CARBONYL COMPOUNDS

Which of the following is not a carbonyl compound?

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An organic compound X has the following chemical properties.

· Forms a yellow precipitate when tested with 2,4-dinitrophenylhydrazine.

· Forms a yellow precipitate when it reacts with an excess iodine in alkaline solution.

Which of the following compounds is X?

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Which of the following alcohols can be oxidised to 2-methyl-3-pentanone?

• CH₃CH₂CH(OH)CH₃

• CH₃CH(OH)CH₂CH₂CH₃

• (CH₃)₃CCH(OH)CH₃

• (CH₃)₂CHCH(OH)CH₂CH₃

The following reaction scheme shows how propene can be prepared from propanal in two stages using reagents X and Y. Which of the following are the reagents X and Y?

X Y

CH₃CH₂CHO → CH₃CH₂CH₂OH → H₃CH=CH₂

• X: LiAlH₄ ; Y: KOH, ethanol, reflux

• X: NaBH₄ ; Y: conc.H₂SO₄, heat

• X: dillute H₂SO₄ ; Y: conc.ethanol, reflux

• X: dillute H₂SO₄ ; Y: KOH, ethanol, reflux

On heating compound X with acidified KMnO₄, compound Y is obtained. Compound Y does not react with Fehling’s solution. X and Y are most likely to be,

Compound X Compound Y

• CH₃COCH₃ CH₃COOH

• CH₃CH(OH)CH₃ CH₃COCH₃

• CH₃CH₂CH₂OH CH₃COCH₃

• CH₃CH₂CH₂OH CH₃CH₂CHO

Which substance would test positively with 2,4-DNPH but negatively with Tollens’ reagent?

• Propanal

• Propanone

• Propanoic acid

• 1-propanol

Acetone reacts with HCN to form a cyanohydrin. It is an example of

• Electrophilic addition

• Electrophilic substituition

• Nucleophilic addition

• Nucleophilic substituition

Which reagent would you choose to convert 1-pentanol to pentanal?

• PCC in CH₂Cl₂

• K₂Cr₂O₇ with aqueous H₂SO₄

• KMnO₄ with aqueous H₂SO₄

• KOH, ethanol, reflux

Which statement about butanone is correct?

• The C=O of butanone is polar with O δ^–

• Butanone can be prepared by reduction of 1-butanol

• Butanone forms brick red precipitate with Fehling’s reagent

• Butanone form cloudy solution with Lucas test

What is the reagent to differentiate between a benzaldehyde and a ketone

• Acidified potassium dichromate (VI) solution

• Tollen’s reagent, [Ag(NH₃)₂]⁺

• Fehling’s solution containing complex ions of Cu²⁺