Question

The 1H NMR spectrum below corresponds to a molecule with the formula C4H5O. Its IR spectrum has important bands at 945, 1015, 1665, 3095, and 3360 cm^-1 Deduce and draw the structure of the unknown compound.

Please answer the question above.

Answer 1

We have C4H8O

degree of unsaturation = ( nC x 2 + 2- nH) /2

           = ( 4 x 2 + 2 - 8) /2 = 1 hence we have 1 double bond

IR peaks confirm C=C peak at 1665 cm-1 and we had H-NMR peaks at 5-6 to confirm this.

Since we had three peaks at C=C H-NMR region we had CH=CH2 as last part.

We had CH3 peaks at 1.4 ppm and OH peak at 1.5 ppm

Joining remaining we get