Write down IUPAC name of the following organic compounds. i) (CH3)2 C = CH CHO ii) COOH COOH

i) The IUPAC name of the compound $(\mathrm{CH}{}_3){}_2\mathrm{C}=\mathrm{CH}-\mathrm{CHO}$ is 3-methylbut-2-enal.

Explanation:

• The parent chain is the longest continuous carbon chain containing the functional groups, which is 4 carbons (but-).
• The compound contains a double bond between C-2 and C-3, so it is named as but-2-ene.
• The aldehyde group (–CHO) is at the end (C-1), so the suffix is -al.
• A methyl group (–CH₃) is attached to C-3, so the prefix is 3-methyl.

3-Methylbut-2-enal3-Methylbut-2-enal

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ii) The IUPAC name of the compound $\mathrm{COOH}$ (attached to a central carbon with another $\mathrm{COOH}$) is ethanedioic acid.

Ethanedioic acid (Oxalic acid)Ethanedioic acid (Oxalic acid)

Explanation:

• The structure is HOOC–COOH, meaning two carboxylic acid (–COOH) groups attached to a 2-carbon chain.
• The parent chain is ethane (2 carbons) with two –COOH groups, so the suffix is -dioic acid.
• The name is derived from ethane + dioic acid.