Question 17.6.1: Predict the number of signals and multiplicity of the respec......

(i) One signal    Singlet as all hydrogens are equivalent

(ii) $Cl— \overset{a}{CH_2}— \overset{b}{CH_2}— \overset{a} {CH_2}—Cl$

2- signals; signal of $CH_2$ (b) appears as a quintet (5 peaks n +1 rule; 4 + 1 = 5 and that of $CH_2$ (a) protons as a triplet (n+1 rule; 2 + 1=3)

(iii)  $\begin{matrix}^a CH_2 &—& O\\ |  &\quad & | \\^bCH_2& —&\underset{a}CH_2\end{matrix} \quad \quad$

2–signals     A four proton triplet and a two proton quintet (5 peaks)

(iv)$\quad \begin{matrix}\overset{b}{CH_3}& \quad \\ \quad \quad {\diagdown} & \quad \\ \quad & \overset{a}CH—C≡N\\ \quad \quad \diagup & \quad \\\overset{b}{CH_3} & \quad \end{matrix}\quad$

2– signals   A six proton doublet and a one proton septet

(v)  $\begin{matrix} \overset{c}{CH_3} &  & \quad \overset{a} H\\ \quad \quad \diagdown & & \diagup \quad \\  & C \xlongequal[]{} C &  \\  \quad \quad \diagup &  & \diagdown \quad \\ Cl &  & \underset{b}H \end{matrix}$

3– signals    $H_a$ and $H_b$ cause splitting of signals and each appears as a doublet. $CH_3$ appears as a singlet.