Question

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

Short answer

a)

2 signals

b)

One signal

c)

d)

Four types of hydrogens (4 signal)

e)

One signal

f)

Four signals

g)

Three signals

h)

i)

Five signals

j)

Three signals

k)

l)

Three signals

m)

Three signals

n)

Two signals

o)

Three signals

Step-by-step solution

Signals

By identifying the set of hydrogens in a different chemical environment, different types of hydrogen atoms are present in the molecule which exhibits different chemical shifts.

The signals for the given compounds

a)

2 signals

There are two types of hydrogen atoms. Thus, the compound exhibits two signals in the ${}^1\mathrm{H}$NMR spectrum.

b)

One signal

There is only one type of hydrogen atom. Thus, the compound exhibits only one signal in the ${}^1\mathrm{H}$NMR spectrum.

c)

One signal

There is only one type of hydrogen atom. Thus, the compound exhibits only one signal in the ${}^1\mathrm{H}$NMR spectrum.

d)

Four types of hydrogens (4 signals)

Chemical shifts value for four hydrogens

Thus, the compound exhibits four signals in the ${}^1\mathrm{H}$NMR spectrum.

e)

One signal

There is only one type of hydrogen atom. Thus, the compound exhibits only one signal in the ${}^1\mathrm{H}$NMR spectrum.

f)

Four signals

There are four types of hydrogen atoms. Thus, the compound exhibits four signals in the ${}^1\mathrm{H}$NMR spectrum.

g)

Three signals

h)

Three signals

There are three types of hydrogen atoms. Thus, the compound exhibits three signals in the ${}^1\mathrm{H}$NMR spectrum.

i)

Five signals

There are five types of hydrogen atoms. Thus, the compound exhibits five signals in the ${}^1\mathrm{H}$NMR spectrum.

j)

Three signals

There are three types of hydrogen atoms. Thus, the compound exhibits three signals in the ${}^1\mathrm{H}$NMR spectrum.

k)

Four signals

The two geminal protons are different. So, there are four types of hydrogen atoms.

Chemical shift value of 4 protons

Thus, the compound exhibits four signals in the ${}^1\mathrm{H}$NMR spectrum.

l)

Three signals

There are three types of hydrogen atoms. Thus, the compound exhibits three signals in the ${}^1\mathrm{H}$NMR spectrum.

m)

Three signals

There are three types of hydrogen atoms. Thus, the compound exhibits three signals in the ${}^1\mathrm{H}$NMR spectrum.

n)

Two signals

There are two types of hydrogen atoms. Thus, the compound exhibits two signals in

${}^1\mathrm{H}$NMR spectrum.

o)

Three signals

There are three types of hydrogen atoms. Thus, the compound exhibits three signals in the ${}^1\mathrm{H}$NMR spectrum.