module 6 (p2) Flashcards
what does no neighbouring protons suggest
no change in external magnetic field strength
therefore one peak will be present
what are the -OH and -NH2 bonds in terms of chemical shift peak
labile
can be rapidly exchanged with neighbouring molecules
therefore their chemical shift is variable
how do we remove the labile particles
add D2O
D2O is involved in proton exchange
give the equation for the addition of D2O into a solution of ethanol
CH3CH2OH + D2O <=> CH3CH2OD + HOD
what can be gathered from proton NMR
no. of different proton environments
types of proton environments
relative numbers of each type of proton
non-equivalent protons adjascent to proton
how do we obtain the no. of different proton environments
no. of peaks
how do we obtain the types of proton environments
chemical shift
how do we obtain the relative numbers of each type of proton
ratio number of relative peaks
how do we obtain the non-equivalent protons adjacent to proton
splitting pattern
what does equivalent protons mean
absorb at the same chemical shift
increases the size of peak
what does non-equivalent protons mean
protons have different chemical environments
absorb different chemical shifts
what does the ratio of relative areas under peak give
ratio of number of protons responsible for each peak
what are the relative peak areas within splitting for a singlet, doublet, triplet and a quartet
singlet = 1
doublet = 1:1
triplet = 1:2:1
quartet = 1:3:3:1
what do aromatic protons form
one or more multiplets
what are -NH and -OH
labile protons
have variable chemical shift
how do we remove the chemical shift of OH and NH
add D2O
how does D2O work
exchanges and replaces the protons on OH and/or NH
deuterium doesn’t absorb in chemical range so peak disappears
what are the uses of TLC
forensic testing
quality control
clinical analysis
what is the stationary phase and mobile phase in TLC
SP = silica or alumina
MP = solvent
what do we add when we are doing TLC
lid
for volatile liquids and gases
what are the advantages of TLC
works well with small samples
3x faster than paper chromatography
recovers the sample after
define absorption
how much a surface takes something in
define adsorption
how much something binds to a surface
if a component moves up the TLC plate further, what does this mean about its adsorption
low
