Functional Groups – Study Notes
Program: Military Nursing Service (B.Sc.)
Subject: Chemistry
Topic: Functional Groups
1. Simple Explanation
A functional group is a specific arrangement of atoms that imparts a characteristic chemical reactivity to a molecule.
- Think of it as a “reactivity tag” that tells you how a compound will behave in a chemical reaction.
- Functional groups determine the type of chemical bond(s) that can be formed or broken, the polarity of the molecule, and its solubility or acid/base properties.
Why it matters for nursing
Many drugs, disinfectants, and antiseptics contain functional groups that dictate how they interact with body tissues, enzymes, and microorganisms.
2. Key Points
| Category | General Formula | Common Examples | Typical Reactions |
|---|---|---|---|
| Alkanes | CₙH₂ₙ₊₂ | Methane, Ethane | Combustion, free‑radical halogenation |
| Alkenes | CₙH₂ₙ | Ethene, Propene | Electrophilic addition (H₂, Br₂, H₂O, HX) |
| Alkynes | CₙH₂ₙ₋₂ | Ethyne, Propyne | Electrophilic addition (H₂, H₂O, HX, CO₂) |
| Alcohols | R–OH | Ethanol, Isopropanol | Oxidation → aldehydes/ketones, esterification |
| Aldehydes | R–CHO | Formaldehyde, Acetaldehyde | Nucleophilic addition, reduction |
| Ketones | R–CO–R′ | Acetone, Cyclohexanone | Nucleophilic addition, reduction |
| Carboxylic Acids | R–COOH | Acetic acid, Benzoic acid | Deprotonation → carboxylates, esterification |
| Esters | R–COO–R′ | Ethyl acetate, Methyl salicylate | Hydrolysis (acidic or basic) |
| Amides | R–CONH₂ | Acetamide, Urea | Hydrolysis, amidation |
| Amines | R–NH₂, R₂NH, R₃N | Methylamine, aniline, triethylamine | Protonation, alkylation |
| Ethers | R–O–R′ | Diethyl ether, Methoxymethane | Acid‑catalyzed cleavage |
| Halides | R–X (X = F, Cl, Br, I) | Chloromethane, Bromobenzene | Nucleophilic substitution, elimination |
| Nitro Compounds | R–NO₂ | Nitrobenzene | Reduction to amines |
| Phenols | Ar–OH | Phenol, Hydroquinone | Acid–base behavior, electrophilic substitution |
Functional Group Hierarchy (IUPAC Priority)
- Carboxylic acids
- Esters
- Amides
- Nitriles
- Aldehydes
- Ketones
- Alcohols
- Ethers
- Amines
- Alkenes/alkynes
- Others (halides, nitro, etc.)
Tip: The highest‑priority group becomes the suffix of the IUPAC name.
Common Properties
| Property | Influenced by |
|---|---|
| Polarity | Presence of electroneg |