Example 1 — Aldehyde

Structure: CH₃CH₂CH₂CHO (four-carbon chain, terminal aldehyde)

1. Principal functional group: aldehyde → suffix -al
2. Parent chain: 4 carbons → but-
3. Aldehyde carbon is C-1; no other substituents
4. Name: butanal

Example 2 — Alcohol with substituent

Structure: CH₃CH(OH)CH₂CH₃ (four-carbon chain, hydroxyl on C-2)

1. Principal functional group: alcohol → suffix -ol
2. Parent chain: 4 carbons → but-
3. Number from the end closest to the OH: hydroxyl at C-2
4. No other substituents
5. Name: butan-2-ol

Example 3 — Ketone

Structure: CH₃COCH₂CH₂CH₃ (five-carbon chain, carbonyl at C-2)

1. Principal functional group: ketone → suffix -one
2. Parent chain: 5 carbons → pent-
3. Number from the end closest to the carbonyl: C-2
4. Name: pentan-2-one

Example 4 — Alkene with substituent

Structure: CH₃CH=C(CH₃)CH₂CH₃ (five-carbon chain with a double bond and a methyl branch)

1. Principal functional group: alkene → suffix -ene
2. Parent chain: 5 carbons → pent-
3. Double bond at C-2 (lower locant from left end)
4. Methyl substituent at C-3
5. Name: 3-methylpent-2-ene

Example 5 — Carboxylic acid

Structure: CH₃CH₂COOH (three-carbon chain, carboxylic acid)

1. Principal functional group: carboxylic acid → suffix -oic acid
2. Parent chain: 3 carbons → prop-
3. Carboxyl carbon is C-1; no locant needed
4. Name: propanoic acid

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