S3.2.5 Naming

Carbon Chain Prefixes

Naming Alkanes

Alkane names use prefixes based on carbon chain length.

Suffix is -ane.

Naming Cyclic Alkanes

Cyclic alkanes have ring structures with formula C_nH_2n.

Prefix is Cyclo-

Branched-Chain Alkanes

Have branches which are alkyl substituents like –CH₃ or –C₂H₅.

Naming Branched Alkanes

Identify the longest continuous carbon chain.

Number the carbon chain to give the branches the lowest numbers.

If multiple identical alkyl groups exist, use di-, tri-, etc.

Alkene Reactivity

C=C bond has high electron density attracting electrophiles.

π bond is weaker than σ bond, allowing electrophilic addition.

Naming Alkenes Process

Identify the longest chain with the C=C bond and assign the lowest number to the bond.

Add the suffix -ene.

Use numbers to indicate the position of the double bond.

Structural Isomers of Alkenes

Alkenes with same molecular formula but different C=C positions are isomers.

Position numbering affects naming (e.g., -1-ene vs -2-ene).

Invalid Alkene Positions

Double bond is always given the lowest position number. Some names like -3-ene are renamed for correctness.

Naming Alkynes

Find the longest carbon chain containing the triple bond and number it for lowest position.

Add the suffix -yne to the root name

Indicate triple bond position with a number.

Naming Alcohols

Identify the longest carbon chain with hydroxyl group and assign the lowest number to it.

Change the -e of the parent alkane to -ol.

Use a number to indicate OH position if needed.

Naming Carboxylic Acids

Identify the longest carbon chain including the COOH group, which is always carbon-1.

Replace the -e of the parent alkane with -oic acid.

Number branches from the COOH carbon.

Naming Aldehydes

Aldehydes have the -CHO functional group.

Name them by replacing the -e of the parent alkane with -al.

The carbon in the -CHO group is always carbon 1.

Naming Ketones

Ketones have the C=O group bonded to two carbon atoms.

Name them by replacing the -e of the parent alkane with -one.

Number the chain to give the C=O the lowest possible number.

Naming Primary Amines

Identify longest carbon chain with -NH2 group

Number it to give lowest possible position to -NH2

Name as 'alkane number-amine' (e.g., propane-1-amine).

Naming Secondary Amines

Use uppercase 'N' to indicate alkyl group(s) attached to nitrogen

Name as 'N-alkyl parentamine' (e.g., N-methylpropylamine).

Naming Tertiary Amines

Use uppercase 'N,N' for two alkyl groups on nitrogen

Name as 'N,N-dialkyl parentamine' (e.g., N,N-dimethylbutanamine).

Naming Primary Amides

Replace '-oic acid' of carboxylic acid name with '-amide'.

Carbon chain length gives the prefix (e.g. ethane → ethanamide).

No alkyl group on nitrogen.

Naming Secondary Amides

Use 'N-' to denote alkyl groups attached to nitrogen.

Base name is from the amide chain

Prefix the N-alkyl group (e.g. N-methylpropanamide).

Naming Tertiary Amides

Use 'N,N-' to denote two alkyl groups on nitrogen.

Alphabetize substituents and attach them to the amide name (e.g. N-ethyl-N-methylpropanamide).

Naming Ethers

Ethers have 2 alkyl groups bonded to O.

Shorter group (with O) becomes alkoxy substituent.

Longer group becomes alkane stem.

Monohalogenoalkane naming rule

Identify longest carbon chain with halogen.

Use halogen prefix + alkane name.

Number chain to give halogen lowest possible number.

Multiple same halogen atoms

Use prefixes di-, tri-, tetra- with position numbers.

Number chain for lowest set of locants.

Different halogens in one molecule

List halogens alphabetically with positions.

Number chain for lowest total position numbers.

Branched halogenoalkanes

Name alkyl branches and halogens in alphabetical order.

Use position numbers and longest chain as base.

Lowest numbers take priority.