CBSE Class 12 Organic Chemistry – Important Conversions from Past 10 Years (2025-2026)

Based on analysis of 2015–2024 CBSE papers. Perfect for 2026 Boards prep!

Key Trends in Organic Conversions (2015–2024 Analysis)

Weightage: 5–10 marks (2–3 conversions in 2/3/5 mark questions).
Repeated Themes: Alcohols to aldehydes/ketones, haloalkanes to amines, carboxylic acids to amines, benzene derivatives, functional group interconversions.
Difficulty: Medium; focus on reagents, conditions, mechanisms (SN1/SN2, oxidation/reduction).
Changes: More multi-step conversions in 2022–2024, emphasis on named reactions (Hofmann, Cannizzaro, Haloform).

Conversion	Reagents/Conditions	Years Repeated	Notes
Ethanol to Ethene	Conc. H₂SO₄, 443K (dehydration)	2015, 2017, 2019, 2022, 2024	Repeated 5x; Zaitsev's rule for major product.
Benzene to Nitrobenzene	Conc. HNO₃ + Conc. H₂SO₄ (nitration)	2016, 2018, 2020, 2023, 2024	Repeated 5x; Electrophilic aromatic substitution.
Nitrobenzene to Aniline	Sn/HCl or Fe/HCl (reduction)	2015, 2018, 2021, 2023	Repeated 4x; Use catalytic hydrogenation alternative.
Acetaldehyde to Acetic acid	KMnO₄ or K₂Cr₂O₇/H⁺ (oxidation)	2017, 2019, 2022, 2024	Repeated 4x; Mild oxidant for aldehydes.
Propanone to 2-Methylpropan-2-ol	CH₃MgBr, then H₃O⁺ (Grignard)	2016, 2019, 2021, 2023	Repeated 4x; Tertiary alcohol formation.
Benzoic acid to Benzamide	NH₃, heat (amidation)	2018, 2020, 2022	Repeated 3x; Dehydration of ammonium salt.
Phenol to Salicylic acid	CO₂, NaOH, then H⁺ (Kolbe-Schmitt)	2017, 2020, 2023	Repeated 3x; Named reaction.
Chlorobenzene to Phenol	NaOH, 623K, high pressure (Dow's)	2015, 2019, 2022	Repeated 3x; Nucleophilic substitution.
Aniline to Diazonium salt	NaNO₂/HCl, 0–5°C (diazotization)	2016, 2021, 2024	Repeated 3x; Sandmeyer precursor.
Ethanol to Acetone	Propanal + CrO₃ (oxidation via acetaldehyde)	2018, 2021, 2023	Repeated 3x; Multi-step.

Explain the mechanism of SN1 and SN2 reactions with examples from haloalkanes. (2024, 5 marks)
Convert benzene to acetophenone and explain the reaction. (2023, 3 marks)
Give the Iodoform test for acetaldehyde and acetone. (2022, 2 marks)
Convert nitrobenzene to aniline and then to phenol. (2021, 5 marks)
Explain Cannizzaro reaction with example. (2023, 3 marks)
Convert ethanol to ethene and then to chloroethane. (2024, 3 marks)
Distinguish between 1°, 2°, 3° amines using Hinsberg's test. (2022, 2 marks)
Convert benzoic acid to benzaldehyde. (2021, 2 marks)