5) Radical Halogenation of Alkanes + features of halogenation rxns

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What is an alkyl?

An alkane missing 1 hydrogen; this allows a substituent to attach

What is a halide?

A halogen atom bonded to another element, typically carbon

What is an alkyl halide?

Where a halogen is bonded to a carbon atom in an alkyl group

We use what halogens for radical halogenation?

Cl2 and Br2

Why don’t we use F or I atoms?

F reacts too violently and I reacts too slowly

What is radical halogenation?

A halogen (like Cl₂ or Br₂) replaces a hydrogen atom in an alkane

Mechanism of radical halogenation def

A step by step reaction of a halogen replacing a hydrogen atom

Alkanes with multiple types of C–H bonds (1°, 2° carbons) create?

a mixture of alkyl halide products

mixture of alkyl halide products def

a halogen has replaced a hydrogen on different carbon atoms (primary, secondary, etc) in the molecule

What are C-H bonds?

the alkane (saturated hydrocarbon chain, contains only C and H)

If the halogen is added in excess

multiple substitutions will occur, can connect to primary, secondary carbons and so on

If the alkane is in excess

monohalogenation will occur

What is monohalogenation?

Only one hydrogen atom in the alkane is replaced by one halogen atom

What is Initiation?

Two radicals are formed by homolysis of a sigma bond

What is propagation?

A radical reacts with another reactant to form a new sigma bond and another radical

What is termination?

Two radicals react to form a stable bond, which stops the reaction.