Halogenations sodium periodate

Identify the oxidation number of the halogen atoms in (a) iodine heptafluoride (b) sodium periodate (c) hypobromous acid (d) sodium chlorite. 

Sodium periodate or positive halogenanting species such as A-chlorosuccinimide and f-bntyl hypochlorite" are nsefnl oxidizing reagents. 

Oxidation of the heterocycles with common reagents such as MCPBA, sodium periodate or hydrogen peroxide cleanly affords the sulfoxides and sulfones, and it is clear that the sulfur atom is the principal centre of reaction for electrophiles. While the sulfone is a quite inert functionality, the sulfoxides may be reduced to the sulfides with phosphorus pen-tasulfide as for the tetrahydro systems (78CJC1423). Positive halogen sources likewise react at sulfur, and the intermediate sulfonium halide rearranges, usually by 1,2-shift to the a-halo product. 

The sodium periodate-mediated oxidation of alkali halides is a useful method to accomplish the halogenation of aromatic compounds. Accordingly, NaCl is successfully employed as a chlorine source for the chlorination of various aromatic compounds, although mixtures of regioisomers are sometimes obtained on the other hand, the related sodium periodate-mediated bromina-tion reaction, which uses lithium bromide or sodium bromide as halogen source, affords the expected brominated products in a regioselective fashion (eq 33). ... 

Ionization lithium, 267 magnesium, 270 sodium, 270 Ionization energy, 267 alkaline earths, 379 and atomic number, 268 and ihe periodic table, 267 and valence electrons, 269 halogens, 353 measurement of, 268 successive, 269 table of, 268 trends, 268... 

The first column of the periodic table, Group 1, contains elements that are soft, shiny solids. These alkali metals include lithium, sodium, potassium, mbidium, and cesium. At the other end of the table, fluorine, chlorine, bromine, iodine, and astatine appear in the next-to-last column. These are the halogens, or Group 17 elements. These four elements exist as diatomic molecules, so their formulas have the form X2 A sample of chlorine appears in Figure EV. Each alkali metal combines with any of the halogens in a 1 1 ratio to form a white crystalline solid. The general formula of these compounds s, AX, where A represents the alkali metal and X represents the halogen A X = N a C 1, LiBr, CsBr, KI, etc.). 

Some of the investigations carried out in the first half of the twentieth century were related to CL associated with thermal decomposition of aromatic cyclic peroxides [75, 76] and the extremely low-level ultraviolet emission produced in different reaction systems such as neutralization and redox reactions involving oxidants (permanganate, halogens, and chromic acid in combination with oxalates, glucose, or bisulfite) [77], In this period some papers appeared in which the bright luminescence emitted when alkali metals were exposed to oxygen was reported. The phenomenon was described for derivatives of zinc [78], boron [79], and sodium, potassium, and aluminum [80]. 

Hence as we go down the halogen column of the Periodic Table the atoms become less electronegative. This is because of the increasingly effective shielding of the charge on the nucleus by inner electrons. Alkali-metal atoms, on the other hand, have a great tendency to lose their outer electrons and therefore have a low electronegativity, as evinced by sodium (0.9) and potassium (0.8). 

The halogenation reaction appears to be quite rapid therefore the time of stirring is not critical but probably should not be prolonged beyond 4 hours. The submitters used this time interval to prepare the sodium methoxide solution, and the actual time lapse depended upon the time required to prepare this solution. The solution of N,N-dichloro-a-phenylethylamine should be clear yellow after the stirring period. A turbid solution or one containing a precipitate usually indicates a poor sample of terf-butyl hypochlorite. 

The treatment with sodium ethylate removed any traces of side chain halogen derivatives. Some care has to be exercised at this point as the solution may foam at the beginning of the heating period. 

Periodic Properties movie Sodium and Potassium in Water movie and Physical Properties of the Halogens movie... 

Elements having similar electron orbital configurations tend to display similar properties. Because of the way the periodic table is organized, elements that tend to behave the same way can be found in the vertical columns. For instance, the halogen elements, near the right edge of the table, combine in the same ways with other elements. Thus, chlorine, bromine, and fluorine readily form compounds with sodium, calcium, and other similar elements. 

Approximately 0.3 g. of sample, accurately weighed, is added to 100 ml. of 5 % aqueous sodium hydroxide contained in a beaker. Three grams of the nickel-aluminum alloy is added in three or four portions over a period of 10 minutes. When the reaction has subsided, the mixture is heated on a steam bath for 1 hour and then filtered, the residue being carefully washed. An aliquot portion of the filtrate may now be analyzed for halogens by any standard procedure. Ethanol may be used to facilitate the reduction of alkali insoluble compounds. 

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