Question

An organic compound (A) containing C, H, and O (16.32%) does not decolourise bromine water and does not give any precipitate with ammoniacal $AgN{O}_3$. It consumes 1 mol of $N{H}_{2}OH$ per mole of (A) to give a solid derivative. The monobromo derivative of (A) shows optical activity. If (A) is optically inactive, suggest the number of hydrogen atoms present in the structure of compound (A).

Answer 1

Refer image. 1

(A) can be ketone of the type $R-\stackrel{O}{\stackrel{||}{C}}-R$. Percentage of $O=16.32$

Let $R+R=x$ Mw of ketone $=x+12+16=x+28(x+28)$ gm of ketone contains $\Rightarrow \frac{16}{x+28}\times 100$ gm of $O$

$\Rightarrow \frac{16\times 100}{(x+28)}=16.32(.x=70)$

$C_n{H}_{2n+1}=70\Rightarrow 12n+2n+1=70$

$n=\frac{69}{14}\approx 4.9$

Refer image. 2

No. of H-atoms present in the structure of Compound A =10