Organic Compounds Containing Oxygen
- Reaction between benzaldehyde and acetophenone in presence of dilute NaOH is known as : Answer: 4. Cross Aldol condensation Benzaldehyde has no α -hydrogen, while acetophenone has α -hydrogens. In dilute NaOH, acetophenone forms... 1
- Reaction between acetone and methylmagnesium chloride followed by hydrolysis will give : Answer: 3. Tert. butyl alcohol Grignard reagents add to the carbonyl group. A ketone gives a tertiary alcohol after hydrolysis. mathrm(CH₃)₂... 1
- The major product of the following reaction is :phthalic acid (benzene-1,2-dicarboxylic acid) + NH_3 strong\ heating Answer: 2. phthalimide (see figure) Phthalic acid reacts with ammonia to give the ammonium salt; strong heating removes water in two steps (... 1
- The compound that is most difficult to protonate is : Answer: 4. Ph-O-H Protonation occurs on the oxygen lone pair; the more available the lone pair, the easier it is to protonate. H₂O , CH₃OH ,... 1
- The structure of intermediate A in the following reaction, is :[Reaction: cumene (isopropylbenzene) O_2 A [H_2O]H^+ phenol + acetone] Answer: 2. (2) cumene hydroperoxide: C6H5-C(CH3)2-O-O-H In the cumene process, cumene is oxidised by air at the benzylic tertiary C-H bond t... 1
- The compound A on treatment with Na gives B, and with PCl_5 gives C. B and C react together to give diethyl ether. A, B and C are in the order Answer: 4. C ₂ H ₅ OH, C ₂ H ₅ ONa, C ₂ H ₅ Cl A is ethanol. C₂H₅OH+Na→ C₂H₅ONa (B), and C₂H₅OH+PCl₅→ C₂H₅Cl (C). B and C then react by Will... 1
- A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. H_2SO_4. The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP will be Answer: 2. 2.8 Conc. H₂SO₄ dehydrates both acids. KOH absorbs CO₂ , so only CO remains. HCOOH→ CO+H₂O : 2.3 g / 46 = 0.05 mol, gives 0.05 mo... 1
- Carboxylic acids have higher boiling points than aldehydes, ketones and even alcohols of comparable molecular mass. It is due to their Answer: 4. formation of intermolecular H-bonding Carboxylic acids form strong intermolecular hydrogen-bonded dimers, so more energy is neede... 1
- Compound A, C_8H_10O, is found to react with NaOI (produced by reacting Y with NaOH) and yields a yellow precipitate with characteristic smell.A and Y are respectively Answer: 2. 1-phenylethanol (C ₆ H ₅ -CH(OH)-CH ₃ ) and I ₂ A positive iodoform test (yellow precipitate with characteristic smell) needs a C... 1
- In the reaction[phenol + CHCl_3 + NaOH → sodium salicylaldehyde (o-O^-Na^+ C_6H_4 CHO), shown as a structure]the electrophile involved is Answer: 4. dichlorocarbene (:CCl ₂ ) This is the Reimer-Tiemann reaction. The electrophile is dichlorocarbene. The base removes a proton fro... 1
- Consider the reactions :X\ (C_2H_6O) Cu/573\ K A [Ag(NH_3)_2]^+,\ ^-OH,Δ Silver mirror observed; A ^-OH,Δ Y; A NH_2-NH-C(=O)-NH_2 ZIdentify A, X, Y and Z Answer: 2. A-Ethanal, X-Ethanol, Y-But-2-enal, Z-Semicarbazone. Key idea: C₂H₆O with Cu/573 K dehydrogenation means a primary alcohol. X = e... 1
- Of the following, which is the product formed when cyclohexanone undergoes aldol condensation followed by heating ? Answer: 1. [structure: 2-cyclohexylidenecyclohexanone] Key idea: aldol condensation = aldol addition followed by loss of water on heating, g... 1
- The heating of phenyl-methyl ethers with HI produces. Answer: 2. phenol Key idea: HI cleaves an aryl alkyl ether at the alkyl-oxygen bond. C₆H₅OCH₃ + HI → C₆H₅OH + CH₃I . The oxygen is protonate... 1
- Which one is the most acidic compound ? Answer: 3. [structure: 2,4,6-trinitrophenol] Key idea: electron-withdrawing groups stabilise the phenoxide ion and increase acidity. 2,4,6-T... 1
- Mixture of chloroxylenol and terpineol acts as : Answer: 1. antiseptic Key idea: a chloroxylenol and terpineol mixture is the well-known disinfectant Dettol. It is used on skin and wounds t... 1
- The correct structure of the product A formed in the reaction [cyclohex-2-enone, H_2 (gas, 1 atmosphere), Pd/carbon, ethanol → A] is Answer: 1. [structure shown in figure] Key idea: H₂ with Pd/C at 1 atm reduces the C=C bond selectively; the C=O is not reduced under these... 1
- The correct order of strengths of the carboxylic acids [I, II, III shown] is Answer: 1. II > III > I Key idea: an electron-withdrawing atom near COOH stabilises the carboxylate and raises acidity; the effect weakens w... 1
- Which of the following reagents would distinguish cis-cyclopenta-1, 2-diol from the trans-isomer ? Answer: 1. Acetone Key idea: only the cis-1,2-diol has both -OH groups on the same side of the ring, so it can form a cyclic five-membered k... 1
- The product formed by the reaction of an aldehyde with a primary amine is : Answer: 1. Schiff base Key idea: an aldehyde (or ketone) condenses with a primary amine with loss of water to give an imine, R-CH=N-R' , als... 1
- The reaction[cyclopentanol, then NaH giving sodium cyclopentoxide, then Me-I giving methyl cyclopentyl ether; scheme shown in figure]can be classified as : Answer: 1. Williamson ether synthesis reaction Key idea: an alcohol is converted by a strong base (NaH) into an alkoxide, which then attacks... 1
- The correct statement regarding a carbonyl compound with a hydrogen atom on its alpha-carbon, is : Answer: 4. a carbonyl compound with a hydrogen atom on its alpha-carbon rapidly equilibrates with its corresponding enol and this process is... 1