Test: MCQs (One or More Correct Option): Aldehydes, Ketones & Carboxylic Acids | JEE Advanced - JEE MCQ

TIPS/Formulae :

Aldehydes having at least one α-hydrogen atom undergo aldol condensation.

TIPS/Formulae :
Iodoform reaction is given by the compounds containing 
 CH₃CHO and CH₃CH₂OH.2-Hydroxypropane (CH₃CHOHCH₃) contains the grouping CH₃CHOH— and acetophenone (C₆H₅COCH₃) contains the grouping CH₃CO– linked to carbon and hence give yellow ppt. with I₂ and alkali—iodoform test.
In methyl acetate (CH₃COOC₂H₅) and acetamide (CH₃CO–NH₂), CH₃CO is attached to a hetero atom but not to carbon atom and hence both these compounds do not give iodoform test.

NOTE :

Ethyl chloride and acetyl chloride react with alc. KCN by nucleophilic substitution reaction while benzaldehyde undergoes benzoin condensation :

Keto-enol tautomer ism is sh own in compounds having a-hydrogen on the C adjacent to the CO group.

NOTE : Aldehydes and ketones containing a-Hydrogen atom undergo aldol condensation.

TIPS/Formulae :
Three  Cl of chloral makes its carbonyl carbon highly electron deficient, hence H₂O, a nucleophile easily adds on it forming chloral hydrate, CCl₃CH(OH)₂, which is quite stable due to intramolecular H–bonding between two –OH groups.

TIPS/Formulae :
Carbonyl compounds having α – H  or α - D undergo aldol condensation.

(A) Both are soluble in NaOH, hence inseparable.
(B) Only benzoic acid (C₆H₅COOH) is soluble in NaOH and NaHCO₃, while benzyl alcohol (C₆H₅CH₂OH) is not.
Hence, separable.
(C) Although NaOH can enable separation between benzyl alcohol (C₆H₅CH₂OH) and phenol (C₆H₅OH) as only the later is soluble in NaOH. However, in NaHCO₃, both are insoluble. Hence, inseparable.
(D) a-Phenylacetic acid (C₆H₅CH₂COOH) is soluble in NaOH and NaHCO₃. While benzyl alcohol (C₆H₅CH₂OH) is not. Hence, separable.

Aldehydes and a-Hydroxyketones show positive Tollen's test.

Q is steam volatile not R.
Q and R show positive test with 1% aqueous FeCl₃ solution.
Q, R, S give yellow precipitate with 2, 4-dinitrophenyl hydrazine.

LiAlH₄/(C₂H₅)₂O : Reduces to ester s, carboxylic acid, epoxides and aldehydes and ketones.
BH₃ in T.H.F : Reduces to –COOH and aldeh ydes into alcohols but do not reduce to esters and epoxides.
NaBH₄ in C₂H₅OH : Reduces only aldehydes and ketones into alcohols but not to others.
Raney Ni in T.H.F. : Do not reduce to –COOH, –COOR and epoxide but it can reduce aldehyde into alcohols.