the ketone
http://www.organic-chemistry.org/namedreactions/friedel-crafts-acylation.shtm

He did a friedelcrafts alkylation though. But I guess you use HCl to quench the reaction and keep all salts desolved? If you'd use NaOH solution for example you would get nasty insoluble Fe(OH)3 salts. I'm not sure though in this case.

The dark (brown?) colour probably comes from the hydrolized FeCl3 salts (Fe(H2O)6).

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Cramer Beasly  Follow
OH YEAH!!!! Tertbutyl chloride has a low bp (around 50°C)!!! We did a simple distillation but I thought it was to remove DCM only. Thank you that makes so much sense!

But what was the point of washing with HCl? There was a dark colour change when HCl was added.

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Dare Robertson  Follow
YOu neeed acid/water to decompose the intermediate that leads to form the ketone
http://www.organic-chemistry.org/namedreactions/friedel-crafts-acylation.shtm

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Daniel TerBush  Follow
Personally, when doing an extraction I like to analyze where all the reactants/product like to be, in de organic layer or in the (acidic) water layer. HCl doesnt just magically destroy or remove an impurity.

So in your reaction mixture you have: your biphenyl product, excess t-butylchloride, formed HCl from the reaction, and FeCl2 (are you sure you didn't use FeCl3?).
Definately, the product and the excess tbutylchloride stay in the organic layer. HCl and the Iron salt will go to the water layer. (Anorganic salt generally go to the water layer.

So you are left with your product and excess tbutylchloride in the dichloromethane layer after washing. How do you seperate these 2 from eachother? What physical property do they really differ in when you look at them?

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