Covalent compounds bromine

Many of the reactions of halogens can be considered as either oxidation or displacement reactions the redox potentials (Table 11.2) give a clear indication of their relative oxidising power in aqueous solution. Fluorine, chlorine and bromine have the ability to displace hydrogen from hydrocarbons, but in addition each halogen is able to displace other elements which are less electronegative than itself. Thus fluorine can displace all the other halogens from both ionic and covalent compounds, for example... 

The tetrahedral radii for first-row and second-row elements are identical with the normal single-bond covalent radii given in Table 7-2. For the heavier atoms there are small differences, amounting to 0.03 A for bromine and 0.05 A for iodine. It is possible that these differences are due to the difference in the nature of the bond orbitals in tetrahedral and normal covalent compounds. 

Elemental bromine is a diatomic molecule (Bt2). Bromine will combine with most other elements. Reaction with metallic elements leads to salts such as silver bromide (AgBr), in which the bromine atom has a — 1 charge and oxidation number. Bromine forms many interesting covalent compounds as well, including two oxides bromine (TV) oxide (Br02) and bromine... 

Write the molecular formula for each of the following covalent compounds (a) sulfur hexafluoride, (b) bromine pentafluoride, (c) disulfur dichloride, (d) tetrasulfur tetranitride... 

For covalent chlorine, bromine and iodine compounds the relaxation times of the halogen nuclei are extremely short and problems of sensitivity considerable even for pure liquids. Direct observations of NMR signals have therefore been reported only for chlorine compounds. Narrow signals are obtained when the nucleus is at a site of tetrahedral symmetry in covalent compounds (cf. Chapter 9). 

The earliest experimental observation of chlorine, bromine, and iodine NMR signals were achieved in the late 1940 s, first for the ions in aqueous solutions where the lines are relatively narrow (4-8). Early attempts to observe tJMR signals from covalent compounds were unsuccessful. The failure to observe bromine NMR spectra of liquid Br2 and CHBr was correctly interpreted by Pound (7) as due to very rapid quadrupole relaxation, which broadened the signals beyond detection. 

Halogens, Hydrogen Halides, and Other Covalent Halides. Most compounds containing Si—H bonds react very rapidly with the free halogens. An explosive reaction takes place when chlorine or bromine is allowed to react with SiH at room temperature, presumably forming halogenated silane derivatives (3). At lower temperatures, the reactions are moderated considerably, for example. 

MRH Bromine 1.21/91, carbon tetrachloride 2.89/83, chlorine 3.85/82 Silane burns in contact with bromine, chlorine or covalent chlorides (carbonyl chloride, antimony pentachloride, tin(IV) chloride, etc.) [1], Extreme caution is necessary when handling silane in systems with halogenated compounds, as a trace of free halogen may cause violent explosions [2],... 

An amino or hydroxy group facilitates 5-bromination even in aqueous solution. A -bromosuccinimide (NBS) and molecular bromine are the commonest reagents used. In uracils, cytosines, and barbituric acids, products of both addition and substitution can be identified in aqueous solution, and 5,5-dibromo products are common. In the bromination of uracils, addition products, including covalent hydrates, form rapidly, and the acid-catalyzed dehydration step to 5-bromouracils is much slower. Cytosine and related compounds behave similarly <1994HC(52)1, 1996CHEC-II(6)93>. 

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