Q13.44E - Organic Chemistry (Mcmurry)

Question

Propose structures for compounds that fit the following NMR data:

(a)  C₅H₁₀O

0.95$\mathrm{\delta }$(6H,double, J = 7Hz)

2.10$\mathrm{\delta }$ (3H,singlet)

2.43$\mathrm{\delta }$ (1H, mutiplet)

 

(b)  C₃H₅Br

2.32$\mathrm{\delta }$(3H,singlet)

 

5.35 $\mathrm{\delta }$ (3H,singlet)

 5.45$\mathrm{\delta }$(1H, broad signet )

Step-by-Step Solution

Answer

Step 1: 1 H NMR spectroscopy

Different hydrogens exhibit different chemical shift values in the ¹H NMR spectroscopy. ^{Aromatic protons are deshielded and comprise a chemical shift value from 6.5 to .Alkylic protons are shielded and has a chemical shift value from 0.7 to 1.8 ppm.}  

Step 2: Structure of the compound that fits the hydrogen NMR data

(a) The value at 0.95∂ indicated as 1 in the below figure with six hydrogens corresponds to an isopropyl group. The value at indicated as two   with three hydrogens corresponds to a methylketone. The value at 2.43∂ indicated as three with one hydrogen correspond to an isopropyl group. The structure of the compound can be given as:

                                       Structure of compound (a)

(b)The value at 2.32∂ indicated as 1 in the figure denote the methyl group connected to the double bond. The value of 5.35∂and 5.54∂which are the other two hydrogens are the vinylic hydrogen. The structure of the compound can be given as:

                                            Structure of compound (b)