SPECTROSCOPY FINAL EXAM WITH VERIFIED
ANSWERS #7
Which functional group gives a 1H NMR integration of .5 much lower than 1 - correct
answer That would be an aldehyde because there is a lot of electron withdrawing
occuring here
Why is a aldehyde more deshielded than an ester or carboxylic acid - correct answer
Esters and carboxylic acids are resonance stabilized
On a COSY you may see splash due to - correct answer T1 noise and instrumental
instability
1D advantages - correct answer Less data sets
Less time needed
1D disadvantages - correct answer Need well separated peaks and need a sample at
every frequency
COSY retains - correct answer J value information
Often seen in COSY - correct answer Long range coupling
Dipolar coupling - correct answer Direct through space coupling
NOE give info about - correct answer Stereochemistry and relative distances within the
system
Spin spin splitting for Vicinal or next door neighbors is due to - correct answer Dihedral
angle
Trans-diaxial - correct answer 180 dihedral angle
Larger coupling in COSY - correct answer Larger dihedral angle
A noisy does not show - correct answer Through bond coupling only what's directly
close in soace
Maximum coupling with dihedral angle of - correct answer 0 or 180
Higher magnetic field - correct answer Better resolution
J values are - correct answer Individual lengths in Hz between to two peaks
Avoid distortion by - correct answer Delta v / J greater than or equal to 8
ANSWERS #7
Which functional group gives a 1H NMR integration of .5 much lower than 1 - correct
answer That would be an aldehyde because there is a lot of electron withdrawing
occuring here
Why is a aldehyde more deshielded than an ester or carboxylic acid - correct answer
Esters and carboxylic acids are resonance stabilized
On a COSY you may see splash due to - correct answer T1 noise and instrumental
instability
1D advantages - correct answer Less data sets
Less time needed
1D disadvantages - correct answer Need well separated peaks and need a sample at
every frequency
COSY retains - correct answer J value information
Often seen in COSY - correct answer Long range coupling
Dipolar coupling - correct answer Direct through space coupling
NOE give info about - correct answer Stereochemistry and relative distances within the
system
Spin spin splitting for Vicinal or next door neighbors is due to - correct answer Dihedral
angle
Trans-diaxial - correct answer 180 dihedral angle
Larger coupling in COSY - correct answer Larger dihedral angle
A noisy does not show - correct answer Through bond coupling only what's directly
close in soace
Maximum coupling with dihedral angle of - correct answer 0 or 180
Higher magnetic field - correct answer Better resolution
J values are - correct answer Individual lengths in Hz between to two peaks
Avoid distortion by - correct answer Delta v / J greater than or equal to 8
