Nucleophilic addition and addition-elimination reactions

29 questions on Nucleophilic addition and addition-elimination reactions from the Aldehydes, Ketones and Carboxylic Acids chapter: 6 NEET level, 11 JEE Main, 12 JEE Advanced. Each one opens with its answer and solution.

• Chloral (CCl3CHO) forms a stable crystalline hydrate in water mainly because NEET level
• A sample of 60.0 g of formalin, containing 50.0% HCHO by mass, is treated with excess ammonia. Hexamethylenetetramine (CH2)6N4 is obtained in 85% yield based on... JEE Advanced level
• Which of the following statements about nucleophilic addition to carbonyl compounds are correct? JEE Advanced level
• Benzaldehyde is treated with the ylide (C6H5)3P=CHCH3. The products are JEE Main level
• Reactivity of the following towards HCN (nucleophilic addition) increases in the order JEE Advanced level
• Methyl 4-oxopentanoate, CH3COCH2CH2COOCH3, is treated with (i) ethylene glycol, H+, (ii) LiAlH4 then H2O, (iii) aqueous H3O+. The final product is JEE Advanced level
• Which of the following statements about acetals and ketals are correct? JEE Advanced level
• Semicarbazide, NH2NHCONH2, has two NH2 groups but only one takes part in semicarbazone formation, because JEE Main level
• A compound C5H10O gives an orange precipitate with 2,4-DNP, does not reduce Tollens' reagent and gives no yellow precipitate with I2/NaOH. It is treated with CH... JEE Advanced level
• Which reagents convert acetone into a product that contains a C=N bond? JEE Main level
• Which of the following does NOT give an orange-yellow precipitate with 2,4-dinitrophenylhydrazine? JEE Main level
• Which of the following carbonyl compounds form a crystalline adduct with saturated aqueous NaHSO3? JEE Main level
• A mixture of benzaldehyde and benzophenone is shaken with saturated aqueous NaHSO3. Which procedure gives back pure benzaldehyde? JEE Main level
• Which order correctly shows increasing reactivity towards nucleophilic addition of HCN? JEE Main level
• Cyclohexanone is heated with pyrrolidine (a cyclic secondary amine) and a catalytic amount of acid, with water being removed. The product is JEE Main level
• Which of the following is the most reactive towards nucleophilic addition? NEET level
• Propanone reacts with the ylide (C6H5)3P=CH2 (Wittig reaction). The organic product is NEET level
• Ethanal reacts with hydroxylamine, NH2OH, in weakly acidic medium to give NEET level
• The rate of formation of an oxime from acetone and NH2OH is greatest near pH 4.5 and falls at both lower and higher pH. The best explanation is JEE Main level
• Bromomethane is heated with triphenylphosphine, the product is treated with a strong base (n-butyllithium), and the resulting ylide is added to cyclohexanone. T... JEE Advanced level
• A cyclic acetal made from a ketone and ethylene glycol is used as a protecting group. It is stable towards JEE Main level
• Formaldehyde reacts with ammonia to give hexamethylenetetramine (urotropine) with the formula NEET level
• Cyclohexanone reacts with HCN in the presence of a trace of NaCN to give NEET level
• For each pair, the carbonyl compound that is hydrated to the greater extent in water is: (I) HCHO or CH3CHO; (II) CH3COCH3 or ClCH2COCH3; (III) CCl3CHO or CH3CH... JEE Advanced level
• Which of the following statements about imine and enamine formation are correct? JEE Advanced level
• Benzaldehyde reacts with ammonia in the ratio 3:2 with loss of water to form hydrobenzamide (C6H5CH=N)2CHC6H5. Taking C 12, H 1, N 14, its molar mass in g/mol i... JEE Advanced level
• Butan-2-one is allowed to react with various reagents. The correct pairs of reagent and product are JEE Advanced level
• Ethanal is dissolved in excess methanol and dry HCl gas is passed through the solution. The compound that is isolated is JEE Main level
• Compound X reacts with C2H5MgBr, and aqueous acid work-up gives a secondary alcohol Y. Oxidation of Y gives pentan-3-one. X is JEE Advanced level