Electron spin resonance and pulse radiolysis studies of some reactions of SO$sub 4$$.$$sup -$

Journal Article · Thu Nov 20 00:00:00 EST 1975 · J. Phys. Chem., v. 79, no. 24, pp. 2693-2700

OSTI ID:4126918

Chawla, O P; Fassenden, W

The in-situ photolysis of aqueous solutions of peroxydisulfate (S$sub 2$$O$$sub 8$$sup 2-$) was investigated as a source of radicals for ESR studies. This initiating system was found to be quite effective in that the SO$sub 4$$sup - $ so produced reacts readily with a variety of solutes; successful detection of a number of new radicals was possible. Attention was focused mainly on radicals resulting from reaction of SO$sub 4$$sup -$ with inorganic ions. Direct observations were made where possible, and spin trapping with CH$sub 2$ double bond NO$sub 2$$sup -$ or fumarate was used in other cases. Radicals directly observed include CO$sub 2$$sup -$ from formate, CO$sub 3$$sup -$ from bicarbonate, HO$sub 2$ from H$sub 2$$O$$sub 2$, and H$sub 2$NO from NH$sub 2$OH. The g factor of CO$sub 2$$sup -$ was found to be 2.00045 and the line width 2.3 G. No change in parameters was found over the pH range 0.8 to 4.6. The radical CO$sub 3$$sup -$ with g = 2.0113 and line width 4.4 G is reported for the first time in aqueous solution. No changes in the spectrum which might give evidence for the pK of this radical were found over the pH range 7.5 to 11.9. The pK for the dissociation PO$sub 3$$H$$sup -$ reversible H$sup +$ + PO$sub 3$$sup 2-$ was determined to be 5.9. Evidence for reaction of SO$sub 4$$sup -$ with NH$sub 3$, CN$sup -$, H$sub 2$PO$sub 4$$sup -$, and Cl$sup -$ was obtained by trapping the resultant radicals which are believed to be NH$sub 2$, CN, PO$sub 4$$sup 2-$, and Cl$sub 2$$sup -$, respectively. Pulse radiolysis studies confirm the formation of Cl$sub 2$$sup -$ from Cl$sup -$ (k/sub SO$sub 4$$sup -$+Cl$sup -$/ = 3.1 x 10$sup 8$ M$sup -1$ sec$sup -1$) by means of its absorption spectrum. Thus the reaction SO$sub 4$$sup -$ + Cl$sup -$ can be used to provide a source of Cl$sub 2$$sup -$ in neutral and basic solutions. Conductometric pulse radiolysis studies were carried out on several organic unsaturated compounds to clarify the nature of the SO$sub 4$$sup -$ reaction. It was concluded that SO$sub 4$$sup -$ adds to the simple olefins cyclohexene and allyl alcohol while a direct oxidation of benzene to hydroxycyclohexadienyl radical occurs in the time scale of less than 10 $mu$sec. (auth)

• Research Organization: Carnegie-Mellon Univ., Pittsburgh
• NSA Number: NSA-33-008923
• OSTI ID: 4126918
• Journal Information: J. Phys. Chem., v. 79, no. 24, pp. 2693-2700, Other Information: Orig. Receipt Date: 30-JUN-76
• Country of Publication: United States
• Language: English

Related Subjects

N40300* -Chemistry-Radiation Chemistry
400600* -Chemistry-Radiation Chemistry
*PEROXIDES- RADIOLYSIS
*SULFATES- RADIOLYSIS
ALCOHOLS
AMMONIA
AQUEOUS SOLUTIONS
CARBONATES
CARBOXYLIC ACID ESTERS
CHLORIDES
CYANIDES
CYCLOALKENES
ELECTRON SPIN RESONANCE
G VALUE
HYDROXYL RADICALS
ORGANIC NITROGEN COMPOUNDS
PH VALUE
PHOSPHATES
PYROPHOSPHATES
RADICALS
SPECTROSCOPY
TRAPPING