1. Carbonyl Group Basics

• sp2 C, planar, electrophilic (C^delta+)
• Reactivity: HCHO > other aldehydes > ketones (steric + electronic)
• Mechanism: Nu- → C^delta+ → tetrahedral alkoxide → protonation → product

2. NH3 Derivatives (Condensation — loss of H2O)

3. Distinction Tests

4. Reductions

5. Aldol vs Cannizzaro (Most Important Rule)

$\boxed{\text{Alpha-H present} \Rightarrow \text{ALDOL} \quad | \quad \text{No alpha-H} \Rightarrow \text{CANNIZZARO}}$

• Aldol: dil. NaOH → beta-hydroxy carbonyl → (heat) → alpha,beta-unsaturated
• Cannizzaro: conc. NaOH → RCOOH + RCH2OH (disproportionation)
• No alpha-H examples: HCHO, C6H5CHO, (CH3)3CCHO

6. Iodoform Test — Positive List

Positive: CH3CHO, CH3COCH3, CH3COR (any), CH3CH2OH, (CH3)2CHOH, C6H5COCH3 Negative: HCHO, CH3OH, C6H5CHO, CH3CH2COCH2CH3, CH3CH2CH2OH

7. Grignard Products

• HCHO + RMgX → Primary alcohol (R-CH2OH)
• RCHO + R'MgX → Secondary alcohol
• R2CO + R'MgX → Tertiary alcohol

8. Key SMILES

• Formaldehyde: C=O
• Acetaldehyde: CC=O
• Benzaldehyde: O=Cc1ccccc1
• Iodoform: IC(I)I
• Crotonaldehyde: C/C=C/C=O
• Cinnamaldehyde: O=C/C=C/c1ccccc1

9. Named Reactions Summary

• Aldol: dil. NaOH + alpha-H → beta-hydroxy carbonyl
• Cannizzaro: conc. NaOH + no alpha-H → acid salt + alcohol
• Haloform: I2/NaOH + CH3CO- → CHI3 + RCOONa
• Clemmensen: Zn-Hg/HCl → C=O to CH2 (acidic)
• Wolff-Kishner: NH2NH2/KOH → C=O to CH2 (basic)

10. Exam Traps Checklist

• Ketones do NOT give Tollens' / Fehling's
• 2,4-DNP does NOT distinguish aldehyde from ketone
• NaBH4 gives alcohol (NOT CH2)
• Benzaldehyde → Cannizzaro (NO alpha-H)
• Methanol → NEGATIVE iodoform
• Diethyl ketone → NEGATIVE iodoform (no CH3CO-)
• Ethanol → POSITIVE iodoform (oxidized to CH3CHO)
• Isopropanol → POSITIVE iodoform (oxidized to acetone)