2. NOMENCLATURE OF ORGANIC COMPOUNDS

Introduction

Nomenclature means giving proper IUPAC names to organic compounds. The IUPAC system helps every student, teacher, and scientist understand the same structure with the same name worldwide. These rules are simple once you understand how to find the parent chain, functional group, and substituents.

General Steps in IUPAC Naming

  1. Identify the longest carbon chain → this becomes the parent name.
  2. Identify the functional group → this gives the suffix.
  3. Identify substituents (side groups) → this gives prefixes.
  4. Number the chain to give the lowest number to the functional group.
  5. Write the name as: prefix + parent chain + suffix.

Nomenclature of Alkanes

Alkanes are saturated hydrocarbons (single bonds only). Parent chain names: methane, ethane, propane, butane, pentane, hexane etc.

General formula: CnH2n+2

Example: CH3–CH2–CH3 → Propane

Nomenclature of Alkenes

Alkenes contain at least one double bond. Name ends with -ene.

Rule: Number the chain so the double bond gets the lowest possible number.

Example: CH2=CH–CH3 → Prop-1-ene

Nomenclature of Dienes

Dienes contain two double bonds. Name ends with -diene.

Example: CH2=CH–CH=CH2 → Buta-1,3-diene

Nomenclature of Alkynes

Alkynes contain a triple bond. Name ends with -yne.

Example: CH≡CH → Ethyne

Nomenclature of Alcohols

Alcohols contain the –OH group and end with -ol.

Rule: Number the chain so that the –OH group gets the lowest number.

Example: CH3–CH2–OH → Ethanol

Nomenclature of Aldehydes

Aldehydes contain the –CHO group. Name ends with -al.

Example: H–CHO → Methanal (Formaldehyde)

Nomenclature of Ketones

Ketones contain the carbonyl group (>C=O) in the middle of the chain. Name ends with -one.

Example: CH3–CO–CH3 → Propanone

Nomenclature of Amides

Amides contain the –CONH2 group. Name ends with -amide.

Example: CH–CONH → Ethanamide

Nomenclature of Amines

Amines contain the –NH2 functional group. Name ends with -amine.

Example: CH3–NH2 → Methanamine

Nomenclature of Phenols

Phenols have an –OH group attached directly to a benzene ring. Name ends with phenol.

Example: C6H5–OH → Phenol

Nomenclature of Alkyl Halides

Alkyl halides contain halogen atoms (Cl, Br, I, F). Halogen names are written as prefixes: fluoro, chloro, bromo, iodo.

Example: CH3–Cl → Chloromethane

Nomenclature of Carboxylic Acids

Carboxylic acids contain –COOH and end with -oic acid.

Example: H–COOH → Methanoic acid

Nomenclature of Esters

Esters are written as: Alkyl group + parent acid + -oate

Example: CH3–COO–CH3 → Methyl ethanoate

Nomenclature of Acid Chlorides

Acid chlorides contain the –COCl group. Name ends with -oyl chloride.

Example: CH3–COCl → Ethanoyl chloride

Nomenclature of Cycloalkanes

Cycloalkanes are ring compounds. Name begins with cyclo-.

Example: C6H12 (ring) → Cyclohexane

Detailed Notes:

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BASICS:

PATH: PHARMD/PHARMD NOTES/ PHARMD FIRST YEAR NOTES/ ORGANIC CHEMISTRY/ PHARMACEUTICAL ORGANIC CHEMISTRY/NOMENCLATURE OF ORGANIC COMPOUND BELONGING TO THE FOLLOWING CLASSES ALKANES, ALKENES, DIENES, ALKYNES, ALCOHOLS, ALDEHYDES, KETONES, AMIDES, AMINES, PHENOLS, ALKYL HALIDES, CARBOXYLIC ACID, ESTERS, ACID CHLORIDES AND CYCLOALKANES.

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