The Influence of solvent and crown polyethers on the nucleophilic reactivity of potassium tert-Butylperoxide, potassium tert-Butoxide, and some other oxygen bases

✍ Scribed by Ruggero Curci; Fulvio di Furia

• Publisher: John Wiley and Sons
• Year: 1975
• Tongue: English
• Weight: 455 KB
• Volume: 7
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550070304

✦ Synopsis

The rates of reaction of t-BuOOK, t-BuOK, n-BuOOK, and p-MeCaY,OK with pnitrophenyl diphenylphosphinate 1 and with p-nitrophenyl benzoate 2 have been measured in toluene both in the absence and in the presence of crown polyether dicyclohexyl-18crown-6 3a. The rates of nucleophilic displacement on 1 by HOO-, t-BuOO-, and some "nonalpha" oxyanions in water have also been determined. Solvent transfer from water to toluene results in increasing the nucleophilic reactivity of the t-butyl hydroperoxide anion. Rate ratios Q. are given which allow one to estimate the enhanced reactivity of t-BuOO-(an a-nucleophile) compared to oxygen nucleophiles of comparable base strength toward 1 and 2. These are for substrate 1, Qa (water) 'v 6.5 and Q. (toluene) % 2.7; for substrate 2, Q. (water) % 5.5 and Q. (toluene) = 5. The hypothesis is advanced that solvation is not a major factor in determining the a-effect of the t-butyl hydroperoxide anion.