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!