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A hydrohalogenation reaction is the electrophilic addition of hydrogen halides like hydrogen chloride or hydrogen bromide to alkenes to yield the corresponding haloalkanes. [ 1 ] [ 2 ] [ 3 ] If the two carbon atoms at the double bond are linked to a different number of hydrogen atoms, the halogen is found preferentially at the carbon with fewer ...
Dehydrohalogenation to give an alkene. In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications.
The Boord olefin synthesis is an organic reaction forming alkenes from ethers carrying a halogen atom 2 carbons removed from the oxygen atom (β-halo-ethers) using a metal such as magnesium or zinc. The reaction, discovered by Cecil E. Boord in 1930 [ 1 ] is a classic named reaction with high yields and broad scope.
The addition of halogens to alkenes proceeds via intermediate halonium ions. In special cases, such intermediates have been isolated. [5] Bromination is more selective than chlorination because the reaction is less exothermic. Illustrative of the bromination of an alkene is the route to the anesthetic halothane from trichloroethylene: [6]
The reaction mechanism for an alkene bromination can be described as follows. In the first step of the reaction, a bromine molecule approaches the electron-rich alkene carbon–carbon double bond. The bromine atom closer to the bond takes on a partial positive charge as its electrons are repelled by the electrons of the double bond.
Tetrafluoroethane (a haloalkane) is a colorless liquid that boils well below room temperature (as seen here) and can be extracted from common canned air canisters by simply inverting them during use. The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents. [1]
The negative charge placed on this position (formally a carbanion) is transferred to the halogen residing on the other α-position in a nucleophilic displacement temporarily forming a three-membered cyclic sulfone. This intermediate is unstable and releases sulfur dioxide to form the alkene. Mixtures of cis isomer and trans isomer are usually ...
In chemistry, the haloform reaction (also referred to as the Lieben haloform reaction) is a chemical reaction in which a haloform (CHX 3, where X is a halogen) is produced by the exhaustive halogenation of an acetyl group (R−C(=O)CH 3, where R can be either a hydrogen atom, an alkyl or an aryl group), in the presence of a base.