Chemistry of iodine

Because of these rapid removal processes in the troposphere, the contribution of iodine to stratospheric photochemistry has not received much attention. However, Solomon et al. (1994) suggested that rapid transport from the lower troposphere into the upper troposphere and lower stratosphere via convective clouds could provide a mechanism for injecting such compounds into the stratosphere. While the relevant chemistry of iodine is not well known, it would be expected to interact with the CIO cycles in much the same way as BrO, e.g.,... 

Huie, R. E and B. Laszlo, The Atmospheric Chemistry of Iodine Compounds, in Halon Replacements—Technology and Science, ACS Symposium Series 611 (A. W. Miziolek and W. Tsang, Eds.), Chap. 4, Am. Chem. Soc., Washington, DC, 1995. 

Step 3. Read about the radiochemistry of iodine to improve your understanding of the radioanalytical chemistry of iodine. An old but helpful monograph is Radio chemistry of Iodine, NAS-NS-3062, by Milton Kahn and Jacob Kleinberg, Office of Scientific and Technical Information, US DOE, 103 pp (1977). A copy may be obtained from the instructor, the library, or internet search. Also read about ion-exchange theory and practice, and in particular, the relative affinity of anions for strong-base ion-exchange material. 

We shall set out here the structures of the compounds of Xe without enlarging on their stereochemistry. The close analogy with the structural chemistry of iodine will be evident, for the bond arrangements are for the most part consistent with the simple view of the stereochemistry of non-transition elements set out in Chapter 7. It will be equally evident that the difficulties encountered with certain valence groups in connection with the stereochemistries of Sb, Te, and I are also encountered here. 

This cycle is consistent with the known reaction chemistry of iodine, and he profiles of iodine species in the ocean and in sedimentary pore waters. The cycle allows for cycling of iodine in the marine environment through biological fixation. Thus, iodine appears to be an excellent carbon tracer in oceanic waters because of the difficulty in oxidizing I" to I03. This chemistry is in contrast to that of the sulfide system (25). 

Chemical reactivity decreases steadily from CI2 to I2, notably in reactions of the halogens with H2, P4, Sg and most metals. The values of E° in Table 16.1 indicate the decrease in oxidizing power along the series CI2 > Br2 >h, and this trend is the basis of the methods of extraction of Br2 and I2 described in Section 16.2. Notable features of the chemistry of iodine which single it out among the halogens are that it is more easily ... 

Radioiodine plays an important role in the diagnosis and treatment of various thyroid disorders. Production methods for various iodine isotopes, namely, and are briefly described in this paper. The chemistry of iodine and radiation effects in aqueous solutions and isotopic exchange reactions are also reviewed. An understanding of the chemistry of iodine is essential in isotope production, and for developing the procedure to prepare the radioactive iodine labeled pharmaceuticals. In radiochemical analysis of iodine, most environmental and biological samples can be accurately analyzed by neutron activation at trace levels. The use of potassium iodide (KI) has become an important remedy to prevent the harmful effects of radioiodine exposure under nuclear accident conditions. The inhibitory effect of KI administration on thyroid radioactive iodine uptake is discussed. 

Chemistry of Iodine Relevance to Radiochemical Studies and Nuciear Properties of Iodine Isotopes... 

The chemistry of iodine in aqueous solutions is very complex and extremely sensitive to oxidizing and reducing impurities and radiation effects, particularly at very low concentrations dealing with radioiodine. Iodide ions may be oxidized in acidic solutions by oxygen and/or hydrogen peroxide, as shown in the following reactions ... 

Radiation chemistry of iodine at very low concentrations in aqueous solutions was first investigated by Lin (1980b) and later by others (Ishigure et al., 1988). Iodide ions can easily be oxidized to Ij at higher concentrations in acidic... 

Iodine adsorbed onto the Pt surface is believed to be in the atomic state, and can be easily exchanged with non-radioactive iodine, I2 or I, in solution. This isotopic exchange procedure is very convenient for preparing labeled compounds, as discussed in Radiation chemistry of iodine in aqueous solutions . 

Practically, all radionucfides of iodine produced from target materials are purified and dissolved in dilute alkaline solution, or solution containing reducing agent to ensure that iodine stays in the reduced form of iodide (I ). However, in many cases where iodine activity occurs at very high concentrations in solution, a small fraction of iodate () is formed, most likely due to radiation-induced oxidation (discussed in Radiation chemistry of iodine in aqueous solutions ). This may cause some inconvenience when iodide is used. However, it is of interest to know that when iodine activity is administered for goiter prevention, radioiodine in the form of iodate is taken up by the thyroid rapidly as effectively as iodide (Cronquist etal.y 1971). 

Chemical analysis of trace iodine, in either biological or environmental samples, always encounters problems of interference from impurities and uncertainty in chemical yield of analysis. As discussed previously in Chemistry of Iodine Relevance to Radiochemical Studies and Nuclear Properties of Iodine Isotopes , the chemistry of iodine is very complex and isolation or purification of iodine from the sample is a major obstacle in a traditional chemical analysis. 

A. C. Chamberlain, et al.. Physical chemistry of iodine and removal of iodine from gas streams. J. Nucl. Energy, Paris A/B 17, 519-550 (1963). 

---