Complete reaction of acetaldehyde with excess formaldehyde, upon heating with conc. NaOH solution, gives P and Q. Compound P does not give Tollens' test, whereas Q on acidification gives positive Tollens' test. Treatment of P with excess cyclohexanone in the presence of catalytic amount of p-toluenesulfonic acid (PTSA) gives product R.
Sum of the number of methylene groups (−CH2) and oxygen atoms in R is ____.
Answer: 18
Solution
Acetaldehyde undergoes crossed Cannizzaro reaction with excess formaldehyde to give ethanol (P, no aldehyde group, no Tollens' test) and sodium formate (Q, which on acidification gives formic acid that gives positive Tollens' test). Ethanol reacts with excess cyclohexanone in the presence of PTSA (acid catalyst) to form the cyclic acetal. The product R contains 14 methylene groups and 4 oxygen atoms, giving a sum of 14+4=18.
JEE Advanced · 2024 · 26 May 2024 · Paper 1 · Integer answer
