Oxidation of fluorenes by ammonium meta vanadate—a kinetic study

✍ Scribed by S. Narasimhan; N. Venkatasubramanian

• Publisher: John Wiley and Sons
• Year: 1979
• Tongue: English
• Weight: 589 KB
• Volume: 11
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550110807

✦ Synopsis

Abstract

The oxidation of fluorene by vanadium(V) in aqueous acetic acid containing sulfuric acid (1.0__M__) at 50°C produces fluorenone and 2‐hydroxy diphenyl 2′‐carboxaldehyde. The order with respect to each reactant is found to be 1. The order dependence on sulfuric acid concentration is 4, indicating that V(OH)~2~^3+^ could be the active species. An increase in the acetic acid percentage in the solvent medium increases the rate of the reaction. The effect of solvent variation has been discussed in the light of the acidity function and the polarity of the medium. The effect of substituents on the rate has been studied for seven substituted fluorenes, and a linear relationship exists between log k versus σ values with the slope ρ = ‐3.2. A small isotope effect is observed for the oxidation of the parent compound (k~H~/k~D~ = 1.2). The effect of temperature on the rate of the reaction has been studied, and the activation parameters are discussed. A mechanism involving the rate‐limiting formation of a cation‐radical intermediate is proposed.