Iodine/ions determination

D) 4 -[N-Ethyi-1 "-Methyl-2 -(4" -Methoxyphenyl)Ethylamino]Butyi-3,4-Dimethoxybenzoate Hydrochloride 10.3 g of 4 -iodobutyl-3,4-dimethoxybenzoate and 11.0 g of N-ethyl-p-methoxyphenylisopropylamine (obtained by catalytic reduction of an alcoholic solution of an excess quantity (60%) of p-methoxy-phenyl-acetone, to which was added a 33% (weight-for-weight) aqueous solution of ethylamine, with Pt as a catalyst), were boiled in 200 ml of methyl ethyl ketone for 20 hours, cooled and the iodine ion was determined the reaction was found to be complete. Then the methyl ethyl ketone was evaporated in vacuo and the residue was dissolved in 300 ml of water and 30 ml of ether the layers were separated and the water layer was extracted twice more with 20 ml portions of ether. 

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. 

VtntrAmt In a j litre bottle with a ground stopper, ion c.c. of distille.c w. t i. ev hypochlorite solution bring flen added and the bottle loser and shaken for a few moments, After addition of in t f. of the dilute siilpfmrie acid tlie excess of unabsorberl iodine is determined by titration with the thiosulphate solution,... 

A similar fitting procedure was also used in Ref. [61], but for determination of the contact radius from the purely diffusional quenching of IV-acetyltrypto-phanamide by iodine ions whose quenching efficiency was known to be 1 (kc = oo) [62]. These ions catalyze the intersystem crossing according to the general scheme (3.1), where Q is I-. Since electrostatic interaction are negligible in water (V = 0), the simplest Smoluchowski expression (3.23) was used in Eq. (3.4) to find the best fit ... 

In contrast with K collisions, Na produced almost no I ions, and for Li essentially no negative iodine ions were observed. Auerbach et al. explained this by noticing that the diabatic transition probability at the first crossing is practically zero due to the small crossing distance. The ionization probability is therefore determined by the second crossing which, as explained above,... 

Iodine is determined by igniting a sample in air with the full flame of a Bunsen burner and comparing the weight of the chromium(III) oxide produced with the initial weight of the sample. Chromium is determined in the usual manner by fusing the oxide with sodium peroxide and measuring the quantity of chromate ion produced. Anal. Calcd. for Crl3 Cr, 12.02 I, 87.98. Found Cr, 12.03, 11.73 I, 85.47, 87.65. 

Thereby we have determined the equilibrium concentrations of lead and iodine ions in a solution that is prepared by mixing solutions of sodium iodine and lead. 

Russel [142] developed a method based on the conversion of chlorine, bromine and iodine ions into the corresponding halogenated ethanols by reaction with ethylene oxide. Belcher et al. [143] offer a method for determining trace amounts of chloride ions, based on reaction with mercury phenylnitrate to give phenylmercury chloride, which is chromatographed with flame-ionization detection. 

Urine iodine was determined by Barker s modified alkaline incineration technique and catalytic reduction of ceric ion by arsenite salt. A random afternoon urine sample was collected and assayed. Urine iodine was expressed in pg/gm creatinine. 

Free bromine and iodine are determined by reduction with sodium thiosulfate. Both bromide and iodide ions are typically analyzed by precipitation or titration using silver nitrate or by titration with potassium dichromate (K2Cr207). 

Determine the charge of each ion. (a) oxygen ion with 10 electrons (b) aluminum ion with 10 electrons (c) titanium ion with 18 electrons (d) iodine ion with 54 electrons 74. Determine the charge of each ion. (a) tungsten ion with 68 electrons (b) tellurium ion with 54 electrons (c) nitrogen ion with 10 electrons (d) barium ion with 54 electrons... 

Column methods. Thyroxine can be isolated by ion-exchange column chromatography and its iodine content determined as described for PBI. 

In-depth analysis of implanted samples has been carried out by RBS (Rutherford backscattering) and SIMS (secondary ion mass spectroscopy). The RBS experiment on (CH) was used by Davenas et al. (54J for the determination of oxygen concentration. Samples implanted with iodine ions ( = lOOkeV.D = 5 x I0 ions/cm") would seem to be less sensitive to oxidation from the air than virgin samples. Two oxidation steps would arise the first step would concern the surface (during the first 4 h of exposure to the air), the other the volume (and would come from redistribution of oxygen atoms, which... 

In organic chemistry, you have met the idea that reactions occur in a number of steps. We call this the reaction mechanism. These steps do not take place at the same rate. The overall rate of reaction depends on the slowest step. We call this the rate-determining step. If the concentration of a reactant appears in the rate equation, then that reactant (or substances that react together to form it) appears in the rate-determining step. If a substance does not appear in the overall rate equation it does not take part in the rate-determining step. So, for the reaction between propanone and iodine, ions are involved in the rate-determining step but iodine is not. 

Iodine has many radioactive isotopes. Iodine-123 is a radioactive isotope used for obtaining images of the thyroid gland. Iodine-123 is administered to patients in the form of sodium iodide capsules that contain I ions. Determine the number of neutrons, protons, and electrons in a single 1 ion. 

The adherence of mercury to glass, i.e. tailing in presence of ozone, is probably due to the formation of an oxide. The oxidation of the iodide ion to iodine in solution is used to determine ozone quantitatively. 

Methods for iodine deterrnination in foods using colorimetry (95,96), ion-selective electrodes (94,97), micro acid digestion methods (98), and gas chromatography (99) suffer some limitations such as potential interferences, possibHity of contamination, and loss during analysis. More recendy neutron activation analysis, which is probably the most sensitive analytical technique for determining iodine, has also been used (100—102). 

The hberated iodine, as the complex triiodide ion, may be titrated with standard thiosulfate solution. A general iodometric assay method for organic peroxides has been pubUshed (253). Some peroxyesters may be determined by ferric ion-catalyzed iodometric analysis or by cupric ion catalysis. The latter has become an ASTM Standard procedure (254). Other reducing agents are ferrous, titanous, chromous, staimous, and arsenite ions triphenylphosphine diphenyl sulfide and triphenjiarsine (255,256). 

Bromide ndIodide. The spectrophotometric determination of trace bromide concentration is based on the bromide catalysis of iodine oxidation to iodate by permanganate in acidic solution. Iodide can also be measured spectrophotometricaHy by selective oxidation to iodine by potassium peroxymonosulfate (KHSO ). The iodine reacts with colorless leucocrystal violet to produce the highly colored leucocrystal violet dye. Greater than 200 mg/L of chloride interferes with the color development. Trace concentrations of iodide are determined by its abiUty to cataly2e ceric ion reduction by arsenous acid. The reduction reaction is stopped at a specific time by the addition of ferrous ammonium sulfate. The ferrous ion is oxidi2ed to ferric ion, which then reacts with thiocyanate to produce a deep red complex. 

One of the most required methods of determination of iodide-ions in praetiee of ehemieal analysis is photometrie determination of produets of iodination of organie eompounds. The oxidation of iodide to iodine ean be earned out suffieiently seleetively. But in ease of presenee of great abundanee of bromide-ions the seleetive oxidation of iodide-ions is problematie. The variants of determination of iodide-ions with different organie reagents are known, but the absenee of bromide-ions in a system is supposed in most of them. In natural objeets these halides are present simultaneously. 

To determine the ftq, value of Hg a solid sample is used, in which some of the iodine is present as radioactive 1-131. The count rate of the sample is 5.0 X 1011 counts per minute per mole of L An excess amount of Hg2I2(s) is placed in some water, and the solid is allowed to come to equilibrium with its respective ions. A 150.0-mL sample of the saturated solution is withdrawn and the radioactivity measured at 33 counts per minute. From this information, calculate the ft, value for Hg2l2. 

The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine CIO- is reduced to Cl-. The amount of iodine produced by the redox reaction is determined by titration with sodium thiosulfate, Na2S203 I2 is reduced to I-. The sodium thiosulfate is oxidized to sodium tetrathionate, Na2S406. In this analysis, potassium iodide was added in excess to 5.00 ml of bleach d = 1.00 g/cm3). If 25.00 mL of 0.0700 MNa2S203 was required to reduce all the iodine produced by the bleach back to iodide, what is the mass percent of NaCIO in the bleach ... 

Ion chromatography has been successfully applied to the quantitative analysis of ions in many diverse types of industrial and environmental samples. The technique has also been valuable for microelemental analysis, e.g. for the determination of sulphur, chlorine, bromine, phosphorus and iodine as heteroatoms in solid samples. Combustion in a Schoniger oxygen flask (Section 3.31 )is a widely used method of degrading such samples, the products of combustion being absorbed in solution as anionic or cationic forms, and the solution then directly injected into the ion chromatograph. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

The first step, as we have already seen (12-3), actually consists of two steps. The second step is very similar to the first step in electrophilic addition to double bonds (p. 970). There is a great deal of evidence for this mechanism (1) the rate is first order in substrate (2) bromine does not appear in the rate expression at all, ° a fact consistent with a rate-determining first step (3) the reaction rate is the same for bromination, chlorination, and iodination under the same conditions (4) the reaction shows an isotope effect and (5) the rate of the step 2-step 3 sequence has been independently measured (by starting with the enol) and found to be very fast. With basic catalysts the mechanism may be the same as that given above (since bases also catalyze formation of the enol), or the reaction may go directly through the enolate ion without formation of the enol ... 

Wang, C. Y., Bunday, S. D., and Tartar, J. G., Ion Chromatographic Determination of Fluorine, Chlorine, Bromine, and Iodine with Sequential Electrochemical and Conductometric Detection, Ana/. Chem. 55, 1983, 1617-1619. 

However, direct determination of both and k i by means of sampling followed by freezing to 77 °K and measurement of esr absorption intensities (for monomer) gave results inconsistent with step (106). Disproportionation of Mo(V)2 into Mo(rV) and Mo(VI) is also possible but no supporting evidence could be adduced. The titanous ion reduction of iodine displays the kinetics - ... 

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