4.1

• Systematic nomenclature can be used to name organic compounds
• Alkanes provide the basis of the naming system
• The stem of each name indicates how many carbon atoms are in the longest chain in one molecule of the compound
• If there are any side-chains or functional groups present, the position of these groups is indicated by numbering the carbon atoms in the longest chain
• The hydrocarbon side-chain is shown in brackets in the structural formula
• The side-chain is named by adding ‘-yl’ to the normal alkane stem
• Naming conventions for side chains:
• If there are multiple of the same alkyl side-chain or functional groups, di- (for two), tri- (for three), or tetra- (for four) is added in front of its name
• Adjacent numbers have a comma between them
• Numbers are separated from words by a hyphen
• If there is more than one type of alkyl side-chain, they are listed in alphabetic order
• An aliphatic compound is straight or branched-chain and includes cyclic organic compounds that do not contain a benzene ring
• Homologous series in organic chemistry:
• A group of organic compounds that have the same functional group
• Each successive member differs by CH2
• Functional groups determine the physical and chemical properties of molecules
• Organic compounds can be classified as aliphatic, alicyclic, or aromatic
• Organic compounds can also be described as saturated or unsaturated
• Saturated compounds contain single carbon-carbon bonds only
• Unsaturated compounds contain at least one carbon-carbon bond that is not single, e.g. C=C or C≡C
• Homologous series: group of organic compounds with the same functional group, differing by CH
• Alkanes general formula: CnH2n+2
• Alkenes general formula: CnH2n
• General formulae can predict the chemical formula of any member of the same homologous series
• Eicosane: alkane with 20 carbons, formula C20H42
• 1. nonapentacontane: alkane with 59 carbons, formula C59H120
• Oct-3-ene: alkene with 8 carbons, formula C8H16
• Structural isomerism: compounds with the same molecular formula but different structural formulae
• Chain isomerism: caused by branching, e.g., pentane and 2,2-dimethylpropane
• Positional isomerism: functional group in different positions, e.g., butan-1-ol and butan-2-ol
• Functional group isomerism: different functional groups, e.g., butanol and ethoxyethane
• Dibromopropane isomers: positional isomerism with two bromine atoms bonded to different carbon atoms
• Curly arrows in reaction mechanisms show movement of electrons
• Single-headed arrows: movement of one electron in homolytic fission or termination of radicals
• Double-headed arrows: movement of a pair of electrons in fission to form positive and negative ions or when lone pair attacks a positive center
• Curly arrows in addition reactions, substitution reactions, and elimination reactions
• Alkanes are a homologous series made up of saturated hydrocarbons (containing only hydrogen and carbon) joined by sigma (σ) bonds
• Alkanes are nonpolar molecules with no partial positive or negative charges
• Alkanes do not react with polar reagents
• Each carbon in alkanes forms four covalent bonds, resulting in a tetrahedral bonding arrangement with a bond angle of 109.5