Organic Chemistry
Jan 13, 2016
Organic Chemistry
What is organic chemistry?
• All biological molecules – simple sugars to complex nucleic acids
• All fossil fuels – including oil, coal, and natural gas
• Most synthetic materials – nylon, Lycra, Gore-Tex
• Consumer products – paints, detergents, refrigerants
Define Organic Compound
• It is a compound that contains carbon and, in nearly all cases, also hydrogen in a covalently bonded structure
Why Carbon?
• Catenation, which is the ability for carbon to form bonds with other carbon atoms to form carbon chains and rings
• Carbon is able to form four strong covalent bonds with other carbon atoms
Classification
• The classification system is based on the structure and bonding species
• Functional groups, part of bonding species, are identifiers of the nature(chemical reaction) of the organic compound
Types of Reactants
• Saturated• Unsaturated• Aliphatic• Arenes• Electrophile• Nucleophile
Saturated
• Compound that only contain single bonds– Ex: alkanes
Unsaturated
• Compounds which contain double or triple bonds– Ex: alkene, arenes
Aliphatics
• Compounds which do not contain a benzene ring– Alkanes, alkenes
Arenes
• Compounds which contain a benzene ring; all are unsaturated– Benzene, phenol
Electrophile (electron seeking)
• An electron-deficient species which therefore attracted to parts of molecules which are electron rich
• Electrophiles are positive ions or have partial positive charge
• Ex: NO2+, H+, Brδ+
Nucleophile (nucleus seeking)
• An electron rich species which is therefore attracted to parts of a molecules which are electron deficient
• Nucleophiles have a lone pair of electrons and may also have a negative charge – Ex: Cl-, OH-, NH3
Types of Reactions
• Addition• Substitution• Elimination• Addition-elimination
Addition
• Occurs when two reactants combine to form a single product
• Characteristic of unsaturated compounds– Ex: C2H4 + Br2 C2H4Br2
Substitution
• Occurs when one atom or group of atoms in a compound is replaced by a different atom or group
• Characteristic of saturated compounds and aromatic compounds– Ex: CH4 + Cl2 CH3Cl + HCl
Elimination
• Occurs when a small molecule is lost from a larger compound
• Usually results in the formation of a double or triple bond
• When the molecule eliminated is H2O the reaction is dehydration– C2H5OH C2H4 + H2O
Addition-elimination
• Occurs when two reactants join together (addition) and in the process a small molecule is lost (elimination)
• Reaction occurs between a functional group in each reactant
• This reaction may also be called condensation– RNH2 + R’COOH R’CONHR + H2O
Types of bond breaking (bond fission)
• Homolytic fission• Heterolytic fission
Homolytic fission
• When a covalent bond breaks by splitting the shared pair of electrons between the two products
• Produces two free radicals each with an unpaired electron
Heterolytic fission
• When covalent bond breaks with both the shared electrons going to one of the products
• Produces two oppositely charged ions
Review
• HL Book pages 361-365
Barware of the Curly Arrow!