IIT-JEE MAINS 2027 cheat sheet for Organic Chemistry! 📱 Practice 1 Lakh+ PYQs on ExamBhai.com! - Free Study Material

Organic Chemistry Key Concepts & Formulae: IIT-JEE Mains 2027

Mastering Organic Chemistry for IIT-JEE Mains requires a structured understanding of fundamental principles, reaction mechanisms, and functional group transformations. Below is a concise chapter-wise summary designed to serve as a high-yield revision reference.

1. General Organic Chemistry (GOC) & Isomerism

• Electronic Effects: Inductive ($I$), Resonance/Mesomeric ($M$), Hyperconjugation ($H$), and Electromeric ($E$) effects govern stability.
• Carbocation Stability: Cyclopropenyl cation $>$ Benzyl $>$ Allyl $>$ $3^\circ$ $>$ $2^\circ$ $>$ $1^\circ$ $>$ Methyl.
• Carbanion Stability: $\text{sp} > \text{sp}^2 > \text{sp}^3$; Stabilized by electron-withdrawing groups ($-I, -M$).
• Acidity Order: $\text{RCOOH} > \text{ArOH} > \text{H}_2\text{O} > \text{ROH} > \text{HC}\equiv\text{CH} > \text{NH}_3$.

2. Hydrocarbons

• Electrophilic Addition to Alkenes: Follows Markovnikov's rule (via carbocation intermediate). Anti-Markovnikov addition occurs in the presence of peroxides ($\text{HBr} + \text{R}_2\text{O}_2$).
• Ozonolysis: Reductive ($\text{O}_3/\text{Zn, H}_2\text{O}$) yields aldehydes/ketones; Oxidative ($\text{O}_3/\text{H}_2\text{O}_2$) yields carboxylic acids.
• Aromaticity: Cyclic, planar, fully conjugated systems with $(4n + 2)\pi$ electrons (Hückel's Rule).

3. Reaction Mechanisms ($\text{S}_\text{N}1$, $\text{S}_\text{N}2$, $\text{E}1$, $\text{E}2$)

• $\text{S}_\text{N}1$: Two-step, carbocation intermediate, racemization, favored by polar protic solvents and $3^\circ$ alkyl halides.
• $\text{S}_\text{N}2$: One-step, transition state, inversion of configuration (Walden Inversion), favored by polar aprotic solvents and $1^\circ$ alkyl halides.

4. Representative Structure: Aspirin

Consider the structure of Acetylsalicylic acid (Aspirin) given below, commonly prepared via the acetylation of salicylic acid:

```smiles\nCC(=O)Oc1ccccc1C(=O)O\n```