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Organobromine chemistry is the study of the synthesis and properties of organobromine compounds, also called organobromides, [1] which are organic compounds that contain carbon bonded to bromine. The most pervasive is the naturally produced bromomethane .
Most 1-bromoalkanes are prepared by free-radical addition of hydrogen bromide to the 1-alkene, which is 1-pentene in the case of 1-bromopentane. These conditions lead to anti-Markovnikov addition, giving the 1-bromo derivative. [2] It is also formed by the reaction of 1-pentanol with hydrogen bromide.
Tetrasubstituted alkenes add 9-BBN at elevated temperature. Hydroboration of alkenes with 9-BBN proceeds with excellent regioselectivity. It is more sensitive to steric differences than Sia 2 BH, perhaps because of it rigid C 8 backbone. 9-BBN is more reactive towards alkenes than alkynes. [13]
Hydroboration of 1,2-disubstituted alkenes, such as a cis or trans olefin, produces generally a mixture of the two organoboranes of comparable amounts, even if the steric properties of the substituents are very different. For such 1,2-disubstituted olefins, regioselectivity can be observed only when one of the two substituents is a phenyl ring.
Wittig reactions are most commonly used to convert aldehydes and ketones to alkenes. [1] [2] [3] Most often, the Wittig reaction is used to introduce a methylene group using methylenetriphenylphosphorane (Ph 3 P=CH 2). Using this reagent, even a sterically hindered ketone such as camphor can be converted to its methylene derivative.
The model is named after Michael J. S. Dewar, [1] Joseph Chatt and L. A. Duncanson. [2] [3] The alkene donates electron density into a π-acid metal d-orbital from a π-symmetry bonding orbital between the carbon atoms. The metal donates electrons back from a (different) filled d-orbital into the empty π * antibonding orbital. Both of these ...
Most 2-bromoalkanes are prepared by addition of hydrogen bromide to the 1-alkene. Markovnikov addition proceeds in the absence of free-radicals, i.e. give the 2-bromo derivatives. [ 2 ]