Identification Tests Bromide

Borneol, (S3)66, 96 Bornyl Acetate, 460, 648 Z-Bornyl Acetate, 460 Bound Styrene, 782 Bovine Rennet, 133, (S3) 18 Brewer s Yeast, 440 Brilliant Blue FCF, 139, (S3)24 Bromelain, 132, 786, (S3)18 Bromide Identification Test, 753 Brominated Vegetable Oil, 48 Bromine, 0.1 N, 856 Bromine TS, 850 Bromine Water, 850 Bromocresol Blue, 860 Bromocresol Blue TS, 850... 

A. Add 25 mL of 1 2 hydrochloric acid to about 1.5 g of sample, and dilute to 50 mL with water. Heat to effect complete solution then cool filter on a fine-porosity, sintered-glass crucible wash the precipitate with 2 100 hydrochloric acid, saving the filtrate for Identification Test B and dry the precipitate at 105°. Add 3 mL of water and 7 mL of 1 A sodium hydroxide to 400 mg of the dried precipitate, and stir until solution is complete. Add, dropwise, 2.7 A hydrochloric acid until the solution is just acid to litmus add 1 g of p-nitrobenzyl bromide and 10 mL of alcohol and reflux the mixture for 2 h. Cool, filter, and wash the precipitate with two small portions of a 2 1 alcohol water mixture, followed by two small portions of water. The precipitate, recrystallized from hot alcohol and dried at 105°, melts at about 152° (see Melting Range or Temperature, Appendix IIB). 

The selectivity of the test is quite limited, even compared to the specificity seen in the identification test for chlorides. In the identification three criteria have to be fulfilled to qualify for a positive reaction. The unknown should give a white (curdled) precipitate formed upon addition of silver nitrate, which is insoluble in dilute nitric acid but redissolves in ammonia. In the limit test 2.4.4. Chlorides any substance capable of giving a white or weakly colored precipitate in dilute nitric acid will give a response like chloride, and this should be remembered in case of an xmexpected result. For the sake of example the following ions and substances are capable of giving a false positive reaction bromide, iodide, bromate, iodate, sulfite, chlorate, oxalate, and benzoate. In addition to this a variety of more complex organic substances are likely to precipitate, for example, alkaloids. 

BP and EP recommend that for the bromide test, a sample solution has to be first acidified with dilute nitric acid, and silver nitrate solution is added to produce a curdled, pale yellow precipitate. This precipitate will dissolve with difficulty when suspended in a solution consisting of 2 ml of water and 1.5 ml of ammonia. Unlike BP and EP, USP employs a silver nitrate test for identification of bromide. In this test, addition of silver nitrate test solution to the solution of rocuronium bromide (1 part of rocuronium bromide in 100 parts of water) will produce a white precipitate which is insoluble in nitric acid and slightly soluble in 6N ammonium hydroxide. 

Identification An infrared absorption spectrum of a potassium bromide dispersion of Aspartame-Acesulfame Salt exhibits maxima only at the same wavelengths as those of a typical spectrum as shown in the section on Infrared Spectra, using the same test conditions as specified therein. 

It is apparent from the foregoing that a more specific method for the determination of xylan would be desirable. To this end, the determination of xylose, after acid hydrolysis of the polysaccharide material, has been attempted. Xylose may be oxidized to xylonic acid which can be precipitated with cadmium bromide as the double salt, but the precipitation is not quantitative. Xylose forms an insoluble, crystalline di-O-benzylidene dimethyl acetal which permits identification in the presence of other sugars, but the necessity for anhydrous reaction conditions precludes the adaptation of this method to ordinary analysis. AVise and Ratliff prepared this derivative of both d- and L-xylose, as well as analogous derivatives from other aromatic aldehydes, and concluded that, with either the di-O-benzylidene or the di-O-(p-isopropylbenzylidene) dimethyl acetal, an excellent, highly specific, qualitative test was available for d- or n-xylose. 

The bromine number is the number of grams of bromine that will react with 100 g of the sample under the test conditions. The magnitude of bromine number is an indication of the quantity of bromine-reactive constituents and is not an identification of constituents. It is used as a measure of aliphatic unsaturation in petroleum samples and percentage of olefins in petroleum distillates boiling up to approximately 315°C (600°F). In the test, a known weight of the sample dissolved in a specified solvent maintained at 0-5°C (32-41 °F) is titrated with standard bromide-bromate solution. Determination of the end point is method dependent. 

Qualitatively, these may be quickly detected by the Beilstein test for halogens a copper wire is heated in a gas burner until no color can be seen and the coil plunged into the acetic acid, then brought into the gas flame again. Any trace of green or blue-green flame shows the presence of halogen. The lower identification threshold is about 0.7 ppm for chloride, about 0.65 ppm for bromide, and about 0.55 for iodide. 

In the test, chloride is precipitated as silver chloride, and the precipitates reaction toward nitric acid and ammonia is used to rule out other silver precipitates. Since a very high number of elements and also organic substances give a precipitate with silver nitrate, the description below of selec-fivify is nof meanf to be conclusive. It mainly deals wito the other halogens and a few inorganic cations. Precipitation with silver nitrate is also used for the identification of iodide and bromide, and the difference between the tests of these is therefore dealf with in more detail. 

Cyclic nitramines such as RDX or cyclotetra-methylenetetranitramine (HMX) are widely used in military composites such as Composition B (TNT and RDX) and Composition C-4 (US) or PE-4 (British) and in commercial blasting explosives such as Semtex (a Czech-made mining explosive). HMX is present as a by-product in RDX made by the Bach-mann process and has applications in explosives to be used in high-temperature environments. Chemical tests for RDX include the J-Acid and thymol tests. A number of TLC systems for RDX and HMX have been reported. With adequate sample, IR identification of the pure material in a micro-potassium bromide pellet is simple. If a diamond anvil sample holder or microscope attachment is available, excellent spectra of pure samples of milligram size or even of single crystals are easily obtained. When HMX is observed in RDX-based explosives, its concentration may suggest the national origin of the explosive. 

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