What is the point in washing the organic layer with NaOH?
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Washing an organic layer with a strong base separates a Brønsted acid into the aqueous layer. This is used for separating when there are multiple components.
For example, If I have a mixture of benzene and phenol (weakly acidic due to hydroxyl group) and added NaOH (strong base), the benzene would remain in the organic layer and the aqueous layer would now have the phenol salt, sodium phenolate.
What you would do next is up to the lab. You would probably pipet out the aqueous layer and add HCl, which would give you phenol again. Then you could pipet it out from under the aqueous layer, dry it, etc. So all that and you have the phenol separated from the benzene. Does that kind of make sense? Just acid and base reactions. Hope that helps!
For example, If I have a mixture of benzene and phenol (weakly acidic due to hydroxyl group) and added NaOH (strong base), the benzene would remain in the organic layer and the aqueous layer would now have the phenol salt, sodium phenolate.
What you would do next is up to the lab. You would probably pipet out the aqueous layer and add HCl, which would give you phenol again. Then you could pipet it out from under the aqueous layer, dry it, etc. So all that and you have the phenol separated from the benzene. Does that kind of make sense? Just acid and base reactions. Hope that helps!