Organic Chemistry I

compound 2
is isopropyl ethyl ether.
Compound 3:
• Based on the integration, it is determined that there are:
◦
one CH
3
group show a triplet;
◦
one CH
3
groups show a doublet;
◦
one CH
2
group show a multiplet;
◦
one CH group show a quartet;
◦
one CH
3
group show a singlet.
• The singlet means the CH
3
has no any other hydrogens bonded on adjacent atoms, so the CH
3
group should be
bonded with the oxygen atom, and the value of chemical shift (about 3.2 ppm) confirms.
• The triplet CH
3
could connect with quartet CH
2
as a CH
2
CH
3
ethyl group, that makes sense based on the splitting
pattern.
• The doublet CH
3
groups should connect with a CH group, that is consistent to the splitting pattern.
• The chemical shift (about 3 ppm) and splitting of the CH group (quartet) indicate it should connect to the oxygen
atom.
• Put all the above pieces together, the structure of
compound 3
is sec-butyl methyl ether.
•
Compound 4
• Based on the integration, it is determined that there are:
◦
one CH
3
group show a triplet;
◦
another CH
3
groups show a triplet;
◦
one CH
2
group show a multiplet;
◦
two CH
2
groups with signals overlapping
• The two CH
3
groups both as triplet indicate that they both connect with CH
2
, so there are two ethyl CH
2
CH
3
groups
in the structure, and they are not equivalent.
6.9 Structure Determination Practice | 235

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• Therefore there is only one more CH
2
group left.
• There is only one possible structure with two CH
2
CH
3
groups, one CH
2
group and one oxygen atom, so the
structure of
compound 4
is ethyl methyl ether.
236 | 6.9 Structure Determination Practice

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Answers to Practice Questions Chapter 6