Iodine oxide, atmospheric

In the time scale covered by the calculation, the 137I in the particles results from in situ decay of 137Te. The low surface concentration is associated with the high volatility of iodine in an oxidizing atmosphere. In this same figure the 137Xe curves reflect their parent 137I curves to some extent. The surface concentration of this element probably does not represent a true vapor pressure equilibrium but just the thermody-... 

The few observations of nucleation in the free troposphere are consistent with binary sulfuric acid-water nucleation. In the boundary layer a third nucleating component or a totally different nucleation mechanism is clearly needed. Gaydos et al. (2005) showed that ternary sulfuric acid-ammonia-water nucleation can explain the new particle formation events in the northeastern United States through the year. These authors were able to reproduce the presence or lack of nucleation in practically all the days both during summer and winter that they examined (Figure 11.16). Ion-induced nucleation is expected to make a small contribution to the major nucleation events in the boundary layer because it is probably limited by the availability of ions (Laakso et al. 2002). Homogeneous nucleation of iodine oxide is the most likely explanation for the rapid formation of particles in coastal areas (Hoffmann et al. 2001). It appears that different nucleation processes are responsible for new particle formation in different parts of the atmosphere. Sulfuric acid is a major component of the nucleation growth process in most cases. 

Because of the presence of highly unsaturated fatty acids (as indicated by a high iodine value IV = 117) the rapeseed oil shows poor stability. It must be partially hydrogenated to increase this stability. The rapeseed oil conversion and the product distribution both depend on the Ni/Ce ratio of the mixed Ni-Ce-oxides and on the temperature. These catalwts appear more selective than Ni alone but lead to an important Z/E isomerization which gives rise to a drastic increase in the pourpoint value, llie use of a temaiy oxide (Ce-Ni-Al) allows a decrease in the extent of the Z/E isomerization. The results depend on the relative amount of each metal and the isomerization can be almost totally eliminated. Moreover, from some DSC experiments under an oxidative atmosphere, it appears that the resistance to oxidation can be improved, even at relatively high temperatures. 

Vikis and MacFarlane (1985) reported on reaction rates between I2 and O3 and the resultant formation of solid-phase iodine oxide aerosol. Coming from the opposite direction to the earlier work of Hamilton et al. (1963), this led the authors to suggest that the addition of O3 to nuclear reactor environments should be considered as a practical route for the removal of air-borne radioactive iodine species produced as fission by-products (see Radioactive Iodine Atmospheric Sources and Consequences ). 

Various oxygen-bonded iodine(V) derivatives are known [641-643]. Iodine pentoxide, I2O5, the most important and thermally stable iodine oxide, is prepared in the form of a hygroscopic, white solid by dehydration of iodic acid, HIO3, at 200 °C. It readily absorbs water from the atmosphere, giving the hydrate,... 

Alternative procedure. The following method utilises a trace of copper sulphate as a catalyst to increase the speed of the reaction in consequence, a weaker acid (acetic acid) may be employed and the extent of atmospheric oxidation of hydriodic acid reduced. Place 25.0 mL of 0.017M potassium dichromate in a 250 mL conical flask, add 5.0 mL of glacial acetic acid, 5 mL of 0.001M copper sulphate, and wash the sides of the flask with distilled water. Add 30 mL of 10 per cent potassium iodide solution, and titrate the iodine as liberated with the approximately 0.1M thiosulphate solution, introducing a little starch indicator towards the end. The titration may be completed in 3-4 minutes after the addition of the potassium iodide solution. Subtract 0.05 mL to allow for the iodine liberated by the copper sulphate catalyst. 

Substances that can oxidize to form a system of conjugated double bonds are frequently oxidized by atmospheric oxygen, iodine or iron(lll) salts. The products are chromo-phoric systems frequently containing ortho- or para-quinoid structure. 

Oxathiine derivatives lb 301,304 Oxathizine fungicides la 44 Oxazepam la 364 Oxazolidinthione derivatives lb 301 Oxeladine citrate lb 327 Oxidation, aluminium isopropoxide la 59 -, atmospheric oxygen la 60 -, chromic acid la 59, 60 -, hydrogen peroxide la 59 -, iodine la 60... 

The products of perfluorination are both white, very different from the original black hydrocarbon polymers. Both materials are moisture-sensitive powders and slowly degraded by atmospheric moisture, 6 more quickly than 5. The materials oxidize iodide ion to iodine owing to the presence of the N—F moiety. A series of iodometric titrations showed that 6 required twice the number of equivalents of titrant as did 5. This result supports the proposed structures 6 having twice as many N—F moieties as 5. 

Orozco-Cardenas ML, Narvaez-Vasquez J, Ryan CA (2001) Hydrogen peroxide acts as a second messenger for the induction of defense genes in tomato plants in response to wounding, systemin, and methyl jasmonate. Plant Cell 13 179-191 Palmer CJ, Anders TL, Carpenter LJ, Ktipper FC, McFiggans G (2005) Iodine and halocarbon response of Laminaria digitata to oxidative stress and links to atmospheric new particle production. Environ Chem 2 282-290... 

Consequently, the equivalent amount of iodine generated by the above reaction may be conveniently assayed by titration against a standard sodium thiosulphate solution. In this context a point of caution must be observed while KI is being oxidized under a strongly acidic medium so as to avoid simultaneous oxidation of the iodide by atmospheric oxygen that may result high erroneous titer values leading to false estimations. 

To prevent dimerization the concentration is kept low (10 3mol/l) but lower concentrations are allowed, when required by the bad solubility of the precursor. As an oxidizing agent 5.0 mol-% iodine in an atmosphere of air is frequently used. To prevent oxidation of the endproduct sometimes deaeration of the solvent and use of 100 mol- % iodine may be a better choice. Other useful agents are k-acceptors like tetracyanoethylene (TCNE) in dichloromethane as solvent. In most cases the helicenes are well separated from the irradiation mixture by evaporating the solvent and chromatography of the residue. In cases where the separation of the helicene and cis-olefin is difficult it is of advantage to irradiate until the olefin has completely reacted. 

We can, at this point, consider two well-known examples of dissociation of compounds At a pressure of one atmosphere, mercury forms an oxide below 300°C, but above this temperature the compound decomposes, while at lower oxygen pressures the decomposition temperature is lowered. Iodine atoms form iodine molecules at low temperatures, while at high temperatures the... 

The sulphites, both normal and acid, are easily oxidised, and in solution readily undergo atmospheric oxidation with the formation of sulphates. The oxidation proceeds more readily in neutral than in acid solution,2 and is accelerated by warming. The change in SOa-content of a solution of potassium metabisulphite (0-1 per cent.) kept in a stoppered bottle, observed by titration at intervals of aliquot portions with standard iodine solution, has been observed to be as follows 3... 

Instead of making a direct volumetric determination of the hydrosulphite it is possible to modify the process by estimating volumetrically the product of a primary reaction. For example the hydrosulphite solution may be submitted to atmospheric oxidation and the resulting acidity determined with standard alkali,2 or a mercuric salt may be reduced, the mercury produced being estimated subsequently by the addition of standard iodine solution and titration of the excess of iodine one molecule of hydrosulphite is equivalent to an atom of mercury and therefore to two atoms of iodine.4 Similarly, instead of the gravimetric estimation of silver as described above, the latter may be redissolved in nitric acid and determined volumetrically.5... 

The mechanism for the reaction is believed to be as shown in Eq. 15.170 (start with CH3OH, lower right, and end with CHjCOOH, lower left).180 The reaction can be initiated with any rhodium salt, e.g., RhCl3, and a source of iodine, the two combining with CO to produce the active catalyst, IRItfCO y. The methyl iodide arises from the reaction of methanol and hydrogen iodide. Note that the catalytic loop involves oxidative addition, insertion, and reductive elimination, with a net production of acetic acid from the insertion of carbon monoxide into methanol. The rhodium shuttles between the +1 and +3 oxidation states. The cataylst is so efficient that the reaction will proceed at atmospheric pressure, although in practice the system is... 

Chemical Properties.—When heated above 100° C. arsenic triiodide dissociates slowly into its elements above its melting point this decomposition becomes more rapid.11 In air, the products are arsenic, arsenious oxide and iodine, and the action proceeds slowly even below 100° C. and is rapid at 200° C. at higher temperatures the triiodide burns with a pale blue flame.12 Heated in an atmosphere of nitrogen in... 

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