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In organic chemistry, a radical-substitution reaction is a substitution reaction involving free radicals as a reactive intermediate. [1] The reaction always involves at least two steps, and possibly a third. In the first step called initiation (2,3), a free radical is created by homolysis.
Chain propagation: A radical reacts with a non-radical to produce a new radical species; Chain termination: Two radicals react with each other to create a non-radical species; In a free-radical addition, there are two chain propagation steps. In one, the adding radical attaches to a multiply-bonded precursor to give a radical with lesser bond ...
Radicals can undergo a disproportionation reaction through a radical elimination mechanism (See Fig. 1). Here a radical abstracts a hydrogen atom from another same radical to form two non-radical species: an alkane and an alkene. Radicals can also undergo an elimination reaction to generate a new radical as the leaving group.
Substitution reactions are of prime importance in organic chemistry. Substitution reactions in organic chemistry are classified either as electrophilic or nucleophilic depending upon the reagent involved, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical, and whether the substrate is ...
In the third type of substitution reaction, radical substitution, the attacking particle is a radical. [44] This process usually takes the form of a chain reaction, for example in the reaction of alkanes with halogens. In the first step, light or heat disintegrates the halogen-containing molecules producing radicals.
In polymer chemistry, there are several mechanisms by which a polymerization reaction can terminate depending on the mechanism and circumstances of the reaction. A method of termination that applies to all polymer reactions is the depletion of monomer. In chain growth polymerization, two growing chains can collide head to head causing the ...
In chemistry, hydrogen atom abstraction, or hydrogen atom transfer (HAT), refers to a class of chemical reactions where a hydrogen free radical (a neutral hydrogen atom) is removed from a substrate, another molecule. This process follows the general equation:
In organic chemistry, free-radical halogenation is a type of halogenation. This chemical reaction is typical of alkanes and alkyl-substituted aromatics under application of UV light. The reaction is used for the industrial synthesis of chloroform (CHCl 3), dichloromethane (CH 2 Cl 2), and hexachlorobutadiene. It proceeds by a free-radical chain ...