Interhalogens properties

Two approaches that have been investigated recently for disinfection are mixtures of bromine and chlorine, and mixtures containing bromide or iodide salts. Some evidence exists that mixtures of bromine and chlorine have superior germicidal properties than either halogen alone. It is believed that the increased bacterial activity of these mixtures can be attributed to the attacks by bromine on sites other than those affected by chlorine. The oxidation of bromide or iodide salts can be used to prepare interhalogen compounds or the hypollalous acid in accordance with the following reaction ... 

The physical properties of the interhalogens are intermediate between those of their parent halogens. Trends in the chemistry of the interhalogen fluorides can be related to the decrease in bond dissociation energy as the central halogen atom becomes heavier. The fluorides of the heavier halogens are all very reactive bromine trifluoride gas is so reactive that even asbestos burns in it. 

The interhalogens have properties intermediate between those of the constituent halogens. Nonmetals form covalent halides metals tend to form ionic halides. The oxoacids of chlorine are all oxidizing agents both acidity and oxidizing strength of oxoacids increase as the oxidation number of the halogen increases. 

From these monomer properties alone it is not quite clear how the trends in the interaction strength with a fixed given acceptor B will develop. For the X2 molecules the polarizabilities rise in the series F2, CI2, and Br2. The dipole moments of the interhalogens XY decrease in the series C1F, BrF, and BrCl, whereas the polarizabilities increase in this series. 

Lagowski, J. J., Ed., The Chemistry of Non-Aqueous Solvents, Academic, New York. This series contains detailed accounts of the purification, properties, and handling of some major solvents Vol. 2(1967), hydrogen halides, amides, and ammonia Vol. 3(1970), sulfur dioxide and acetic acid Vol. 4 (1976), tetramethylurea, cyclic carbonates, and sulfolane Vol. 5A (1978), tri-fluoroacetic acid, hafosuffuric acids, interhalogens, inorganic halides and oxyhalides. 

As a general rule, the properties of interhalogen compounds are intermediate between those of their parent elements. For example, IC1 is a red solid that melts near room temperature, and BrF is a brownish gas that condenses to a liquid near room temperature. All six possible diatomic interhalogen compounds are known, and all act as strong oxidizing agents in redox reactions. 

Table 11.1 Major Interhalogen Compounds Compound Name and Formula Physical Properties... 

The halogens react with each other to form binary interhalogen compounds XY, XY3, XY5 and XY7, where X is the heavier halogen. A few ternary compounds are also known, e.g., IFCI2 and IF2CI. All interhalogen compounds contain an even number of halogen atoms. Table 17.2.1 lists the physical properties of some XYm compounds. 

XY All six possible diatomic interhalogen compounds between F, Cl, Br and I are known, but IF is unstable, and BrCl cannot be isolated free from Br2 and CI2. In general, the diatomic interhalogens exhibit properties intermediate... 

Table 17.2.1. Physical properties of some interhalogen compounds...

The interhalogens, particularly the halogen fluorides, are chemically very reactive materials and hydrolyze easily. The handling and manipulation of these, their derivatives, and cationic or anionic species have to be performed using the safety precautions customary in fluorine chemistry (exclusion of moisture and air, and in vacuum lines constracted from materials that are resistant to fluorine). The properties of the interhalogens are intermediate between those of their parent halogens, and some physical properties are summarized in Table 4. 

---