2,2-Diphenylpropanoic acid

Electrolysis of 3,3-diphenylpropanoic acid in acetic acid-acetate solution gives the products shown below. Propose mechanisms for the formation of each of the major products. 

Phenylpropanoic, 4-phenylbutanoic and 3,3-diphenylpropanoic acids were transformed with xenon difluoride to the corresponding fluorinated products without indication of free-radical rearrangement or cyclization, while phenylacetic acid in the presence of benzene produced diphenylmethane, indicating the involvement of a trivalent species (Scheme 44). Trifluoromethylbenzene was formed in 42% yield by reaction of trifluo-roacetic acid with benzene35-37. 

Heating 3,3-diphenylpropanoic acid with thionyl chloride is a reaction which does not produce the expected product this gives a nearly theoretical yield of a benzo[AJthiophene-2-carboxylic acid. When Vilsmeier reaction conditions are applied to the pyrimidylthioacetic acid (104.6), a fused thiophene ring is formed. 

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