13C NMR SPECTROSCOPYOCR Chemistry F324 - 1.3 - Analysis

INTRODUCTION TO CARBON-13 SPECTROSCOPY

➤ Carbon-13 nuclei are ‘spin½’ nuclei, and can hence behave as a magnet.

➤ It can therefore be opposed / aligned to an external magnetic field.

➤ It is possible to oppose the direction by applying a specific amount of energy.

➤ Radio waves are used to supply the energy.

➤ This ‘flipping’ process is known as resonance condition.

EXAMPLE 1

➤ Ethanol:

➤ 2 peaks due to 2 different chemical environments

EXAMPLE 1

➤ Ethanol:

➤ 2 peaks due to 2 different chemical environments.

➤ The first carbon environment (the C on CH3) has the bond

➤ The peak around 20 shows a C-C is present.

➤ The peak around 60 shows a C-O is present.

➤ They are equal heights showing that there are an equal number of carbon environments.

EXAMPLE 2

➤ 1-methylethylpropanoate

➤ 2 peaks due to 2 different chemical environments.

➤ The first carbon environment (the C on CH3) has the bond

➤ The peak around 20 shows a C-C is present.

➤ The peak around 60 shows a C-O is present.

➤ They are equal heights showing that there are an equal number of carbon environments.