Periodic acid reagent

The periodic acid reagent is prepared by dissolving 1 - 0 g. of paraperiodic acid HglOg in 200 ml. of distilled water. 

Place 2 ml. of the periodic acid reagent in a small test tube, add one drop (no more—otherwise the silver iodate, if formed, will fail to precipitate) of concentrated nitric acid, and shake well. Add one drop or a small crystal of the compound to be tested, shake the mixture for 15-20 seconds, and then add 1-2 drops of 3 per cent, silver nitrate solution. The instantaneous formation of a white precipitate of silver iodate is a positive test. Failure to form a precipitate, or the appearance of a brown precipitate which redissolves on shaking, constitutes a negative test. 

Other reagents are relatively specific for only one or several amino acids. These include the ninhydrin-bicarbonate reagent (P3) for phenylalanine and aspartic acid Ehrlich s reagent (S33) for tryptophan the nitrosonaphthol reagent (Al) for tyrosine the periodic acid reagent (S37) for serine, hydroxylysine, and ethanolamine the nitro-... 

The ninhydrin reagent (No. 178) is the most sensitive for detection of the free amino sugars (lower limit of detection, 0.5 (xg), whereas a periodic acid reagent, followed by thiobarbituric acid, although less sensitive (3 to 5 (Xg), gives characteristic colors (red for the N-acetyl compounds). The Elson-Morgan test can be used on cellulose MN 300 A but the characteristic color formation is hindered on cellulose MN 300 [39]. 

An alternative procedure for the above test is as follows. Mix 2-3 ml. of 2 per cent, aqueous paraperiodic acid solution with 1 drop of dilute sulphuric acid (ca. 2 5N) and add 20-30 mg. of the compound. Shake the mixture for 5 minutes, and then pass sulphur dioxide through the solution until it acquires a pale yellow colour (to remove the excess of periodic acid and also iodic acid formed in the reaction). Add 1-2 ml. of Schiff s reagent (Section 111,70) the production of a violet colour constitutes a positive test. 

CEBSSS Give the products of periodic acid oxidation of each of the fol lowing How many moles of reagent will be consumed per mole of substrate in... 

The oxidation of 4-bromophenols to quinones can also be accompHshed using periodic acid (113). A detailed study of this reagent with stericaHy hindered phenols provided insight about the quinonoid product (114). The highest yield of 2,6-di-/-butyl-l,4-ben2oquinone [719-22-2] is for the case of R = OCH. The stilbene stmcture [2411-18-9] is obtained in highest yield for R = H. 

A variety of oxidative reagents can be used to convert 17-hydroxypregnanes containing an additional oxygen function at C-20 into 17-ketoandrostanes. Among the most widely used have been chromium trioxide, lead tetraacetate, periodic acid and sodium bismuthate. 

Lead tetraacetate and periodic acid complement one another in their applicability as reagents for glycol cleavage. The water sensitive lead tetraacetate is used in organic solvents, while periodic acid can be used for cleavage of water-soluble diols in aqueous medium. 

Unique methods based on new principles have been developed within the past 10 years. Threonine (27,28,249) is oxidized by lead tetraacetate or periodic acid to acetaldehyde, which is determined by photometric analysis of its p-hydroxydiphenyl complex or iodometric titration of its combined bisulfite. Serine is oxidized similarly to formaldehyde, which is determined gravimetrically (207) as its dimedon (5,5-dimethyldihydro-resorcinol) derivative or photometric analysis (31) of the complex formed with Eegriwe s reagent (l,8-dihydroxynaphthalene-3,5-disulfonic acid). It appears that the data obtained for threonine and serine in various proteins by these oxidation procedures are reasonably accurate. [Block and Bolling (26) have given data on the threonine and serine content of various proteins. ]... 

The two reagents (periodic acid and lead tetraacetate) are complementary, since periodic acid is best used in water and lead tetraacetate in organic solvents. When three or more OH groups are located on adjacent carbons, the middle one (or ones) is converted to formic acid. 

Periodic acid-Schiff reagent Detects glycoproteins as pink bands after electrophoretic separation. 

Figure 52-3. Diagrammatic representation of the major proteins of the membrane of the human red blood cell separated by SDS-PAGE. The bands detected by staining with Coomassie blue are shown in the two left-hand channels, and the glycoproteins detected by staining with periodic acid-Schiff (PAS) reagent are shown in the right-hand channel. (Reproduced, with permission, from Beck WS, Tepper Ri Hemolytic anemias iii membrane disorders, in Hematology, 5th ed. Beck WS [editor]. The MiT Press, 1991.)...

The band number refers to the position of migration on SDS-PAGE (see Figure 52-3). The glycophorins are detected by staining with the periodic acid-Schiff reagent. A number of other components (eg, 42 and 4.9) are not listed. Native spectrin is... 

PAS Periodic acid-SchiflF reagent PBA Polyclonal B cell activators PBC Primary biliary cirrhosis PBL Peripheral blood lymphocytes PBMC Peripheral blood mononuclear cells PBN N- e f-butyl-a-phenylnitrone PBS Phosphate-buffered saline PC Phosphatidylcholine... 

During the preparation of the quaternary oxidant tetraethylammonium iodate from the aqueous reagents, the residue after vacuum evaporation of most of the water exploded, breaking the flask. This was attributed to possible presence of excess periodic acid in the reaction mixture [1]. Further details and precautions to avoid heating the salt, normally stable in storage, are given [2],... 

Glycerol can be oxidized to formaldehyde by periodic acid and the formaldehyde measured spectrophotometrically at 570 nm after reaction with chromotropic acid, or fluorimetrically after the addition of diacetylacetone and ammonia. The chromotropic acid reagent consists of 8-dihydroxynaphthalene-3,6-disulphonic acid dissolved in 50% sulphuric acid. 

Periodic acid reacts well in aqueous solution. Usually, if the reactant has to be run in organic solvents, lead tetraacetate is used as the reagent. Interestingly, periodic acid will not act on a-keto acids or a-hydroxy acids whereas lead tetraacetate wiU. The corresponding reactions are actually oxidative decarboxylations. 

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