3.15- NMR

Question 1

What are the 2 main types of NMR

Answer 1

. C13 NMR
.H NMR

Question 2

What determines the amount of peaks in the C13

Answer 2

It depends on equivalent atoms, if there is a different set of equivalent atoms it will have a different peak

Question 3

What determines how many peaks there are in H nmr and the intensity

Answer 3

There is also one peak based on each set of equivalent H atoms, there is also intensity which depends on the ratios fo the equivalent H atoms and there is spin spin coupling

Question 4

What are the different solvents used in NMR

Answer 4

. CCL4, non polar that is a good solvent for non polar molecules
. CDCL3 is a polar covalent molecule that is a good soleveht for polar molecules
.There will be no peals for the H NMR but there is a known peak for C 13 NMR

Question 5

What is used to calibrate the NMR and why

Answer 5

. TMS, tetramethylsilane
. It is used because it only gives one signal, the signal is away from all of the other H signals, it is non toxic, it is intert and it has a low boiling point allowing it to be removed easily

Question 6

What does the peak splitting depend on

Answer 6

In high resoltuion H NMR each signal in the spectrum can be split, the splitting of the peak is equivalent to the number of equivalent Hs on the neighbouring C atoms +1

Question 7

How would you find the molecule if given the IR specturm and the NMR spectrum and Mass spectrujm

Answer 7

. Work out empiritcal formula and finds out the CHO amounts
. Using molecular ion peak from mass spectrum calculate molecular formula
. Using the IR spectrum to identifry all of the main bonds and the functional groups
. Use the NMR spectra to give the details of the carbon chain, lik,e the number of enviorments and the peaks