Title 2.Carbonyl Compounds (Pass. Q.).pdf ✅

1 CHEMISTRY Passage –I Aldehyde without –H atoms on reaction with concentrated alkali solution undergo an oxidation- reduction (disproportionation) reaction. One half of the aldehyde is reduced to a 1° alcohol and the other is oxidised to a carboxylic acid. This is known as Cannizzaro reaction. 2–C–H O ⎯50⎯%⎯NaOH⎯→ – CH2 OH + –C–O–Na O   (no –H) Two steps are involved in this reaction. (i) Attack of OH ion on the carbonyl group of one aldehyde yields an oxyanion. H–C–H + OH O H–C–H O  OH (oxyanion) (ii) As a result of hydride transfer, the final product is formed H–C–H O  OH C = O H H + H–C + CH3O  O OH Proton exchange H–C–ONa + CH3OH O – + Na H–C + CH3OH O O  Intramolecular Cannizzaro’s reaction is also possible CHO CHO ⎯NaOH ⎯⎯→ CH2OH COONa Q.1 The aldehyde which shows Cannizzaro’s reaction is - (A) HCHO (B) C6 H5 CHO [D] (C) CCl3 –CHO (D) all of thes Q.2 The product formed in the following reaction will be - CHO CHO ⎯NaOH ⎯⎯→ product - (A) CH2OH CH2OH (B) CH2OH COONa (C) COONa COONa (D) All of these [B] Q.3 Mixture of C6 H5 CHO and HCHO is treated with NaOH then cannizzaro’s reaction involves - (A) Oxidation of HCHO (B) Reduction of HCHO and Oxidation of C6 H5 CHO (C) Reduction of C6 H5 OH (D) Both A & C [D] Passage –II Aldehydes and ketons are specially susceptible to nucleophilic addition because carbonyl group C = O is polar (due to electronegativity difference between carbon and oxygen). + C = O – Positive charge on carbon makes it reactive towards the nucleophile. This addition is catalysed by acid. Reactivity of carbonyl compound towards nucleopilic addition increases with increase in the electron deficiency at carbonyl carbon. Thus, (– I.E.) groups increase while (+ I.E.) groups decrease the reactivity of carbonyl compound. Answer the following questions : Q.4 Which among the following is most reactive to give nucleophilic addition ? [D] (A) FCH2 CHO (B) CICH2 CHO (C) BrCH2 CHO (D) ICH2 CHO Atomic Structure (M.C.Q.)