Dihalidien
Dihalidien, often referred to as dihalides, are chemical compounds that contain two halogen atoms, typically fluorine, chlorine, bromine, or iodine, in their structure. They are commonly categorized by how the halogen substituents are arranged on the carbon framework: 1,1-dihalides (geminal dihalides), where both halogens sit on the same carbon, and 1,2-dihalides (vicinal dihalides), where the halogens are on adjacent carbons. Examples of geminal dihalides include dichloromethane (CH2Cl2) and dibromomethane (CH2Br2). Examples of vicinal dihalides include 1,2-dichloroethane (Cl-CH2-CH2-Cl) and 1,2-dibromoethane (Br-CH2-CH2-Br). Inorganic dihalides form MX2 compounds such as iron(II) chloride (FeCl2) and zinc chloride (ZnCl2).
Dihalides display a range of properties depending on whether they are organic or inorganic. Organic dihalides
Preparation and typical reactions vary with type. Organic dihalides are usually prepared by halogenation of hydrocarbons:
See also: geminal dihalides, vicinal dihalides, metal dihalides.