Question

Describe the ¹H NMR spectrum you would expect for each of the following compounds, indicating the relative positions of the signals:

Short answer

a.

b.

c.

d.

e.

f.

g.

h.

i.

j.

k.

l

m.

n.

o.

p.

Step-by-step solution

Splitting patterns in NMR spectroscopy

NMR shows a different number of peaks. These are called the splitting patterns in NMR spectroscopy. We know that the simplest signal consists of one line is called a singlet, followed by a doublet, triplet, quartet, and multiplet.

Spitting is caused by the hydrogens on the same or neighboring carbons. Only non-equivalent protons cause splitting.

Position of signals in compounds

(a)

As the compound contains a plane of symmetry so the splitting pattern in the compound is as follows;

Compound (a)

Each spectrum is described going from left to right. It shows triplet, triplet.

(b)

-CH₃the group next to oxygen shows singlet. While as we move from left to right the -CH₂ group shows triplet, multiplet, and triplet.

Compound (b)

(c)

The given molecule contains a plane of symmetry so all the hydrogens are equivalent and show singlet.

Compound (c)

(d)

The left side -CH₃group shows singlet while the right side one shows triplet.-CH₂ group show quartet.

Compound (d)

(e)

In the given structure all the -CH₃ and the -CH₂group show singlet as no neighboring hydrogen is present for the coupling.

Compound (e)

(f)

In the given structure two hydrogens showa doublet while one shows a doublet of the doublet.

Compound (f)

(g)

The molecule contain plane of symmetry. The -CH₃group shows triplet while the -CH₂group shows quartet.

Compound (g)

(h)

The -CH₃ group show triplet and the CH₂ next to it shows quartet. While group in between chlorine and oxygen shows singlet.

Compound (h)

(i)

As we move from left to right we see doublet, multiplet, and doublet

Compound (i)

(j)

The oxirane shows triplet and quartet as shown below;

Compound (j)

(k)

In the following molecule -CH₃ shows doublet and -CH shows multiplet.

Compound (k)

(l)

The molecule contains a plane of symmetry -CH₃ shows singlet while -CH₂ shows triplet and multiplet as shown below;

Compound (l)

(m)

The hydrogen shows singlet.

Compound (m)

(n)

Both the hydrogen shows singlet as shown below;

Compound (n)

(o)

In cyclopentane, all shows singlet.

Compound (o)

(p)

In 1-chloropentane we observe multiplets.

Compound (p)