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The
Wohl-Ziegler reaction
is a
chemical reactionA chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
that involves the allylic or benzylic bromination of
hydrocarbonIn organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
s using an
N-bromoimide and a
radical initiatorIn chemistry, radical initiators are substances that can produce radical species under mild conditions and promote radical reactions . These substances generally possess weak bonds—bonds that have small bond dissociation energies. Radical initiators are utilized in industrial processes such...
.
Best yields are achieved with
N-bromosuccinimideN-Bromosuccinimide or NBS is a chemical reagent which is used in radical substitution and electrophilic addition reactions in organic chemistry. NBS can be considered a convenient source of cationic bromine.-Preparation:...
in
carbon tetrachlorideCarbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
solvent. Several reviews have been published.
In a typical setup a stoichiometric amount of
N-bromosuccinimide solution and a small quantity of initiator are added to a solution of the substrate in CCl
4, and the reaction mixture is stirred and heated to the boiling point. Initiation of the reaction is indicated by more vigorous boiling; sometimes the heat source may need to be removed. Once all
N-bromosuccinimide (which is denser than the solvent) has been converted to
succinimideSuccinimide is a cyclic imide with the formula C4H5NO2. It is used in a variety of organic syntheses, as well as in some industrial silver plating processes.-Succinimides:...
(which floats on top) the reaction has finished.