Extra NMR Problems

1.  Match the structures to the spectra.

2.  A compound with the formula C4H8O produced the 1H NMR spectrum below. 

(a)  Propose a structure.  (b)  Assign the spectrum.

3.  Determine the structure of the following compounds from the data given.

        (a)  C9H18O   IR:  1670   1H NMR:  0.95, singlet

        (b)  C4H7NO  IR:  2240  1H NMR:  2.63 (2H, triplet), 3.30 (3H, singlet), 3.55 (2H, triplet)

        (c)  C5H12  13C NMR:  27.4, 31.4

        (d)  C5H10O  IR:  1720   13C NMR:  8.0, 35.5, 210.7

        (e)  C4H7N  IR:  2240  13C NMR:  19.0, 19.8, 123.7    1H NMR:  1.33 (6H, doublet), 2.72 (1H, septet)

 

4.  A compound with the formula C4H9Br produced the 1H NMR spectrum below. 

(a)  Propose a structure.  (b)  Assign the spectrum.

5.  Determine the structure and assign the spectrum for each of the following.

Note that problems D and F contain alkynes which exhibit long range coupling.  We did not talk about this in class and you are not responsible for this.

Answers:

1.  Spectrum A:  1,3,5-trimethylbenzene;  Spectrum B:  2-methyl-1-propanol;  Spectrum C:  cyclohexanone;  Spectrum D:  acetophenone;  Spectrum E:  cyclohexene

2.  DU = 1