EFT 60 facts

H frequency- 60 MHz

C-13 frequency -15 MHz

Field is 1.38 Tesla or 13800

Permanent Magnet that operates at 27 C

Ethanol H-1 spectrum on EFT 60

Unity Plus 500 NMR Facts

H frequency- 500 MHz

C-13 frequency -125 MHz

Field is 1.38*500/60 = 11.5 Tesla or 115000 Gauss

"Electromagnet" that operates at 4 K. (-269 ^oC).

The Chemical Shifts are the same as the EFT 60 in ppm and the J values are the same in Hz.

Ethanol H-1 spectrum on Unity Plus 500

Note:

1) The peaks appear at about the same chemical shift in both spectra. The would be exactly the same if the same sample were run on both.

2) The splitting of the peaks appears to be greater for the low field instrument. The is to some extent an illusion in that the splitting is the same in Hz (about 10 Hz) but on the EFT 60 10 Hz is .17 ppm (the distance between adjacent peaks) where as 10 Hz is .02 ppm on the Unity plus 500!

3) The peaks from hydrogens on different carbons appear to be separated more from one another in the spectrum of the unity plus 500. This results primarily from the splitting being less in ppm (in other word from the same reason as in 2 above).

Principles Lab.

Take a proton NMR of n-Butanol (3-96) on both the EFT 60 and the Unity plus 500. On both instruments, plot a “normal” spectrum and plot an expanded (one that cuts out the parts of the spectrum with no peaks). Write up your results. Your write up should include a summary table for each spectrum. In what ways are the spectra the same and have the same information. In what ways are they different.

Homework

1. Nuclear Overhauser Effect, n.o.e., is:

a) the name given to the reason magnetic moment preccess in a magnetic field.

b) the effective coupling between one nuclei and a neighboring nuclie

c) the enhanced intensity one gets in a C-13 spectrum when the H attached to it is decoupled.

d) the effect one gets by giving a nuclei a 180 degree pulse.

2. For a proton spectrum on a 60 MHz instrument, 1 ppm corresponds to ____ Hz.

3-5. Consider the NMR of 3-pentanone (CH₃CH₂)CO.

3. The proton spectrum will consist (from high chemical shift to low) :

a) a singlet, and a multiplet (splitting greater than 4) and a triplet

b) a quartet, and a triplet.

c) a two doublets and two triplets..

d) two triplets and two quartets

e) a triplet, and a doublet

4. From the highest chemical shift to the lowest, integration of the peaks in the proton spectrum will be:

a) 2:3 b) 2:2:3:3 c) 1:2:3

d) 3:2:2:3 e) none of these

5. The decoupled carbon spectrum will consist of ____ peak(s).

a) 2 b) 3 c) 4 d) 5 e) none of these.

6. The proton frequency on a magnet with a field of 200 MHz is 46000 gauss. What is the field strength on an instrument when the proton frequency is 60 MHz?

a) 13800 gauss b) 153333 gauss c) 4140 gauss d) none of these

Consider ethyl benzene; C6H5CH2CH3

(a) (b) (c)

7. The b protons in the proton spectrum will be :

a)a 1:2:1 triplet b)a 1:3:3:1 quartet

c)a 1:1:1 triplet d) a 1:1 doublet

e) none of these

8. The c protons in the proton spectrum will be :

a)a 1:2:1 triplet b)a 1:3:3:1 quartet

c)a 1:1:1 triplet d) a 1:1 doublet

e) none of these

9. In the decoupled C-13 spectrum the 6 carbons of the phenyl ring will show up as :

a) 6 peaks of equal intensity

b) 5 peaks of equal intensity and one of low intensity

c) 4 peaks of equal intensity

d) 4 peaks- two of larger intensity and two of lower but not necessarily equal intensity

10-12 Match these alcohols and their C-13 spectra.

______ CH₃CH₂OH ethanol

______ CH₃CH₂ CH₂OH n-propanol

______ (CH₃)₂CHOH i-propanol

Spectrum a -all peaks equal size

Spectrum b -right peak twice height of left

Spectrum c.