Chemistry, asked by uttamraj6535, 1 month ago

d) Explain why a small amount of phenol is obtained as a side product in photo-Fries rearrangement reaction?​

Answers

Answered by RohitVaishnavv
0

Answer:

Fries rearrangement is an organic rearrangement reaction

Explanation:

The Fries Rearrangement is an organic rearrangement reaction that involves the transformation of an aryl ester into a hydroxy aryl ketone using a Lewis acid catalyst and an aqueous solution. An acyl group from the phenolic ester migrates to the aryl ring in this reaction. It's vital to note that Fries rearrangement is ortho and para selective, meaning that the acyl group binds to the aryl ring in either the ortho or para orientations. Modifying the reaction conditions can affect the reaction's selectivity (such as the temperature under which the reaction is conducted, or the solvent used in the reaction).

Initially, the acyl group's carbonyl oxygen forms a compound with the Lewis acid catalyst (usually AlCl3). Because the carbonyl oxygen is richer in electrons and hence a stronger Lewis base, the complexation of the carbonyl oxygen is preferred over the complexation of the phenolic oxygen.

The link between the phenolic oxygen and the acyl complex is now polarised, causing the AlCl3 bond to the phenolic oxygen to rearrange. An acylium carbocation is formed as a result of this process.

An electrophilic aromatic substitution process is used by the acylium carbocation to attack the aromatic ring.

It is important to note that the orientation of this electrophilic aromatic substitution is temperature-dependent. Low reaction temperatures favour substitutions at the para position and relatively high temperatures favour ortho substitution.

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