NMR

Question 1

What is TMS

Answer 1

This is an internal standard for both carbon and proton NMR

Question 2

What is chemical shift

Answer 2

This is the scale that compares the frequency of NMr absorption with the frequency of the refernce peak TMS

Question 3

What is deuterium

Answer 3

This is an isotope of hydrogen and does not produce a signal in the proton NMR spectrum

Question 4

NMR is a ..

Answer 4

Non destructive analytical technique

Question 5

Describe how nuclear magnetic resonance work

Answer 5

• some isotopes such as H1 and C13 have a property known as spin
• organic compounds put in a large magnetic field, the direction or these nucleons align with the direction of the magnetic field
• energy required to change alignment depends on the environment that the atom is in and can be compared to a standard

Question 6

What is the tms peak

Answer 6

0ppm

Question 7

What is a tms used for

Answer 7

Used to compare the values in the sample

Question 8

Why is tms a good internal standard

Answer 8

• contains both carbon and hydrogen so can be used for carbon and proton NMR
• produces one sharp signal as hydrogen atoms are in a single environment, as there is only one carbon atom this will also produce one signal in carbon-13 NMR
• it is non toxic
• low boiling point and volatile so it can easily be removed from the sample
• it is inert so is unlikely to react with chemical that is being investigated