Wijs solution

Commercially available Wij s solution, which gives satisfactory results, may be used. 

Dissolve 16gof commercially availableiodinemonochloride(ICI)in 1 litre of A.R. glacial acetic acid. Filter rapidly through a filter paper and store in amber-coloured glass-stoppered bottle in a dark place at a temperature below 30°C. 

Dissolve 8 g of pure ICI3 (iodine trichloride) and 9 g of resublimed iodine separately in500 ml of A.R. glacial acetic acid each. Wann on a water bath, if dissolution is not complete at room temperature. Add iodine solution gradually to ICI3 solution with constant shaking until a red-brown colour appears. Add 20-30 ml more. Heat on a water bath for about 15 minutes, cool and store. 

What is a primary standard Give some examples. 

What is the general procedure for preparing a solution of detinite normality (say N/10) of a substance which is not a primary standard  

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Wijs solution (for iodine number) dissolve 13 g resublimed iodine in 1 liter of glacial acetic acid (99.5%), and pass in washed and dried (over or through H2SO4) chlorine gas until the original thio titration of the solution is not quite doubled. There should be only a slight excess of iodine and no excess of chlorine. Preserve the solution in amber colored bottles sealed with paraffin. Do not use the solution after it has been prepared for more than 30 days. 

Iodine monochloride is used as an analytical reagent to determine iodine values of ods and fats. It is dissolved in glacial acetic acid (Wijs solution) for the analysis. ICl is used in organic synthesis. It also is used as a topical antiseptic. 

CAUTION Wijs solution is hazardous and should be handled with gloves in a fume hood. Materials... 

Wijs solution, in glacial acetic acid (Fisher Scientific store in the dark at 25° to 30°C and keep tightly sealed)... 

Add 20 ml cyclohexane and swirl to dissolve the sample. Add 25 ml of Wijs solution using a pipet (not a graduated cylinder) for best control of data. Seal the flask with a glass stopper and place in a cool (25° to 30°C), dark place for 1 or 2 hr depending on expected IV (time must be consistent across samples). Also prepare a blank using all ingredients except the lipid sample. 

Cyclohexane serves to solubilize the fat. It should be purchased new and dated if the data become erratic and no other source can be found for the problem, new cyclohexane should be obtained. Wijs solution is an iodine/chlorine solution in acetic acid. It acts to provide iodine monochloride (in excess) which reacts with the double bond. Wijs solution is sensitive to temperature, moisture, and light, and must be stored as recommended above. 

This analysis measures the unsaturation in a lipid system. It is based on the fact that halogens will react with aliphatic double bonds in a measurable way. Initially the sample is mixed with the Wijs solution, which contains excess iodine monochloride (IC1). The IC1 binds to the double bond(s) as follows ... 

Wijs Solution Dissolve 13 g of resublimed iodine in 1000 mL of glacial acetic acid. Pipet 10.0 mL of this solution into a 250-mL flask, add 20 mL of potassium iodide TS and 100 mL of water, and titrate with 0.1 N sodium thiosulfate, adding starch TS near the endpoint. Record the volume required as A. Set aside about 100 mL of the iodine-acetic acid solution for future use. Pass chlorine gas, washed and dried with sulfuric acid, through the remainder of the solution until a 10.0-mL portion requires not quite twice the volume of 0.1 N sodium thiosulfate consumed in the titration of the original iodine solution. A characteristic color change occurs when the desired amount of chlorine has been added. Alternatively, Wijs Solution may be prepared by dissolving 16.5 g of iodine monochloride, IC1, in 1000 mL of glacial acetic acid. Store the solution in amber bottles sealed with paraffin until ready for use, and use within 30 days. 

Total Halogen Content Pipet 10.0 mL of Wijs Solution into a 500-mL Erlenmeyer flask containing 150 mL of recently boiled and cooled water and 15 mL of potassium iodide TS. Titrate immediately with 0.1 N sodium thiosulfate, recording the volume required as B. 

The iodine mono-chloride solution is the Hiibl solution, the iodine trichloride solution, is the Wijs solution. In either case, the exact... 

Iodine monochloride. Mol. wt. 162.38, m.p. 14°, 27° b.p. 97°. Suppliers Alfa, E, F, KK, MCB. A solution of iodine monochloride in acetic acid (Wijs solution) is used to determine iodine values of fats and oils. 

The ASTM standard does not give restriction to the iodine value of methyl esters but the European biodiesel standard (EN 14214) states that the iodine value should be no more than 120. JCME is within the requirements of EN 14214. The iodine number of conventional (automotive) diesel fuel is reported to be 10. Based on the results shown in Table 2, the iodine value of the methyl esters differs only slightly from that of their parent oil. The iodine value derived from the GC-MS chromatograms are higher than those derived from the Wijs solution method, mainly because Equation 1 assumes full iodonization and treats all the double bonds as being equally reactive to oxidation. ... 

In the test method (ASTM D-2078), a sample is dissolved in chloroform and reacted with Wijs solution for 30 min in the dark at 25°C. At the end of the reaction, the solution is mixed with potassium iodide (KI) and titrated with sodium thiosulfate and starch indicator and compared to a blank determination. 

The amount of sample weighed is dissolved in 15 ml tetrachloromethane in a conical flask. From a burette, 25.00ml of Wijs solution (see Note) is added. The flask is closed, the contents are mixed and allowed to stand in the dark at about 20 for (i) 1 h, if it is certain that no polymerized or oxidized material is present (ii) 2 h, if polymerized or oxidized materials may be present. 

Note. Wijs solution (ICl solution 0.2mol/l) is commercially available. 

That the figure for the iodine value depends on the method of determination employed, and that exact conditions of experiment are necessary in the case of this material, has been conclusively proved. Abraham and Cockton showed the necessity for specifying the exact quantity to be taken in the official iodine monochloride method using 1 0 g and 25 ml of approximately 0-2N Wijs solution, the iodine value increased from 27-3 in one hour to 29 9 in five hours, whereas using 0 2 g and the same quantity of iodine solution the results were of the order of 49. The jB.P. method uses 1 g with an iodine value range of 18 to 32, whilst the f/.5.F. limits are 18 to 36 with 0-78 to 0-82 g of wool fat. The length of time of exposure to the iodine does not appear to affect the result appreciably. 

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