Bromine qualitative detection

Haslam et af have adopted the oxygen flask combustion technique to the qualitative detection in polymers of nitrogen, chlorine, bromine, iodine, fluorine, phosphorus and sulphur in amounts down to 0.25%, (see Method 104). 

The reaction with bromine is very rapid and is easily carried out at room temperature, although the reaction is reversible under some conditions. In the case of bromine, an alkene-Br2 complex has been detected in at least one case. Bromine is often used as a test, qualitative or quantitative, for unsaturation. The vast majority of double bonds can be successfully brominated. Even when aldehyde, ketone, amine, so on functions are present in the molecule, they do not interfere, since the reaction with double bonds is faster. 

Thin-Layer Chromatography. Thin-layer chromatography was used for many of the compounds which are of interest for either qualitative or quantative analysis. These techniques were used primarily as screening methods to supplement other analytical methods. For some brominated compounds such as TRIS, the detection system reported by Hahn (9) was applicable. This method is based upon the reaction of fluorescein with elemental bromine released through peroxide oxidation. An evaluation in our laboratory of this detection system indicated that semi-quantitative results... 

Bromine and bromides can be detected qualitatively by a number of methods. In higher concentrations bromine forms colored solutions in solvents such as carbon tetrachloride [56-23-5] and carbon disulfide [75-15-0]. Bromine reacts with yellow disodium fluorescein [518 47-8] to form red disodium tetrabromofluorescein (eosin) [548-26-5], C20H6Br4Na2O5. As little as 0.3 Jg of bromide can be detected and chlorides do not interfere (56). Bromine reacts with platinum sulfate [7446-29-9], Pt(S04)2, solution to form red to brown crystals of potassium hexabromoplatinate [16920-93-7], K PtBr (57). 

Central ite 1 Analytical Procedures. Centr 1 can be detected by various colorimetric tests, such as described in Refs 1,6,12,24, 28 Sc 33. Some other qualitative tests are given in Ref 13. Quantitative detns of Centr 1 by bromination methods are described in Refs 4,5,7,9,10,14,16,17,20,27,34 Sc 35. Chromatographic and spectrophotometric methods are found in Refs-11,15,18,21,22,23,24, 29,30,32 Sc 33. Other quantitative methods, including polarographic, are in Refs 2,7a,20a,25, 26,27 Sc 30. X-ray diffraction spectra data are given in Ref 19. Detns of stabilizing action of Centr 1 by methods of Taliani and Thomas are discussed in Refs 3 8... 

JCS(B)43], which is qualitatively consistent with the reaction selectivi-ties. The first two factors afforded cr+2 values of -0.94 and -0.84, respectively. No addition was detected and in each bromination the proportion of the 3-isomer was less than 1%. 

In addition to the seven organic products mentioned above, ozonoly-sis of 23 also produced considerable amounts of free bromine, which was qualitatively and quantitatively detected by its addition to 2,3-dimethyl-2-butene and subsequent analysis of the resulting dibromide. 

When aldehydes are prepared by ozonolysis, exactly the correct amount of ozone must be added, because excess ozone converts aldehydes to acids and peracids. In addition, alcohols, ethers, double bonds, or other functional groups present in the molecule may be attacked. This brings up the problem of determining when to stop the ozonolysis reaction. The theoretical amount of ozone may be added, but several cases are recorded in which more than one molar equivalent of ozone is required to cleave one double bond. One may stop when ozone appears in the effluent gas from the reactor. However, preliminary experiments have shown that at this low temperature ozone begins to overflow very soon after the reaction has started. A more useful method has been to stop the ozonolysis when the reaction mixture no longer shows unsaturation. This may be detected qualitatively by the use of bromine in carbon tetrachloride, tetranitromethane, etc. An infrared method makes it possible to follow quantitatively the rate of disappearance of trans double bonds and to locate the end point more exactly. The method was applied to the ozonolysis of stigmastadienone with good results. 

An additional technique that has been found useful in analysis of the composition of polymers and blends is liquid chromatography. Pasch and Rode used the critical point of adsorption of the least polar component of a blend to determine the liquid chromatographic conditions for separating blends of polymethacrylates into components (50). High pressure liquid chromatography (HPLC) in combination with mass spectroscopy was used to analyze the components of an epoxy resin (51). HPLC has also been used with a precipitation-redissolution technique to separate polymer molecular weights for several polymers as a shorter technique compared to SEC (52). Reverse-phase liquid chromatography with UV detection was useful in qualitative determination of brominated flame retardants in polymeric waste materials (53). 

GC Bromination of the aromatic ring system to yield the corresponding bromo derivatives The derivatization method is very easy to perform Certain analytes are not detected as intact brominated molecules because of the reported cracking they undergo under the bromination conditions and only qualitative conclusions can be drawn Dados et al. (2004)... 

Traditional chemical methods are currently used in the characterization of fatty acids neutralization values permit the calculation of the mean molecular weight and a series of values (for instance, iodine, thiocyanogen, and hydrogenation values) for determining the degree of unsaturation. A complete analysis of fatty acid mixtures would nevertheless require the qualitative and quantitative detection of all the fatty acids (Fontell et al., 1960). Such methods as crystallization of salts and bromine adduct formation have been used to some extent. Nowadays, less conventional methods have found wide... 

The presence of BujSn and BujSn species in chloroform or benzene extracts from hydrobromic acid acidified non saline waters can be demonstrated qualitatively by thin layer chromatography on Eastman chromatogram sheets using hexane-acetone-acetic acid 40 4 1 as an eluent [123]. After spraying with a 0.17o dithizone solution in chloroform, BujSn species are visualised as a yellow spot (R, value 0.75) and BUjSn species as a red spot (R, value of 0.50). The detection limit is improved by loping the thin layer strip for 10s in bromine vapour after elution. Bromine breaks carbon-tin bonds, and both BujSn and BujSn species are now detected as red spots after spraying. The detection limit after bromination is about 0 5pg tin per spot. 

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