Abstract
This paper reviews the recent literature on the title reactions and updates a 1988 review.
Highlights
Both of these reactions, last reviewed in 1988 [1], are nucleophilic displacements on a peroxide oxygen of the peroxydisulfate ion
The products are aromatic sulfates whose orientation relative to the phenolic group is preferentially para in the Elbs oxidation and ortho in the Boyland-Sims case
These sulfates are useful in synthesis themselves or may be hydrolyzed in acid to the dihydric phenols
Summary
Low yields and recovery of starting material A significant disadvantage to the Elbs Oxidation is the low yield; yields are seldom above 50% But it is characteristic that large quantities of starting material can be recovered This is true even with a ratio of peroxydisulfate to phenol greater than one. There is some literature to suggest that substitution ortho or meta to the phenolic oxygen yields a more stable (less reactive) radical than the para-substituted case; Wright et al have calculated bond dissociation energies for the formation of phenoxyl radicals from 36 o-,m-, and p-substituted phenols. [30,31] An important developing area is the use of salts of peroxydisulfate which are soluble in organic solvents by virtue of large organic cations in place of the commercially available ammonium, sodium, or potassium salts This approach has not yet been reported for the Elbs or Boyland-Sims oxidations. Isolated yields are given in percent; if no yield was reported, that is indicated by a dash
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