#organic synthesis

CHEMISTRY

Which of the following reactions is not used for the preparation of aldehydes?

Friedel-Crafts acylation is used to prepare ketones, not aldehydes. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Chemistry Textbook - Latest Edition for Academic Session 2026-27 (Rationalized Textbook for Class XI and XII)Topic: Mole concept, atomic structure, chemical formulas like H₂O, CO₂, CH₃CH₂NH₂ and periodic trends.

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Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

Which of the following is a product of the Rosenmund reduction of propanoyl chloride?

Rosenmund reduction (H₂,Pd/BaSO₄) converts acyl chlorides to aldehydes. Propanoyl chloride (CH₃CH₂COCl) yields propanal (CH₃CH₂CHO).

Ref: NCERT Class 12 Chemistry > Chapter 12: Aldehydes, Ketones and Carboxylic Acids > Topic: Reactions due to α-Hydrogen - Aldol, Cannizzaro and Acidity of Carboxylic Acids

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Preparation of Phenols and Ethers - Williamson and Other Methods

How is benzyl alcohol synthesized from benzyl chloride?

Benzyl chloride (C₆H₅CH₂Cl) undergoes nucleophilic substitution with aqueous NaOH to replace -Cl with -OH, forming benzyl alcohol (C₆H₅CH₂OH).

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Phenols and Ethers - Williamson and Other Methods

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Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard

Which alcohol can be prepared from an alkene using BH₃ followed by H₂O₂ and OH-?

Hydroboration-oxidation of propene (CH₃-CH=CH₂) follows anti-Markovnikov addition, yielding propan-1-ol (CH₃-CH₂-CH₂OH).

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard

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Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard

Which compound is produced when ethyl magnesium chloride reacts with formaldehyde followed by hydrolysis?

Ethyl magnesium chloride (CH₃CH₂MgCl) reacts with formaldehyde (HCHO), adding the ethyl group to the carbonyl carbon, and hydrolysis yields propan-1-ol (CH₃CH₂CH₂OH).

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard

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Classification and Nomenclature and Structures of Alcohols Phenols Ethers

How is 1-phenylethanol synthesized from a suitable alkene?

Styrene (CH₂=CH-C₆H₅) undergoes acid-catalyzed hydration with H₂SO₄ and H₂O, adding -OH to the more substituted carbon (Markovnikov addition), forming 1-phenylethanol.

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Classification and Nomenclature and Structures of Alcohols Phenols Ethers

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Classification and Nomenclature and Structures of Alcohols Phenols Ethers

How is 2-methylpropan-2-ol synthesized from methyl magnesium bromide?

Methyl magnesium bromide (CH₃MgBr) reacts with acetone (CH₃COCH₃), adding the methyl group to the carbonyl carbon, and hydrolysis yields 2-methylpropan-2-ol ((CH₃)3COH).

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Classification and Nomenclature and Structures of Alcohols Phenols Ethers

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Chemical Reactions of Phenols and Ethers and Uses

Which compound results from the Kolbe’s reaction of phenol?

In Kolbe’s reaction, phenol reacts with CO₂ under basic conditions followed by acidification to form salicylic acid (2-hydroxybenzoic acid).

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Chemical Reactions of Phenols and Ethers and Uses

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Chemical Reactions of Alcohols - Dehydration Oxidation Esterification

What is the product when propan-1-ol reacts with excess conc. H₂SO₄ at 140°C?

At 140°C, propan-1-ol undergoes intermolecular dehydration in the presence of conc. H₂SO₄ to form di-n-propyl ether (CH₃CH₂CH₂-O-CH₂CH₂CH₃). Alkene formation occurs at higher temperature (~170°C).

Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Chemical Reactions of Alcohols - Dehydration Oxidation Esterification

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Elimination Reactions and Reaction with Metals and Other Reactions

Which halide reacts with Na in ether to form a six-carbon alkane with a branched structure?

Wurtz reaction of (CH₃)2CHCH₂Cl (1-chloro-2-methylpropane) forms (CH₃)2CHCH₂CH₂CH(CH₃)2 (2,5-dimethylhexane), a branched six-carbon alkane.

Ref: NCERT Class 12 Chemistry > Chapter 6: Haloalkanes and Haloarenes > Topic: Elimination Reactions and Reaction with Metals and Other Reactions

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Elimination Reactions and Reaction with Metals and Other Reactions

Which halide forms CH₃CH₂CH₂CH₂CH₃ when treated with Mg in ether followed by H₂O ?

CH₃CH₂CH₂CH₂Br forms a Grignard reagent ( CH₃CH₂CH₂CH₂MgBr ), which hydrolyzes to pentane ( CH₃CH₂CH₂CH₂CH₃ ).

Ref: NCERT Class 12 Chemistry > Chapter 6: Haloalkanes and Haloarenes > Topic: Elimination Reactions and Reaction with Metals and Other Reactions

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