Iodine Complexation

A poly( -vinyl-2-pyrroHdinone)-iodine complex [25655-41-8] (PVP-iodine), has been used extensively in hospitals and elsewhere because of its germicidal, bactericidal, fungicidal, and generally disinfecting properties (150). It is sold as a solution that contains about 10% available, or active, iodine and about 5% inactive iodine, in the form of iodide ion (see Disinfectants and antiseptics Industrial antimicrobial agents). 

Iodine Complexes. The small molecule/PVP complex between iodine and PVP is probably the best-known example (95) and can be represented as follows ... 

Amylose [9005-82-7] (C Hio05) (/br use in iodine complex formation). Amylopectin was removed from impure amylose by dispersing in aqueous 15% pyridine at 80-90 (concn 0.6-0.7%) and leaving the soln stand at 44-45° for 7 days. The ppte was re-dispersed and recrystd during 5 days. After a further dispersion in 15% pyridine, it was cooled to 45°, allowed to stand at this temperature for 12hours, then eooled... 

Preswelled Sephacryl S-1000 was prepared in a K26/100 column (88 X 2.6 cm). Equilibration with 0.005 M NaOH containing 0.002% NaN3 at a flow rate of 0.67 ml/min was achieved after 20 hr. Sample solutions were applied with a 5-ml injection loop. The mass and iodine-complexing potential of separated glucan components was determined off-line for each of the subsequently eluted 5-ml fractions. Based on the determined mass of carbohydrate for each of the fractions, elution profiles such as Fig. 16.1 were constructed. 

The molecular uniformity of constituting components of a nb/lcb glucan fraction of potato starch was investigated with Sepharose CL 2B (Fig. 16.16) as well as with Sephacryl S-1000 (Fig. 16.17). Therefore, each of the subsequently eluted 3-ml fractions was analyzed on their potential to form inclusion complexes with iodine, a sensitive test for the presence of nb/lcb glucans. Results are shown in Fig. 16.17 in terms of branching index, the ratio of extinction of pure iodine solution and of nb/lcb glucan/iodine complex the higher the index, the more pronounced the nb/lcb characteristics. 

FIGURE 16.17 Nonbranched/long chain branched glucans of potato starch dissolved in hot water-steam and 0.1 M NaOH 1.2 ml of the 18-mg/ml solution was separated on Sephacryl S-1000 (95 X 1.6 cm) 3-ml fractions were collected for further analysis normalized (area = 1.0) eluogram profiles (ev) constructed from an off-line determined mass of carbohydrates for each of the fractions branching index ( ) determined from iodine-complexing potential of individual 3-ml fractions flow rate 0.40 ml/ min V ,i = 75 ml, Vtot = 162 ml eluent 0.005 tA NaOH. 

Suppose 25.00 mL of an aqueous solution of iodine was titrated with 0.0250 M Na2S20,(aq), with starch as the indicator. The blue color of the starch-iodine complex disappeared when 27.65 mL of the thiosulfate solution had... 

Polycyclic aromatic hydrocarbons, indole and quinoline derivatives, naphthylamines, azulenes Silica gel G Formation of oxidation products via the initially formed iodine complexes [15]... 

Polycyclic aromatic hydrocarbons Silica gel G Monovalent oxidation of the iodine complexes via radical cations yields dimeric or tetrameric aromatics [16]... 

Rendleman, J. A. (2003). The reaction of starch with iodine vapor. Determination of iodide-ion content of starch-iodine complexes. Carbohydr. Polym. 51,191-202. 

The Mulliken theory of overlap and orientation principle (cf. Chap. 2) predicts that stabilization in the molecular complex formation should essentially be determined by the overlap of the donor HO and the acceptor LU. The iodine complex of trimethylamine will take the form... 

The hexamine-iodine complex deflagrates at 138°C. See other IODINE compounds... 

Miyasaka, K. PVA-Iodine Complexes Formation, Structure and Properties. Vol. 108, pp. 91-130. 

Tapioca and maize amylopectins have been sub-fractionated by fractional precipitation from aqueous solution with increasing amounts of methanol,64 71 and potato amylopectin by preferential precipitation on electrodialysis of the iodine complex.72 When these three amylopectins were subjected to chromatography, and eluted with a neutral buffer, all were found to consist of several sub-fractions.70... 

Rundle and coworkers166 found that the wave length of maximum absorption (Amflx) of the amylose-iodine complex is related to the chain length... 

Observed Relationship Between Xmax and D. P. for Amylose-Iodine Complexes... 

Interestingly, there is a tendency to obtain only certain stoichiometries of crownether iodine complexes in the solid state, i.e. product formation is governed by packing behaviour and solubility of the particular complexes. In solution, 1 1 adducts are often the predominant species.24,31 34... 

Schnepfe [83] has described yet another procedure for the determination of iodate and total iodine in seawater. To determine total iodine 1 ml of 1% aqueous sulfamic acid is added to 10 ml seawater which, if necessary, is filtered and then adjusted to a pH of less than 2.0. After 15 min, 1 ml sodium hydroxide (0.1 M) and 0.5 ml potassium permanganate (0.1M) are added and the mixture heated on a steam bath for one hour. The cooled solution is filtered and the residue washed. The filtrate and washings are diluted to 16 ml and 1ml of a phosphate solution (0.25 M) added (containing 0.3 xg iodine as iodate per ml) at 0 °C. Then 0.7 ml ferrous chloride (0.1 M) in 0.2% v/v sulfuric acid, 5 ml aqueous sulfuric acid (10%) - phosphoric acid (1 1) are added at 0 °C followed by 2 ml starch-cadmium iodide reagent. The solution is diluted to 25 ml and after 10-15 min the extinction of the starch-iodine complex is measured in a -5 cm cell. To determine iodate the same procedure is followed as is described previously except that the oxidation stage with sodium hydroxide - potassium permanganate is omitted and only 0.2 ml ferrous chloride solution is added. A potassium iodate standard was used in both methods. 

The potential colorimetric use of the iodine complexes of methimazole in CHCl and CCI4 is studied. The absorption maximum of methima-zole-iodine complex at 269 nm could be used analytically. 

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