Chapter 32 - Structure Determination Flashcards
What is NMR and why is it used?
NMR tells us the position of 13C or 1H atoms and their environments, allowing us to deduce the structural formula of a compound
Which of the 2 spectra is more simple to interpret?
13C is simpler, as carbon has less complicated environments, however this does mean it provides less detailed information about the molecule and only the structures of very simple organic molecules can be determined from this alone
What are intergration numbers in 1H NMR?
Integration numbers indicate the relative numbers of 1H atoms in each of the different environments
What must you do to samples to obtain 1H spectra from them?
Dissolve them either in deuterated solvents (solvents where any hydrogen atoms are 2H) or CCl4
What is TMS and why is it used?
TMS is tetramethylsilane is used as the standard for all 1H NMR, because it has a strong and definitive peak at 0ppm always, used it is used to calibrate the rest of the spectra
What is splitting?
Splitting occurs when hydrogen atoms on neighbouring carbon atoms disrupt the magnetic resonance of hydrogens on one carbon, causing a split in the peak of that carbon’s environment. This can be used to determine how many hydrogens are on each carbon by use of the n + 1 rule. For example, a doublet (one peak split into 2) indicates that on a neighbouring carbon there is one hydrogen bond (1H + 1). And on singlets, there are no adjacent hydrogens
What is splitting?
Splitting occurs when hydrogen atoms on neighbouring carbon atoms disrupt the magnetic resonance of hydrogens on one carbon, causing a split in the peak of that carbon’s environment. This can be used to determine how many hydrogens are on each carbon by use of the n + 1 rule. For example, a doublet (one peak split into 2) indicates that on a neighbouring carbon there is one hydrogen bond (1H + 1). And on singlets, there are no adjacent hydrogens
