Interpreting NMR spectra
How many proton environments are there
How many hydrogens are there in the peak at approximately 1
How many hydrogens are there in the peak at approximately 3.5
How many hydrogens are there in the peak at approximately 9.5
The formula for this molecule is C3H6O2
Which molecule is consistent with the spectra?
Why is methyl ethanoate clearly not the correct option?
What data lets us differentiate between methanoic acid and ethyl methanoate.
What simple lab test would confirm that an ester was present?
What wet test could be used to confirm that a carboxylic acid was present.
What is the positive results of this test?
Which trough on an IR specta would be present on the carboxylic acid and the the ester?
Which trough on an IR specta would be present on the carboxylic acid but not on the the ester?
How many proton environments are there?
How do we know ? We know that there are three proton environments as there are 3 peaks on the spectrum.
Peak 1 | Peak 2 | Peak 3 | |
|---|---|---|---|
Environment A | |||
Envoronment B | |||
Environment C |
Environment 1
Environment 2
Environment 3
Peak 1 is a
Peak 2 is a
Peak 3 is a
There are
There are
There are
Analyse the spectrum to determine whether this is a spectrum for proponone or propanal.
How could you confirm your conclusion using mass spectra?
What wet tests could you use and what would the results of the test be?
What physical test could you use and how could you use the results to conform your conclusion?
NMR analysis question
(ii) Explain the splitting patterns of the peaks at 4.2 ppm and 1.3 ppm.
4.2 ppm
1.3 ppm
MS.
Origin/start line shown above bottom of paper (1)
Straight line for solvent front added and labelled (1)
Spot due to ethyl-3-oxobutanoate in position consistent with Rf between 0.4 and 0.5 (1)
(ii) Suggest why the Rf value for ethyl 3-oxobutanoate is significantly lower than 0.45 when just hexane is used as the solvent. (2)
M1 As only forces form between them (so spot moves a distance)
ethyl-3-oxobutanoate is , hexane is -polar / (1)
M2 interaction between hexane and ethyl-3- oxobutanoate
/ ethyl-3-oxobutanoate is less in hexane
