How many signals would you expect to find in the 1H NMR spectrum of each of the following...

How many signals would you expect to find in the 1H NMR spectrum of each of the following compounds?

(a) 1-Bromobutane

(b) 1-Butanol

(c) Butane

(d) 1,4-Dibromobutane

(e) 2,2-Dibromobutane

(f) 2,2,3,3-Tetrabromobutane

 (g) 1,1,4-Tribromobutane

(h) 1,1,1-Tribromobutane

Sample Solution (a) To test for chemical-shift equivalence, replace the protons at C-1, C-2, C-3, and C-4 of 1-bromobutane by some test group such as chlorine. Four constitutional isomers result:

Thus, separate signals will be seen for the protons at C-1, C-2, C-3, and C-4. Barring any accidental overlap, we expect to find four signals in the NMR spectrum of 1-bromobutane.