UPSC Combined Geo-Scientist, Mains · 2022 · Mains Paper III
Q6(c). Birch reduction of benzoic acid
Question
Identify the product (X). Name the reaction and give the plausible mechanism. [benzoic acid treated with Na, liquid NH₃, CH₃OH; structure given in the paper]
Answer in brief
Birch reduction; X = cyclohexa-2,5-diene-1-carboxylic acid (1,4-dihydrobenzoic acid), C₇H₈O₂.
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CoversBirch reductionbenzoic aciddissolving metal reductionsolvated electron1,4-dihydrobenzoic acid
All parts of Question 6
- 6(a) Cyclohexanone: self-condensation with NaOH, none with LDA4 marks
- 6(b) Ethyl acetoacetate with cyclohexanone: Knoevenagel condensation4 marks
- 6(c) Birch reduction of benzoic acid4 marks
- 6(d) HCl with 1-methyl-1-vinylcyclobutane: ring expansion4 marks
- 6(e) Cyclopentadiene with maleic anhydride: endo and exo adducts4 marks
- 6(f) UV absorption of aniline in neutral and in acidic solution4 marks
- 6(g) Aromatic proton shifts: NO₂, COOH and CF₃ as para substituents4 marks
- 6(h) Citral and citronellal by IR: conjugated and isolated C=O4 marks
- 6(i) 3-Methyl- and 4-methylpentan-2-one by mass spectrometry4 marks
- 6(j) 4-Bromobenzoyl chloride to 4-bromoaniline: Lossen rearrangement4 marks