HALOALKANES

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CHAPTER 15

• HALOALKANES

- Edited by KMPh
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Learning outcomes

• Give the general formula of haloalkane.
• Draw the structures, classify and name 1?, 2? and
  3? haloalkanes according to the IUPAC
  nomenclature.
• Describe haloalkanes contain polar bond, carbon
  bearing the halogen is susceptible to
  nucleophilic attack.

V1 Intro
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Introduction

• Haloalkanes or alkyl halides
• - compounds that contains halogen atom as
  functional group.
• - In alkyl halides, halogen atoms are bonded to
  sp3 hybridized carbon atom.
• General formula R-X
• or CnH2n1X (acyclic)
• or CnH2n-1X (cyclic)
  
• where X halogen atom (F,
  Cl, Br or I)

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Classification of Haloalkanes
Haloalkanes are classified based on the carbon
atom to which the halogen is directly attached.
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(No Transcript)
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Example

• Classify the following haloalkanes

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IUPAC Nomenclature

• Haloalkanes are named as alkanes with halogen as
  substituents.
• Locate and number the parent chain from the
  direction that gives the substituent encountered
  first the lower number.
• Show halogen substituents by the prefixes
  flouro-, chloro-, bromo- and iodo-, and list them
  in alphabetical order along with other
  substituents.

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Example

• i.
• ii.

2-bromobutane
1-bromo-3-chloro-4-methylhexane
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Example

• iii.
• iv.

4-(2-flouroethyl)heptane
2-chloro-1,1-dimethylcyclopentane
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Example

• v. vi.
• vii.

4-bromocyclohexene
(chloromethyl)benzene
2-chlorotoluene
Video 2 (name class)
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Structure of Haloalkane

• Alkyl halides are polarized at the carbon-halide
  bond, making the carbon electrophilic
• The polar C X bond causes the carbon bearing
  the halogen is susceptible to nucleophilic attack.

d
d-
electrophilic site
electronegative halogen polarizes C-X bond
?-
?
Nu - attack at positive center
Video 3(Physical Properties)
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Substitution Reactions
?
?-

• As a result from Nu- attack at electrophilic
  C?, the C-X bond breaks heterolytically and X-
  leaves.
• The group replacing X- is a nucleophile.
• Haloalkanes are reactive and undergo nucleophilic
  substitution.

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Nucleophilic Substitution Reaction
Heterolysis cleavage
Leaving group