a lvl chem qn
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ok this is the solution for a transformation qn.
can anyone explain the 2nd and 3rd step? i dont understand wats happening!
thx alot
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1st step: halogenation without a lewis acid catalyst is possible due to the electron donating groups (methy and hydroxyl)
2nd step: phenol is acidic enought to react with NaOH to form phenoxide ion
3rd step: pheonoxide ion acts as a nucleophile to attack the alky halide (nucleophilic substitution)
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quailmaster has pretty much covered it. Any further questions?
Note that CCl4 solvent is used (in the 1st step) if electrophilic aromatic substitution of only one Cl to the para position is desired. If aqueous solvent is used, disubstitution / dichlorination of Cl to both the para and the available ortho position will be achieved, due to the strongly polar water molecule inducing a stronger temporary dipole in the non-polar halogen molecule.
And in case you're wondering why (in step 2) you need to deprotonate the phenolic group, it is to generate a sufficiently strong nucleophile. (If not for the negative formal charge on the O atom of the phenoxide ion, the O atom of phenol actually has a partial positive charge on its resonance hybrid, due to delocalization of the O atom's lone pair into the benzene ring, which makes it an unfeasibly weak nucleophile. Hence, deprotonation by NaOH is necessary.)
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ty