Aldehydes and ketones: HCN, NH3 derivatives, Grignard, oxidation, reduction (Wolff-Kishner, Clemmensen)
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See all →- Identify the suitable reagent for the following conversion.Methyl benzoate (Ph-COOCH3) → benzaldehyde (Ph-CHO) Answer: 2. (i) AlH(iBu)₂ (ii) H₂O Key idea: partial reduction of an ester to an aldehyde needs DIBAL-H at low temperature. AlH(i-Bu)₂ follow... 1
- The major product of the following reaction is :Reactant: Ph-CO-CH2CH2-CN; (i) CH_3MgBr (excess); (ii) H_3O^+ Answer: 2. structure (2) Key idea: Grignard reagent adds to both the ketone and the nitrile, but the nitrile adduct is hydrolysed to a keton... 1
- Match List I with List II.List I (Reactions): A. [structure: bicyclohexylidene → 2 cyclohexanone] B. [structure: benzene → benzophenone] C. [structure: cyclohexanol → cyclohexanone] D. [structure: ethylbenzene → potassium benzoate]List II (Reagents/C… Answer: 4. A-IV, B-I, C-II, D-III Key idea: identify the reagent for each conversion. A: alkene to two ketones is ozonolysis, O₃ , then Zn-H... 1
- Identify the correct reagents that would bring about the following transformation.[structure transformation shown in figure: ring-CH_2-CH=CH_2 → ring-CH_2-CH_2-CHO] Answer: 3. (i) BH₃ (ii) H₂O₂/oversetominusOH (iii) PCC Key idea: the -CH=CH₂ group must become -CH₂CH₂CHO , a terminal aldehyde, which needs... 1
- Identify product (A) in the following reaction :3-(3-acetylphenyl)-substituted cyclohexyl methyl ketone: a cyclohexane ring bearing an acetyl group, joined to a benzene ring bearing an acetyl group (meta), [conc. HCl]Zn-Hg (A) + 2H_2O Answer: 2. both acetyl groups reduced to ethyl groups (structure) Key idea: Zn-Hg/conc. HCl is the Clemmensen reduction, which converts >C=O... 1
- Complete the following reaction :cyclohexanone [A] HCN cyclohexanone cyanohydrin (1-hydroxycyclohexanecarbonitrile) [B] [Δ]conc.\ H_2SO_4 [C][C] is ________. Answer: 1. cyclohex-1-ene-1-carboxylic acid (structure) Key idea: Conc. H₂SO₄ with heat does two things to a cyanohydrin: it hydrolyses -CN... 1