C 10 J

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C 10 J Organic Chemistry
Dr. W. Gallimore winklet.gallimore_at_uwimona.edu.jm
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Organic Chemistry The chemistry of compounds of
Carbon

• Almost all reactions in living matter involve
• Organic Chemistry
• Major constituents of living matter
• Protein, DNA, carbohydrates

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• Other Organic substances of importance include
• Gasoline
• Clothes (e.g. cotton, synthetic fibres)
• Medicines e.g. aspirin

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Research in Organic Chemistry

• Making Molecules (Synthesis)
• Changing the Structures of Molecules
  (Transformations Biotransformations)
• Discovering New Molecules (Natural Products
  Chemistry)

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Part 1 Course Outline

• Describe the structure and bonding in alkanes,
  alkenes and alkynes in terms of the hybridization
  states of carbon
• Represent alkanes, alkenes and alkynes as dash
  formulae, condensed formulae, and bond-line
  drawings.
• Name acyclic and cyclic alkanes, alkenes and
  alkynes using the IUPAC system of nomenclature.
• Represent constitutional isomers of hydrocarbons.
• Represent and name geometric isomers of alkenes
  using the cis/trans and E/Z systems.
• Carry out conformational analysis of simple
  alkanes with the aid of sawhorse and Newman
  projections.
• Devise syntheses of alkanes, alkenes and alkynes
  using the methods described in the syllabus.

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Lecture Outline

• Bonding in Organic Compounds
• Ionic and covalent bonding
• Structure and bonding in alkanes, alkenes and
  alkynes
• Hybridization in carbon

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Bonding in Compounds

• Ionic and Covalent Bonding
• Ionic bond - Formed by electron transfer
• Covalent bond
• Involves the sharing of electrons

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Bonding in Organic Compounds

• Carbon atoms are able to share electrons not only
  with different elements but also with other
  carbon atoms it is possible for millions of
  organic compounds to exist
• forms covalent bonds with other atoms (electrons
  shared)
• Bonding pairs are represented by lines

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Structure and Bonding

• Electrons are concentrated in certain regions of
  space around the nucleus and are called orbitals.
  Each orbital contains a maximum of two electrons
• Orbitals differ in shape (s, p) and are grouped
  in shells 1, 2, 3
• P-orbitals are oriented along three axes

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Hybridization Structure/ Bonding in Methane
(CH4, an alkane)

• Carbon is bonded to four hydrogen atoms
• One s-orbital is combined with three p orbitals
• The resultant sp3 hybridized carbon is
  tetrahedral

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Bonding in Methane

• Each orbital is as far away as possible from the
  other orbitals
• Minimizes repulsion
• Angle 109.5o

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Bonding in Ethane

• Contains two
• sp3 hybridized
• carbon atoms
• - Each carbon
• atom is tetrahedral

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Structure/Bonding in Ethene ( H2CCH2, an alkene)
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Bonding in Ethene

• The sp2 hybridized carbon is trigonal

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What type of overlap is present in each bond of
CH3CHCH2?
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Bonding in Ethyne (an alkyne)

• The sp orbitals form two equivalent and linear
  sigma bonds

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Types of bonds in ethyne

• Sigma and pi bonds are formed

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Effect of hybridization on bond lengths

• 2s electrons are generally found closer to the
  nucleus than 2p electrons
• A hybrid orbital with a greater proportion of s
  character is of lower energy and is closer to the
  nucleus
• sp orbitals contain more s-character
• It forms shorter and stronger bonds

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Effect of hybridization on bond lengths
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C 10 J Course Outline

• At the end of this course you should be able to
• Describe the structure and bonding in alkanes,
  alkenes and alkynes in terms of the hybridization
  states of carbon.
• Represent alkanes, alkenes and alkynes as dash
  formulae, condensed formulae, and bond-line
  drawings.
• Name acyclic and cyclic alkanes, alkenes and
  alkynes using the IUPAC system of nomenclature.
• Represent constitutional isomers of hydrocarbons.
• Represent and name geometric isomers of alkenes
  using the cis/trans and E/Z systems.
• Carry out conformational analysis of simple
  alkanes with the aid of sawhorse and Newman
  projections.
• Devise syntheses of alkanes, alkenes and alkynes
  using the methods described in the syllabus.
• Explain the production and stability of alkyl
  radicals and carbocations.
• Provide detailed mechanisms for the halogenation
  of alkanes, alkenes and alkynes.
• Describe, with the aid of structural diagrams and
  curly arrows, the ionic mechanism and
  stereochemical outcome of the addition of
  electrophiles to alkenes and alkynes.
• Predict the products of the reaction of any given
  alkene and alkyne with the following oxidizing
  agents OsO4, KMnO4, O3.
• Explain the basis of the acidity of terminal
  alkynes and show their usefulness in synthesis.
• Define the terms chiral, enantiomer, racemic,
  optical activity.
• Make perspective drawings of the enantiomers and
  name them using the R-S system.