Nmre ___________________________
1. (5 pts) Match the C-13 spectra below to the small alcohols:
______ CH3CH2 CH2OH 1-propanol
______ (CH3)2CHOH iso propyl alcohol
______ (CH3)2CH CH2OH iso butyl alcohol
Spectrum A all peaks equal size
2. (10 pts) Determine the structure of both of
the following compounds. Indicate what
peaks correspond to which carbons in the
structure.
Molecular
chemical shifts (dept
Formula
results, intensity)
u-up n- not there d-down
three results from bottom
to top on dept spectra.
a) C5H11Cl
22(unu,2) 26(uuu,1)
42(und,1) 43(und,1)
b) C4H8O2
161(uuu,1) 67(uuu,1)
22(unu,2)
Spectrum B right peak twice height of left
Spectrum C right peak twice height of others
1
3. (44 points-4 pts each) Short answers.
ix. At what temperature is the electromagnet kept at?
(include your units)
i) On a 60 MHz instrument, 0.2 ppm in the proton
spectrum corresponds to _______ Hz. On the same
instrument C-13 is run at a frequency of 15 MHz. On
its spectrum, 0.2 ppm corresponds to __________ Hz.
ii) . 1H has a spin of _____ and ____ orientations
where as 2H has a spin of ____ and ____ orientations.
x. The signal to noise ratio on a certain instrument is
15:1 when run on a 5 % solution with 16 scans. On the
same instrument how many scans will it take to get a
signal to noise ratio of 45:1 on a 1 % solution of the
same compound? Show your work.
iii-vi. Consider the NMR of
2 methyl-2- butanol.
iii. Draw the structure of the compound.
xi. Consider the proton spectrum of an ethyl group. The
methylene group, CH2, has a total intensity of 20. What
is the total intensity of the methyl group, CH3, and what
would be the intensity of each line in the spectrum?
iv) The proton spectrum will consist from high to low
chemical shift:
a) a singlet, and a multiplet (splitting greater than 4), a
singlet and a triplet
b) a quartet, and a doublet and a singlet
c) a doublet, a multiplet. and a doublet
d) a triplet, a singlet, and a doublet
e) a singlet, a quartet, a singlet, and a triplet
v. The integration of the peaks from high to low
chemical shift will be:
a) 1:2:6:3 b) 1:1::9:2 c) 2:1:6 d) 4:3:2 e) 1:2:6
vi. The decoupled C-13 spectrum will consist from
high to low chemical shift of:
a) 5 peaks of equal intensity.
b) 4 peaks with one of the middle peaks double the
intensity of the other three.
c) 5 peaks with one of the middle peaks double the
intensity of the other four.
d) none of these
vii. On the Unity plus 500 NMR in S-152, what is the H1 frequency? (include your units)
viii. On the Unity plus 500 NMR in S-152, what is the
C-13 frequency? (include your units)
2
3