Cation, solvent, and substituent effects on the decay kinetics of alkali metal salts of diaryl disulfide radical anions in nonaqueous solutions
✍ Scribed by Tokuji Miyashita; Minoru Matsuda
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 406 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
The transient diary1 disulfide radical anions (RSSR-) were produced in nonaqueous solutions at room temperature by the flash photolysis of a solution of arylthiolate ion pair in the presence of the excess corresponding disulfide. The transient spectra were almost identical with those obtained from y-radiolysis of the disulfides in 77 K 2methyl-tetrahydrofuran (MTHF) glassy matrix. The spectra of disulfide radical anions in nonaqueous solutions were changed by cations, solvents, and para-substituents depending on the ion pair properties. The tighter ion pairs showed a shift of absorption band to the shorter wavelength. The disulfide radical anions decay by a unimolecular dissociation reaction to yield thiolate anion and thiyl radical. The decay kinetics were first-order in the initial time region. The rate constants obtained were changed by the counter cations in the order Na' > K' > Cs' > Li', and by solvents. The tighter ion pairs of the disulfide radical anions showed faster dissociation reaction. This is due to stabilization of a transition state with the counter cation.