Photo-Fries Rearrangement & Barton Reaction Photo-Fries Rearrangement Photo-Fries Rearrangement Reaction Mechanism of Photo-Fries Rearrangement Reaction Example of Photo-Fries Rearrangement Reaction Barton Reaction Mechanism of Barton Reaction Examples of Barton Reaction

1. PRESENTED BY :
KESHAV KUMAR SINGH
Reg. No.:- Y19266023
Deptt. of Chemistry
DHSGU Sagar (M.P.)

2. Photo-Fries Rearrangement
Karl Theophil Fries was a German chemist. Fries is noted for the
discovery of the Fries rearrangement which is an important
reaction used in organic synthesis. The Fries rearrangement is a
rearrangement reaction of a phenolic ester to a hydroxyl aryl
ketone by catalysis of Lewis acids. It involves migration of acyl
group of phenol ester to the aryl ring. The reaction is ortho and
para selective and one of the two products can be favoured by
changing reaction conditions, such as temperature and solvent.

3.  Molecular rearrangement also can be promoted photochemically.
Phenolic esters rearrange on irradiation to give ortho and para acyl
phenols known as Photo-Fries rearrangement.
Photo-Fries Rearrangement Reaction

4. Mechanism of Photo-Fries Rearrangement
Reaction

6. Example of Photo-Fries Rearrangement
Reaction

7. Barton Reaction
The Barton reaction, also known as the Barton nitrite
ester reaction, is a photochemical reaction that involves
the photolysis of an alkyl nitrite to form a δ-
nitroso alcohol.

8.  The Barton reaction involves a homolytic RO–NO cleavage,
followed by δ-hydrogen abstraction, free radical recombination,
and tautomerization to form an oxime. Selectivity for the δ-
hydrogen is a result of the conformation of the 6-membered
radical intermediate. Often, the site of hydrogen atom
abstraction can be easily predicted. This allows the regio- and
stereo-selective introduction of functionality into complicated
molecules with high yield.

9. Mechanism of Barton Reaction

10. Examples of Barton Reaction