Acetal, imine and enamine formation

14 questions on Acetal, imine and enamine formation from the Organic Reaction Mechanisms I: Nucleophiles and Carbonyl Addition chapter: 3 NEET level, 5 JEE Main, 6 JEE Advanced. Each one opens with its answer and solution.

• The aldehyde shown is treated with excess methanol in the presence of dry hydrogen chloride. Which structure is the stable final product? NEET level, drawn structure
• The ketone shown reacts with hydroxylamine in weakly acidic medium. Which structure is the product? NEET level, drawn structure
• The aldehyde shown gives an orange-yellow crystalline precipitate when it is treated with 2,4-dinitrophenylhydrazine in acid. To which class does the precipitat... NEET level, drawn structure
• The diol shown is refluxed with cyclohexanone and a trace of toluene-4-sulphonic acid, with removal of water. Which structure is the product? JEE Main level, drawn structure
• The ketone shown is warmed with each amine drawn in the options in the presence of an acid catalyst. Which amine gives an enamine as the stable product? JEE Main level, drawn structure
• The acetal shown is hydrolysed with dilute aqueous acid. Which pair of compounds is formed? JEE Main level, drawn structure
• The cyclic ketone shown is stirred with pyrrolidine and a catalytic amount of acid, with removal of water. Which structure is the isolable product? JEE Main level, drawn structure
• The ketone shown is allowed to react with each reagent below under suitable conditions. Select the reagent(s) that give a product containing a C=N bond. JEE Main level, drawn structure
• The aldehyde shown reacts with a primary amine to give an imine. Select the correct statement(s) about the pH dependence of the rate. JEE Advanced level, drawn structure
• The meso diol shown reacts with benzaldehyde under acid catalysis to give a cyclic acetal (1,3-dioxolane) whose two ring stereocentres derived from the diol kee... JEE Advanced level, drawn structure
• The hydroxy aldehyde shown is dissolved in an excess of methanol containing a catalytic amount of dry HCl. Which structure is the major product? JEE Advanced level, drawn structure
• The ketone shown is stirred with methylamine and sodium cyanoborohydride at pH about 5. Which structure is the major product? JEE Advanced level, drawn structure
• The keto aldehyde shown is treated with one equivalent of ethane-1,2-diol and an acid catalyst (water removed), then with sodium borohydride, and finally with d... JEE Advanced level, drawn structure
• The enamine shown is alkylated with methyl iodide and the product is then hydrolysed with dilute aqueous acid (Stork enamine sequence). Which structure is the f... JEE Advanced level, drawn structure