Lecture 3

General Organic Chemistry (3)

1. Classification of Organic Compounds

2. Nomenclature of Hydrocarbons

3. Nomenclature of the Derivatives of Hydrocarbons

4. Nomenclature of the Derivatives of Aromatic Hydrocarbons

1 Classification of Organic Compounds

Classification by carbon skeletons

Classification by Functional Groups

The compounds in a particular family are characterized by the presence of a certain arrangement of atoms called a functional group

A functional group is defined as an atom or a group of atoms that effectively determines the chemical properties of an organic compound.

have similar chemical properties because they contain the same functional group –OH. They are classified into the same homologous series — Alcohols.

Family	General formula	Functional group	Specific example
			Formula	IUPAC name
Alkane	RH	C – H and C –C bonds	CH3CH3	Ethane
Alkene	RCH = CH2 RCH = CHR R2C = CHR R2C = CR2		CH2 = CH2	Ethene
Alkyne	RC ≡ CH RC ≡ CR	– C ≡ C –	HC≡CH	Ethyne
Aromatic hydrocarbon	ArH	Aromatic ring		Benzene
Haloalkane	RX		CH3Cl	Chloromethane
Alcohol	ROH		CH3OH	Methanol

Family	General formula	Functional group	Specific example
			Formula	IUPAC name
Ether	R – O – R		CH3 – O – CH3	Methoxymethane
Aldehyde				Methanal
Ketone				Propanone
Carboxylic acid				Ethanoic acid
Amine	RNH2 R2NH R3N		CH3NH2	Methylamine
Nitrile	RC ≡ N	– C ≡ N	CH3CN	Ethanenitrile
Ester				Methyl ethanoate
Acyl halide				Ethanoyl chloride
Amide				Ethanamide
Acid anhydride				Ethanoic anhydride

Members in the same series can be represented by a general formula.

e.g. General formula of alkanes: C_nH_2n+2

General formula of alcohols: C_nH_2n+1OH

A homologous series is a series of compounds that have the same functional group, and each member differs from the next member by a – CH₂ – unit in their formulae. Members of a homologous series have similar chemical properties

The physical properties change gradually along the homologous series e.g. the longer the carbon chain in molecule ( or the greater the molecular mass)

- the greater the attractive force between molecules

- the higher the melting point and boiling point