HaloalkaneThe haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalkanes are widely used commercially. They are used as flame retardants, fire extinguishants, refrigerants, propellants, solvents, and pharmaceuticals. Subsequent to the widespread use in commerce, many halocarbons have also been shown to be serious pollutants and toxins.
IodineIodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a violet gas at . The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek Ιώδης 'violet-coloured'. Iodine occurs in many oxidation states, including iodide (I−), iodate (IO3-), and the various periodate anions.
Hydrogen fluorideHydrogen fluoride (fluorane) is an inorganic compound with chemical formula . It is a very poisonous, colorless gas or liquid that dissolves in water to yield an aqueous solution termed hydrofluoric acid. It is the principal industrial source of fluorine, often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers, e.g. polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as a component of superacids.
FluorideFluoride (ˈflʊəraɪd,_ˈflɔr-) is an inorganic, monatomic anion of fluorine, with the chemical formula F− (also written [F]−), whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin.
Hydrogen halideIn chemistry, hydrogen halides (hydrohalic acids when in the aqueous phase) are diatomic, inorganic compounds that function as Arrhenius acids. The formula is HX where X is one of the halogens: fluorine, chlorine, bromine, iodine, or astatine. All known hydrogen halides are gases at Standard Temperature and Pressure. The hydrogen halides are diatomic molecules with no tendency to ionize in the gas phase (although liquified hydrogen fluoride is a polar solvent somewhat similar to water).
Iodine deficiencyIodine deficiency is a lack of the trace element iodine, an essential nutrient in the diet. It may result in metabolic problems such as goiter, sometimes as an endemic goiter as well as congenital iodine deficiency syndrome due to untreated congenital hypothyroidism, which results in developmental delays and other health problems. Iodine deficiency is an important global health issue, especially for fertile and pregnant women. It is also a preventable cause of intellectual disability.
Potassium fluoridePotassium fluoride is the chemical compound with the formula KF. After hydrogen fluoride, KF is the primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide salt and occurs naturally as the rare mineral carobbiite. Solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective. Potassium fluoride is prepared by reacting potassium carbonate with hydrofluoric acid. Evaporation of the solution forms crystals of potassium bifluoride.
N-BromosuccinimideN-Bromosuccinimide or NBS is a chemical reagent used in radical substitution, electrophilic addition, and electrophilic substitution reactions in organic chemistry. NBS can be a convenient source of Br•, the bromine radical. NBS is commercially available. It can also be synthesized in the laboratory. To do so, sodium hydroxide and bromine are added to an ice-water solution of succinimide. The NBS product precipitates and can be collected by filtration. Crude NBS gives better yield in the Wohl-Ziegler reaction.
Fluoride toxicityFluoride toxicity is a condition in which there are elevated levels of the fluoride ion in the body. Although fluoride is safe for dental health at low concentrations, sustained consumption of large amounts of soluble fluoride salts is dangerous. Referring to a common salt of fluoride, sodium fluoride (NaF), the lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg elemental fluoride/kg body weight). Ingestion of fluoride can produce gastrointestinal discomfort at doses at least 15 to 20 times lower (0.
HalogenationIn chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, drugs. This kind of conversion is in fact so common that a comprehensive overview is challenging. This article mainly deals with halogenation using elemental halogens (). Halides are also commonly introduced using salts of the halides and halogen acids.
