Question

$\xrightarrow{\text{(i) NaSH}}$ M. Find number of hetero atom(s) in 'M'. $\text{(ii) }H_3O^+$

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (B)

2

Answer 2

The reaction involves Michael addition of $SH^-$ to an $\alpha, \beta$-unsaturated ketone, followed by protonation. Assuming the starting material is 2-methylcyclohex-2-en-1-one, the $SH^-$ adds to the $\beta$-carbon (C3) and the proton ($H^+$) adds to the $\alpha$-carbon (C2). The resulting product is 2-methyl-3-mercaptocyclohexan-1-one. The heteroatoms in this molecule are oxygen (O) and sulfur (S). Therefore, there are 2 heteroatoms.