Phenanthroline iron

The iron phenanthroline derivative in Scheme 9 is a source of cyclobutadiene which can be trapped by maleanil. Both reactants bound to a polymer give, when oxidized, the polymeric adduct shown. By methaminolysis a derivative is formed, proving that cyclobutadiene is a free-existing intermediate in this reaction (74). 

Okada, T. et al., A comparative study of organic cobalt complex catalysts for oxygen reduction in polymer electrolyte fuel cells, J. Inorg. Organometal. Polym., 9,199,1999. Bron, M. et al., EXAFS, XPS and electrochemical studies on oxygen reduction catalysts obtained by heat treatment of iron phenanthroline complexes supported on high surface area carbon black, J. Electroanal. Chem., 535, 113, 2002. 

The apparent number of electrons transferred during ORR, , has been measured for several Fe-based catalysts obtained by the pyrolysis of various Fe precursors, including Fe-N4 chelates, iron phenanthroline or salts such as iron acetate. Values of n and the associated yields of hydrogen peroxide, %H202, are reported in Table 3.2 for Fe precursors and in Table 3.3 for Co precursors. %H202 is obtained from the following equation " %H202 = 100 (4 - n)tl. 

Bron, M., S. Fiechter, M. Hilgendorff, and P. Bogdanoff (2002). Catalysts for oxygen reduction from heat-treated carbon-supported iron phenanthroline complexes. J. Appl. Electrochem. 32, 211-216. 

Bron M, Fiechter S, Bogdanoff P, Tributsch H (2002) Thermogravimetry/spectrometry investigations on the formation of oxygen reduction catalysts for PEM fuel cells on the basis of heat-treated iron phenanthroline complexes. Fuel Cells 2 127-142... 

Figure 11.34 The effect of surfactants on the determination of iron. Phenanthroline method 20 //g Fe in 25 ml. Curve (1) cationic detergent (100 % active material) (2) anionic detergent (100% active material) (3) non-ionic detergent (100% active material) (4) industrial LAS-type detergent (74% LAS and 6% sodium tripolyphosphate) (5) formulated detergent (13% active material) (6) washing powder (15% LAS and 25% sodium tripolyphosphate) (7) mixed detergent (7 % LAS and 3 % non-ionic detergent) (8) sodium pyrophosphate (anhydrous) (9) sodium tripolyphosphate (10) soap. Broken line indicates turbidity. From Pakalns and Farrar [220].

In another version of this procedure the nonionic surfactant was first extracted batch-wise with sodium tetraphenylborate into 1,2-dichloroethane. The tetraphenylborate in the isolated organic phase was then titrated with a cationic surfactant, using Victoria Blue B as indicator (70). This titration can also be performed to an electrochemically detected end point. In this version, an excess of anionic surfactant is added to the cationic complex formed by the ethoxylated nonionic surfactant and potassium ion. The ion pair is extracted into dichloroethane, separated from the initial aqueous phase, then titrated with cationic surfactant in the presence of additional water. The ion pair of the anionic surfactant and Fe(II)(l,10-phenanthroline)3 is added as indicator. The end point of the titration is indicated when the last of the anionic surfactant is complexed by the cationic titrant, causing the iron-phenanthroline cation to migrate to the aqueous phase, where it is detected as a change in potential at a platinum electrode (71). 

---