The Effect of Sulfurhexafluoride on the Photochemistry of Aqueous Solutions

Rumfeldt, R. C.

doi:10.1139/v71-205

Cited by 6 publications

(3 citation statements)

References 7 publications

(9 reference statements)

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“…Note that spectrophotometry of SCN - solutions requires that the wavelengths of light used for the analysis be strictly controlled. SCN - undergoes photolysis below 230 nm, , and this photolysis is more efficient at lower pH values, such as those used in the current study . For this reason, a glass filter with a cutoff of 265 nm was used in the HP diode-array UV/vis instruments for wavelength control.…”

Section: Methodsmentioning

confidence: 99%

Acidic Aqueous Decomposition of Thiocyanogen

2004

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The aqueous reaction of acidic Cl2 with excess SCN- rapidly generates a UV-absorbing intermediate identified as an equilibrium mixture of thiocyanogen, (SCN)2, and trithiocyanate, (SCN)3(-). The decomposition of this mixture can be described as 3(SCN)2 + 4H2O --> 5HSCN + H2SO4 + HCN. Under our conditions the decomposition is sufficiently slow that its kinetics can be studied using standard stopped-flow methodology. Over the pH range 0-2 the decomposition rate law is -d[(SCN)2]/dt = (3/2)[k(disp)K(hyd)2[(SCN)2]2/([SCN-]2[H+]2 + K(SCN)3-[SCN-]3[H+]2 + K(hyd)[SCN-][H+])] with K(SCN)3(-) = 0.43 +/- 0.29 M(-1), K(hyd) = (5.66 +/- 0.77) x 10(-4) M2, and k(disp) = (6.86 +/- 0.95) x 10(4) M(-1) s(-1) at 25 degrees C and micro = 1 M. The K(SCN)3(-) and K(hyd) terms are significant enhancements relative to one of the rate laws conventionally cited. In the proposed mechanism, K(SCN)3(-) refers to the formation of (SCN)3(-) by association of SCN- with (SCN)2, K(hyd) refers to the hydrolysis of (SCN)2 to form HOSCN, and k(disp) is the rate constant for the bimolecular irreversible disproportionation of HOSCN, which leads ultimately to SO4(2-) and HCN. Ab initio calculations support the values of K(SCN)3(-) and K(hyd) reported herein. The high value for k(disp) indicates that HOSCN is a short-lived transient, while the magnitude of K(hyd) provides information on its thermodynamic stability. These results bear on the physiological role of enzymes that catalyze the oxidation of SCN- such as salivary peroxidase and myeloperoxidase.

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Section: Methodsmentioning

confidence: 99%

Acidic Aqueous Decomposition of Thiocyanogen

2004

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“…The apparatus and procedures are essentially the same as those described previously (2). In addition, an Oriel model C-13-62 low pressure Hg lamp operated with a stabilized power supply was used for most experiments.…”

Section: Methodsmentioning

confidence: 99%

“…It has recently been demonstrated (1,2) that the molecule SF, can be used quantitatively as a scavenger for solvated electrons generated either by the y-radiolysis or photolysis of a variety of anions in aqueous solution. Whereas with the radiation chemical systems the kinetic evidence has confirmed the specificity of SF, as a hydrated electron scavenger, no such evidence has been offered with the photochemical systems.…”

Section: Introductionmentioning

confidence: 99%

The Effect of SF₆ and N₂O on the 2537 Å Photolysis of Aqueous I⁻ and Fe(CN)₆⁴⁻

Crawford¹,

Rumfeldt²

1971

Can. J. Chem.

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The flash photolysis of di‐μ‐oxo‐bis(oxo‐molybdate(V)) acid aqueous solutions in the presence of excess thiocyanate

Martire

González

Feliz

et al. 1991

Int J of Chemical Kinetics

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The flash photolysis of the mono and di-thiocyanate complexes of @-ox0 bis(oxomolybdenum(V)) ( M O~O~( N C S ) , ( H~O )~_~~~~" where x = 1,2) has been studied in the system composed of perchloric acid solutions of M O~O~( H~O )~~~ in the presence of excess thiocyanate. Irradiation with light in the wavelength range 250-340 nm induced the formation of three reaction intermediates identified as p-0x0-bis (0x0-molybdenum(V)) species: Mo203( HZO): ' (A), Mo203(NCS) (H20):' ( B ) , and M O~O~( N C S )~( H~O )~~' (C).A rapid equilibria between the transient species is established before they decay following a first order kinetics. Intermediate A is the only species effective in promoting the observed decay leading to the end products Mo(V1) and Hz.The relative absorption spectrum of species A, B, and C are reported, as well as the measured stability constants for the formation of B and C in the temperature range 20-45°C. An overall mechanism is proposed.

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The Effect of Sulfurhexafluoride on the Photochemistry of Aqueous Solutions

Abstract: The effect of SF6 as a specific scavenger for en,-in the photolysis of aqueous solutions has been studied. The

Cited by 6 publications

References 7 publications

Acidic Aqueous Decomposition of Thiocyanogen

Acidic Aqueous Decomposition of Thiocyanogen

The Effect of SF₆ and N₂O on the 2537 Å Photolysis of Aqueous I⁻ and Fe(CN)₆⁴⁻

The flash photolysis of di‐μ‐oxo‐bis(oxo‐molybdate(V)) acid aqueous solutions in the presence of excess thiocyanate

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The Effect of Sulfurhexafluoride on the Photochemistry of Aqueous Solutions

Abstract: The effect of SF6 as a specific scavenger for en,-in the photolysis of aqueous solutions has been studied. The

Cited by 6 publications

References 7 publications

Acidic Aqueous Decomposition of Thiocyanogen

Acidic Aqueous Decomposition of Thiocyanogen

The Effect of SF6 and N2O on the 2537 Å Photolysis of Aqueous I− and Fe(CN)64−

The flash photolysis of di‐μ‐oxo‐bis(oxo‐molybdate(V)) acid aqueous solutions in the presence of excess thiocyanate

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The Effect of SF₆ and N₂O on the 2537 Å Photolysis of Aqueous I⁻ and Fe(CN)₆⁴⁻