Halogens Group preparation

The self-extinguishing characteristics of the chlorine-containing resins are improved by incorporation of antimony oxide but this approach is not possible where translucent sheet is required. As an alternative to chlorine-based systems a number of bromine-containing resins have been prepared and, whilst claimed to be more effective, are not currently widely used. It is probably true to say that fire-retarding additives are used more commonly than polymers containing halogen groupings. 

Dissolve SIAB (Thermo Fisher) in DMSO at a concentration of 1.4mg/ml. Prepare fresh and protect from light to avoid breakdown of the active halogen group. 

Replacement of diazonium groups by halide is a valuable alternative to direct halogenation for preparation of aryl halides. Aryl bromides and chlorides are usually prepared by reaction of aryl diazonium salts with the appropriate Cu(I) salt, a process which is known as the Sandmeyer reaction. Under the classic conditions, the diazonium salt is added to a hot acidic solution of the cuprous halide.92 The Sandmeyer reaction is formulated as proceeding by an oxidative addition reaction of the diazonium ion with Cu(I) and halide transfer from the Cu(III) intermediate. 

Compounds XXI were characterized as stable tetraphenylboratc salts, which are thought to be a type of stibonium that contains Fe—Sb compounds containing halogen groups bonded to the antimony atom were prepared recently by the reaction of [Cp(CO)2Fe3i or Cp(CO)2FeNa with SbX3 (58, 59). 

W. E. Parham, C. K. Bradsher, Aromatic Organolithium Reagents Bearing Electrophilic Groups. Preparation by Halogen-Lithium Exchange, Acc. Chem. Res. 1982, 15, 300. 

Introduction. The diazo group, N2X, is easily replaced by a number of other functional groups, such as OH, Cl, Br, I and CN. This affords a convenient method for the preparation of such derivatives as cannot be obtained by other methods except with great difficulty. The replacement of N2X by a halogen group is accomplished by heating the solution of diazonium salt with cuprous halide (Sandmeyer reaction) or with finely divided copper (Gatterman reaction). In the preparation of iodides the catalytic effect of copper is not required it is necessary only to pour the diazonium salt into a solution of potassium iodide and then to acidify the solution ... 

In the series of dihalopyridazines the majority of transformations were carried out with 3,6-dichloropyridazines. Various groups could be attached through halogen exchange to the pyridazine nucleus with formation of a C-C bond. Examples include a reactive methyl group (preparation of pyri-... 

The dichlorostibines containing an amino-group together with an hydroxyl or halogen grouping are prepared by the reduction of the corresponding mtro-acids. 

In the halogen group, like in other groups of the periodic table, the heavier elements present more metallic and electropositive properties. It is therefore no wonder that the early observed spedes vdiidi were easiest to be prepared and identified were those containing iodine only. Iodine most readily releases an electron thus stsibilizing iodine cations. In the early studies it was assumed that the iodine cation exists as a mono-atomic one -I. But in later studies this assumption could not be confirmed and it was proven that no monoatomic halogen cations exist instead only polyatomic ones, such as I3,12 were identified. These earlier studies were reviewed by Arotsky and Symons ), whereas the later critics were included in the review by Gillespie and Mor-ton ) and therefore will not be repeated here. 

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