Synthesis practice is a cornerstone of advanced organic chemistry learning, especially crucial for Class 12 students aiming to excel in examinations and develop a robust conceptual foundation. This “Synthesis Practice for Class 12 Worksheet” provides a structured set of problems that guide learners through fundamental transformations, multi-step linear syntheses, and retrosynthetic analysis. By methodically working through these challenges, students hone their ability to design reaction pathways, select appropriate reagents, and predict outcomes with confidence—skills that will serve them well in academic assessments and beyond.

Table of Contents

1) Fundamental Transformation Problems (20 Examples)

These are primarily single-step or very short transformation challenges, focusing on choosing correct reagents and predicting products.

1. Oxidation of Alcohols to Aldehydes/Ketones

Convert 1-propanol to propanal
Convert cyclohexanol to cyclohexanone
Convert 2-butanol to 2-butanone
Convert isobutyl alcohol (2-methyl-1-propanol) to isobutyraldehyde
Convert benzyl alcohol to benzaldehyde
Convert 2-methylcyclohexanol to 2-methylcyclohexanone

2. Alkene Functionalizations

Convert oct-1-ene to octan-1-ol
Convert 2-butene to 2-butanol
Convert 1-methylcyclohexene to 2-methylcyclohexanol
Convert trans-2-butene to meso-2,3-butanediol
Convert styrene to styrene oxide
Convert cyclohexene to trans-1,2-cyclohexanediol

3. Reduction Reactions

Convert acetophenone to 1-phenylethanol
Convert ethyl benzoate (an ester) to benzyl alcohol
Convert benzonitrile to benzylamine
Convert cyclohexanone to cyclohexanol
Convert butanal to 1-butanol
Convert nitrobenzene to aniline
Convert phenylacetylene to styrene
Convert 4-nitrotoluene to 4-aminotoluene (p-toluidine)

2) Multi-Step Linear Synthesis Challenges (20 Examples)

These problems typically involve 3–5 steps from simple starting materials to moderately complex targets.

Synthesize 4-chloro-2-pentanone from 1-propanol
Convert cyclohexanol to cyclohexanecarboxylic acid
Transform 1-pentanol to 2-hexanone
Convert 1-butanol to 2-butanone
Solution Outline:
Synthesize 4-methoxyacetophenone from toluene
Transform benzene to 3-phenylpropanoic acid
Synthesize p-bromoaniline from benzene
Convert 1-propanol to 1-butanol
Synthesize 4-bromobenzoic acid from toluene
Prepare 2-methyl-2-phenylpropanol from benzene
Convert 1-hexene to 2-hexanol
Synthesize cyclohexylamine from cyclohexanol
Convert ethanol to 2-butanol
Synthesize 2-butanone from acetylene
Prepare m-xylene from benzene
Transform benzyl chloride to phenylacetic acid
Convert 1-butanol to 2-butanol
Synthesize 2-pentanone from ethyl acetoacetate (typical β-keto ester approach)
Convert chlorobenzene to phenol
Convert 3-buten-1-ol to 2-butenal (crotonaldehyde)

3) Retrosynthetic Analysis Problems (20 Examples)

Here you start from the product and work backward, then outline a forward synthesis.

Design a synthesis for 2-methyl-3-pentanone
Synthesize 3-phenyl-2-butanone
Prepare 4-hydroxy-4-methyl-2-pentanone
Synthesize 5-methyl-3-heptanol
Design a synthesis for 2,4-dimethyl-3-pentanol
Prepare 2-methylcyclopentanone
Synthesize 3-ethylcyclohexanol
Design a synthesis for 4-tert-butylcyclohexanone
Retrosynthesis for 2-phenylethanol
Synthesize 3-methyl-2-cyclohexenone
Design a synthesis of 1-phenyl-1-propanol
Retrosynthesis of 2-methyl-2-butanol
Synthesize 4-phenyl-2-butanone
Prepare 2,5-hexanedione
Synthesize 2-benzyl-1,3-propanediol
Design a synthesis of 4-ethyl-3-hexanone
Synthesize phenylacetic acid
Prepare 1,3-diphenyl-1-propanone
Synthesize cyclopentylamine
Design a synthesis for 2,3-dimethyl-2-butanol

4) Stereochemical Control Problems (20 Examples)

These tasks emphasize stereoselectivity, enantioselectivity, or diastereoselectivity in synthesis.

Synthesize (R)-2-octanol with >95% ee
Prepare (S)-1-phenylethanol from acetophenone
Design a synthesis of (2R,3R)-2,3-butanediol
Synthesize (S)-3-hydroxybutanoic acid
Prepare (R)-1,2-propanediol
Synthesize cis-4-tert-butylcyclohexanol
Prepare trans-2-methylcyclohexanol
Design a synthesis of (1R,2R)-1,2-diphenylethane-1,2-diol
Synthesize (S)-1-phenylethylamine
Prepare (R)-2-chlorobutane
Synthesize (S,S)-2,3-butanediol from (Z)-2-butene
Prepare (R)-2-butanol via microbial fermentation
Design a synthesis of (R)-mandelic acid
Synthesize (R)-3-methyl-3-phenylpropan-1-ol
Prepare (2S,3S)-2,3-butanediol from an alkyne
Synthesize (R)-2-hydroxy-4-phenylbutanoic acid
Prepare (R)-2-amino-3-phenylpropanoic acid (L-phenylalanine)
Design a route to (E)-3-hexen-1-ol with high stereochemical purity
Prepare (S)-glycidol
Synthesize (S)-(+)-carvone from (R)-limonene (illustrative natural product interconversion)

5) Named Reaction Applications (20 Examples)

Focus on famous name reactions (Wittig, Grignard, Aldol, Diels–Alder, Friedel–Crafts, etc.) in synthetic routes.

Use the Wittig reaction to prepare (E)-4-phenyl-3-buten-2-one
Apply the Grignard reaction to synthesize 2-methyl-2-phenylpropan-1-ol
Employ the aldol reaction to prepare 4-hydroxy-4-methyl-2-pentanone
Perform a Claisen condensation to synthesize diethyl malonate derivative
Use the Michael addition to form 3-oxo-5-phenylpentanoate
Apply the Diels–Alder reaction to prepare a substituted cyclohexene
Use Robinson annulation to construct a bicyclic enone
Synthesize 1,2,3,4-tetrahydronaphthalene using Friedel–Crafts
Perform a Beckmann rearrangement to prepare caprolactam
Use the Cannizzaro reaction to make benzyl alcohol + benzoic acid
Perform a Sandmeyer reaction to convert aniline to chlorobenzene
Employ the Birch reduction to synthesize 1,4-cyclohexadiene from benzene
Use the Wolff–Kishner reduction to convert cyclohexanone to cyclohexane
Apply the Clemmensen reduction to convert benzaldehyde to toluene
Carry out the Rosenmund reduction to convert benzoyl chloride to benzaldehyde
Perform the Pinacol rearrangement on pinacol to pinacolone
Use the Prins reaction to form a 1,3-dioxane
Synthesize a β-lactam ring via the Staudinger reaction
Use the Mannich reaction to prepare β-amino ketones
Use the Baeyer–Villiger oxidation to transform cyclohexanone into ε-caprolactone

6) Advanced Multi-Step Synthesis Challenges (20 Examples)

These problems require longer or convergent routes and integration of multiple reaction types.

Convergent synthesis of 1,5-diphenylpentan-3-one
Synthesize menthol from citronellal
Prepare 2-phenylchroman-4-one (a flavanone)
Design a synthesis of ethyl 2-acetamido-3-phenylpropanoate (protected phenylalanine ester)
Convergent route to 3,7-dimethyl-6-octen-1-ol (citronellol)
Synthesize 4-benzyl-2,6-dimethylheptan-4-ol
Prepare the tetracyclic core of steroids (high-level challenge)
Synthesize p-methoxycinnamic acid from benzaldehyde
Prepare 3,4-dihydropyran ring via Prins cyclization
Convergent synthesis of 2-benzyl-1,3-propanediol
Synthesize lysergic acid skeleton (very advanced)
Preparation of tropinone using the Robinson synthesis
Synthesize N-phenylsuccinimide from aniline
Design a route to colchicine skeleton (extremely advanced)
Synthesize p-aminosalicylic acid (anti-TB drug)
Prepare verapamil-like fragment (phenylalkylamine)
Convergent route to tamoxifen (anti-cancer drug)
Synthesizing a bicyclic ketal ring system
Prepare a spirocyclic lactone
Synthesize α-terpineol from limonene

Tips for Practice

Always use a systematic approach and start with the given target structure.
Identify any changes to be made to the carbon skeleton and the functional groups associated with it.
Work in reverse.
As stated, “retrosynthesize” to simpler, more accessible structure fragments or precursors, which are well-known.
Evaluate at least two possible strategies before narrowing down on one.
Take Note of the Following:
Reaction conditions and selectivity region include all categories of selectivity. Regioselectivity, plant anatomy focusing on the real parts of the structure or pattern, stereoselectivity, and others must also be included.
Functionality compatibility and shielding.
Atom economy, step economy, functionally aligned with the objective of enhancing performance efficiency.
Potential side reactions along with over-oxidations that could take place.
Make regular attempts and practice actively. Change each problem that you attempt, including starting materials and reagents, to expand your problem-solving toolkit.

Upon completion of these 120 problems, encompassing foundational transformations, multi-step linear syntheses, retrosynthetic analyses, stereochemical control, named reactions, and advanced convergent strategies, you will have developed a strong problem-solving capability in organic synthesis.

You can access the complete solution here.

You can read about Naming Reactions in Organic Chemistry Class 12 here.

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Ankita Ghosh

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Synthesis Practice for Class 12 – Worksheet – Questionnaire