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NBS will react with alkenes 1 in aqueous solvents to give bromohydrins 2. The preferred conditions are the portionwise addition of NBS to a solution of the alkene in 50% aqueous DMSO, DME, THF, or tert-butanol at 0 °C. [3] Formation of a bromonium ion and immediate attack by water gives strong Markovnikov addition and anti stereochemical ...
Bromine water, Br 2. Bromine water is an oxidizing, intense brown mixture containing diatomic bromine (Br 2) dissolved in water (H 2 O). [1] It is often used as a reactive in chemical assays of recognition for substances which react with bromine in an aqueous environment with the halogenation mechanism, mainly unsaturated carbon compounds (carbon compounds with 1 or more double or triple bond(s)).
The same is true when an alkene reacts with water in an addition reaction to form an alcohol which involve formation of carbocations. The hydroxyl group (OH) bonds to the carbon that has the greater number of carbon–carbon bonds, while the hydrogen bonds to the carbon on the other end of the double bond, that has more carbon–hydrogen bonds.
Industrially, it is mainly produced by the reaction of hydrogen gas with bromine gas at 200–400 °C with a platinum catalyst. However, reduction of bromine with red phosphorus is a more practical way to produce hydrogen bromide in the laboratory: [2] 2 P + 6 H 2 O + 3 Br 2 → 6 HBr + 2 H 3 PO 3 H 3 PO 3 + H 2 O + Br 2 → 2 HBr + H 3 PO 4
Reaction is slower with alkynes than alkenes. [3]: 750 In the paradigmatic example, hydrogen bromide radicalyzes to monatomic bromine. These bromine atoms add to an alkene at the most accessible site, to give a bromoalkyl radical, with the radical on the more substituted carbon.
A halogen addition reaction is a simple organic reaction where a halogen molecule is added to the carbon–carbon double bond of an alkene functional group. [1] The general chemical formula of the halogen addition reaction is: C=C + X 2 → X−C−C−X (X represents the halogens bromine or chlorine, and in this case, a solvent could be CH 2 ...
Illustrative of the bromination of an alkene is the route to the anesthetic halothane from trichloroethylene: [6] Iodination and bromination can be effected by the addition of iodine and bromine to alkenes. The reaction, which conveniently proceeds with the discharge of the color of I 2 and Br 2, is the basis of the analytical method.
The Wittig reaction involves reaction of an aldehyde or ketone with a Wittig reagent (or phosphorane) of the type Ph 3 P=CHR to produce an alkene and Ph 3 P=O. The Wittig reagent is itself prepared easily from triphenylphosphine and an alkyl halide.