Conklin, Martha Harriet (1987) Thermodynamics, kinetics and mechanisms of the reactions of S(IV) with Cu(II) and Fe(III). Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-03242008-134119
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Spectrosopic methods are used to determine the stability constant for the formation of [...], K = 1.8 [...] 0.6 x 10[...][...] for [...] = 0.4 M. Infrared and Raman measurements indicate that sulfite binds to the metal through both sulfur and oxygen. These results are compared to those of other first-row transition metal-sulfite complexes.
The reduction of Cu(II) is shown to proceed via (Cu(II))[...] and [...] intermediates. Copper(I), [...] and a mixed valence compound [...] are determined to be the principal products. The rate law is consistent with consecutive first-order reactions. Results are interpreted in terms of the initial formation of an inner-sphere complex which is followed by a rate-limiting electron transfer step. Previously accepted mechanisms for the trace metal catalysis of the autoxidation of [...] are discussed in light of these results.
A conditional stability constant for the formation of a Fe(III)-S(IV) complex at [...] = 0.4 M and pH 2.1 was determined spectroscopically. Raman measurements indicate that sulfite binds to the metal through oxygen. EPR experiments show that the reduction of Fe(III) to Fe(II) by S(IV) is a slow reaction at pH 2 ([...] 8 min). Various pathways for the formation of the Fe(III)-S(IV) species are examined to determine the most probable equilibrium species. Results are interpreted by comparing the stability and bonding of Fe(III)-S(IV) species with other Fe(III) complexes.
The rates of these internal redox reactions are too slow for this reaction to be important in the atmospheric autoxidation of S(IV), instead ternary metal-oxygen-sulfito complexes are proposed as the active catalytic species in aqueous atmospheric systems. Calculations based on the equilibrium constants obtained in this study indicate that metal-S(IV) complexes may be important equilibrium species in the absence of [...]-hydroxyalkylsulfonates. The catalytic autoxidation of [...] in aqueous systems appears to proceed via the formation of metal-sulfite complexes as a prelude to electron-transfer.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Engineering and Applied Science|
|Major Option:||Environmental Science and Engineering|
|Thesis Availability:||Restricted to Caltech community only|
|Defense Date:||2 June 1986|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||04 Apr 2008|
|Last Modified:||26 Dec 2012 02:35|
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