Q 61P - Organic Chemistry (Mcmurry)

Question

Propose a structure for compound C, which has ${\mathit{M}}^{\mathbf{+}}$= 86 in its mass spectrum, an IR absorption at 3400$\mathit{c}{\mathit{m}}^{\mathbf{-}\mathbf{1}}$ , and the following ${}^{\mathbf{13}}\mathit{C}$ NMR spectral data:

Compound C Broadband-decoupled ${}^{\mathbf{13}}\mathit{C}$ NMR: 30.2, 31.9, 61.8, 114.7, 138.4 d DEPT-90: 138.4 d DEPT-135: positive peak at 138.4 d; negative peaks at 30.2, 31.9, 61.8, 114.7 d

Step-by-Step Solution

Answer

Structure of compound C

$HOC{H}_{2}C{H}_{2}C{H}_{2}CH=C{H}_2$

Step-by-Step Solution Step 1: Mass spectra

It is spectroscopy used to determine the molecular mass of the compound and the structure by plotting the ion signal as a function of mass to charge ratio.

Step 2: Identify compound from mass spectra

As per the given data the molecular ion peak must be at 86 so we can identify the molecular formula that must be $C_5{H}_{10}O$ as per the mass to charge ratio and IR absorption shows it’s an alcohol because of absorption at 3400$c{m}^{-1}$.

Step 3: Structure of compound c

As per the given data the five peaks are observed due to the unsaturated bond and the electronegative atom that is oxygen (o) and the DEPT shoe the compound contains four $C{H}_2$ and one CH atom and mono substituted double bond carbon so,

Structure of compound C

$HOC{H}_{2}C{H}_{2}C{H}_{2}CH=C{H}_2$