Compounds of Fluorine, Chlorine, Bromine and Iodine

The Halides.—Compounds of fluorine, chlorine, bromine, and iodine are thus named. They fall into classes when the elements are arranged according to the periodic system. Taking the chlorides as typical of the halides, we have the following table —... 

The preparation of organic compounds containing fluorine, chlorine, bromine, and iodine can be accomplished by a variety of methods. The conditions and procedures differ, not only for each member of the halogen family but also with the type and structure of the compound undergoing treatment. 

The most important of the halogenated derivatives of acetic acid is chloroacetic acid. Fluorine, chlorine, bromine, and iodine derivatives are all known, as are mixed halogenated acids. For a discussion of the fluorine derivatives see Fluorine compounds, organic. 

Synthetic procedures are available for the preparation of fluoro, chloro, bromo and iodo compounds from the corresponding lithio derivatives. Perchloryl fluoride (FCIO3), N-chlorosuccinimide, bromine and iodine are examples of reagents which can be used to introduce fluorine, chlorine, bromine and iodine, respectively. 

Fluorine, chlorine, bromine, and iodine react with H S to form the corresponding halogen acid. Metal sullides are formed when H S is passed inlo solutions of the heavy metals, such as Ag. Ph. Cu. and Mn. This rcaelion is responsible lor the tarnishing of Ag and is the hasis for the separation of these metals in classical wet qualitative analytical methods. Hydrogen sullide reacts with many organic compounds. 

Halidei. Minerals composed of compounds of metals with fluorine, chlorine, bromine, and iodine. 

Some nonmetals can replace another nonmetal from a compound, too. This replacement is usually limited to the nonmetals called the halogens (fluorine, chlorine, bromine, and iodine). The halogens can be found in Group 17 on the periodic table. The activity of the halogens decreases as you go down Group 17. Fluorine is the most active and iodine is the least. 

The elemental halogens — fluorine, chlorine, bromine, and iodine — are all toxic. Both fluorine and chlorine are highly corrosive gases that are very damaging to exposed tissue. These elements are chemically and toxicologically similar to many of their compounds, such as the interhalogen compounds, discussed in Chapter 11. The toxicities of halogen compounds are discussed in the next two sections. 

Chemical formulas identify compounds, ions, or molecules. The formula implies that the atoms are held together by some kind(s) of chemical bond(s). When they are not combined with other elements, hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine exist as diatomic molecules (Figure 5.2). 

The noble gases are immediately followed in the periodic table by the alkali metals, which are the elements with the most pronounced metallic properties, and are immediately preceded by the elements which differ the most from the metals. These non-metallic elements, in group VII of the periodic table, are fluorine, chlorine, bromine, and iodine. Because many of their compounds are salts they are called the halogens (from the Greek words meaning salt-producer). 

Similarly, the elements fluorine, chlorine, bromine, and iodine can combine with sodium in a 1 1 ratio to form NaF, NaCl, NaBr, and NaL These compounds are also white solids that can dissolve in water to form solutions that conduct electricity These examples show that even though each element is different, groups of them have much in common. 

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