MDCAT Organic Chemistry: Master Every Reaction in 3 Weeks

Organic chemistry accounts for 25–30 of the 68 Chemistry marks in MDCAT. Students who master it consistently rank higher.

The 7 Reaction Types You Must Know

1. Addition Reactions (Alkenes and Alkynes)

HX adds following Markovnikov's rule. Halogens add symmetrically. Know the bromine water test for unsaturation.

2. Substitution Reactions

Alkanes: free radical mechanism (initiation, propagation, termination). Benzene: electrophilic aromatic substitution (nitration, halogenation, Friedel-Crafts reactions). Know the catalyst for each.

3. Nucleophilic Substitution (SN1 and SN2)

SN2: one-step, back-side attack, favoured with primary alkyl halides and strong nucleophiles. SN1: two-step via carbocation, favoured with tertiary alkyl halides.

4. Elimination Reactions

Dehydrohalogenation (KOH/alcohol) and dehydration (H2SO4/heat) both form alkenes. Zaitsev's rule: the more substituted alkene is the major product.

5. Reactions of Carbonyl Compounds

Tollens' test (silver mirror) and Fehling's test distinguish aldehydes from ketones. Iodoform test identifies methyl ketones. Aldehydes are oxidised easily; ketones are not.

6. Carboxylic Acids and Derivatives

Esterification (H2SO4 catalyst, reversible), saponification (ester hydrolysis in base, irreversible — soap making). Reactivities: acid chlorides > anhydrides > esters > amides.

7. Amines

Basic properties from lone pair on nitrogen. Reaction with acids to form salts, with acid chlorides to form amides. Primary amines react with HNO2 to form diazonium salts.

The 3-Week Study System

• Week 1 — Mechanisms: One reaction type per day. Derive products from mechanism using electron-pushing arrows.
• Week 2 — Functional Groups: One A4 sheet per functional group listing all reactions, reagents, and conditions.
• Week 3 — MCQ Drilling: Past-paper organic chemistry MCQs exclusively. Flag every named test and named rule.