IUPAC nomenclature retains the common name aniline for \(\mathrm{C}_{\mathrm{e}} \mathrm{H}_{3} \mathrm{NH}_{2}\), the simplest arcanatic amine. Its simple derinatives are named using the prefixes \(o, w\), and \(p\), or numbers to locate substituents. Several derivatives of aniline have common names that are still widely used. Among these are tolusdine for a methyd-suhatitusted aniline and anisidine for a methoxyl-substituted aniline.

First, identify the parent compound and the substituents attached to the parent compound. In this case, aniline (C6H5NH2) is the parent compound, and we have two derivatives: one with a methyl substituent (toluidine) and one with a methoxy substituent (anisidine).

Next, name the substituent based on its atom or group, and use appropriate prefixes or numbers to indicate the position of the substituent. For example: - In toluidine (methyl-substituted aniline), the substituent is a methyl group. - In anisidine (methoxy-substituted aniline), the substituent is a methoxy group.

For derivatives of aniline, use the prefixes ortho (o-), meta (m-), and para (p-) or numbers (2-, 3-, 4-) to indicate the substituent location relative to the NH2 group (amino group) on the benzene ring. The position numbers start from the carbon atom connected to the NH2 group: - ortho (o-) or 2-: the substituent is located at the carbon atom adjacent to the amino group. - meta (m-) or 3-: the substituent is located at the carbon atom two positions away from the amino group. - para (p-) or 4-: the substituent is located at the carbon atom opposite to the amino group.

Combine the substituent name and its location (using prefixes or numbers) with the parent compound (aniline) to get the IUPAC name of the derivative. Here are some examples: 1. o-Toluidine (ortho-Toluidine) or 2-Toluidine: CH3 is at the ortho position (carbon 2) to the NH2 group on the benzene ring of aniline. IUPAC name: 2-Methylaniline 2. m-Toluidine (meta-Toluidine) or 3-Toluidine: CH3 is at the meta position (carbon 3) to the NH2 group on the benzene ring of aniline. IUPAC name: 3-Methylaniline 3. p-Toluidine (para-Toluidine) or 4-Toluidine: CH3 is at the para position (carbon 4) to the NH2 group on the benzene ring of aniline. IUPAC name: 4-Methylaniline 4. o-Anisidine (ortho-Anisidine) or 2-Anisidine: OCH3 is at the ortho position (carbon 2) to the NH2 group on the benzene ring of aniline. IUPAC name: 2-Methoxyaniline 5. m-Anisidine (meta-Anisidine) or 3-Anisidine: OCH3 is at the meta position (carbon 3) to the NH2 group on the benzene ring of aniline. IUPAC name: 3-Methoxyaniline 6. p-Anisidine (para-Anisidine) or 4-Anisidine: OCH3 is at the para position (carbon 4) to the NH2 group on the benzene ring of aniline. IUPAC name: 4-Methoxyaniline