Organic II - NMR Spectroscopy Flashcards
How many 1H NMR signals does a benzene ring have?
1
How many 1H NMR signals does pentane have?
3
Chemical shift is measured in ____.
ppm
Upfield is _____ on the graph and downfield is _____ on the graph.
right; left
Upfield has ________ (higher or lower) d
lower
Downfield has _________ (higher/lower) d
higher
What describes the directions on the scale?
Upfield and downfield.
What describes the position of a peak on the ppm scale?
Shielded and deshielded.
Shielded is = to ______.
upfield
Deshielded is = ________.
downfield
Protons that are attached to doubly bonded carbons are _________ (___ ppm).
deshielded (5-7)
Protons attached to triply bonded carbon atoms are _____ shielded (___ ppm)
less; 2
Protons attached to a benzene ring are _________ and appear at about __ ppm.
deshielded; 7
Protons that are more shielded absorb at a _________ field.
higher
The more electronegative atom of a molecule ________ the protons.
deshields
The location of signals show what?
how shielded or deshielded the proton is.
The number of signals show what?
How many different kinds of protons are present.
The intensity of the signal show what?
The number of protons of that type.
Signal splitting shows what?
The number of protons on adjacent atoms.
An ethyl group will contain what kind of signal splitting?
Upfield triplet and downfield quartet.
A singlet has how many neighboring protons?
0
NMR spec of isopropyl is what?
Upfield doublet and downfield septet.
In spin-spin splitting, do equivalent protons split each other?
No.
Is the splitting of CH2 from CH3(CH2)CH2Br a sextet? Why?
No because the neighboring protons are unequivalent… multiplet.
Coupling constants of cis alkene is?
10 Hz
Coupling constants of trans alkene is?
15 Hz
Coupling constants of geminal alkene is?
2 Hz
Coupling constants of ortho protons (besides each other) is?
8 Hz
Coupling constants of meta protons (space b/w p+) is?
2 Hz
In 13C NMR CH is = to _____.
doublet
In 13C NMR CH3 is = to _____.
quartet
In 13C NMR CH2 is = to _____.
triplet
In 13C NMR C is = to _____.
singlet
In 13C NMR, the number of different signals indicate what?
The number of different kinds of carbons.
In 13C NMR, the splitting pattern indicate what?
The number of protons attached to the carbon.
Does DEPT provide the same info as off-resonance decoupling?
yes
DEPT-90 have signals for only ______.
methine (CH) carbons
What has a negative peak in DEPT-135?
CH2 groups.
