organic analysis

what causes splitting?

caused by unidentical hydrogen environments on neighbouring atoms

C13 NMR is easier to interpret as:

no splitting, no integration. we gain information from no. of peaks and shift of the peak

C13 is only 1% abundant, therefore need to do what to sample?

need to use a strong/more sample

number of peaks in C13 =?

number of equivalent carbon atoms

how to check if OH/NH bond present in NMR?

add heavy water (D₂O) which will swap the deuterium with the labile H groups so that the peaks are silenced.

mass spec peak ratios are based on?

probabilities
e.g.
3:1 Cl35:Cl37
1/4×3/4= 3/16
1/4×1/4=1/16
3/4×3/4=9/16
therefore 9:3:1

properties of Si(CH3)4, CCl4 or CDCl3 in mass spec (6)

They are used as solvents
Si(CH3)4 = TMS, which produces one strong sharp peak away from sample peak
CCl4 is not polar so it is effective for non-polar samples
CDCl3 is polar so effective for polar samples
TMS is inert so won’t interfere with sample specctra
TMS is non toxic and can be easily separated from sample due to low boiling point