1. Spectroscopy of Organic Compounds
CHEM 344
Organic Chemistry Lab
Spectroscopy of Organic Compounds
Lecture 1 - Intro to NMR
Why are we here and not in the lab?
Section rosters at front
Introduce Matt and TAs
Problem sets after lectures 1, 2, 3
Lab manual and notebooks, and textbook
Course intro/safety on Thurs + lab check-in
Nick Hill
June 16th 2008

2. ………the eyes of the chemist
Spectroscopy…….
Define Spec
Use “eye” analogy
Low energy process….low energy radiation
………the eyes of the chemist

3. Speed of light (c) is constant for all wavelengths
Frequency (n), the number of wavelengths per second, is inversely proportional to wavelength:
n = c/l
Energy of a radiation is directly proportional to frequency
E = hc/l = hn
This should be review!!!

5. NMR MS
Spectroscopy IR
Spectrometry !!

7. 900 MHz instrument at NIH site = approx 20 T

8. Proton and Carbon NMR spectroscopy
Spin ½ atoms 1H, 13C
Spin 1 atoms 2H (D), 14N
Proton and Carbon NMR spectroscopy
Spin 0 atoms C, 16O, 32S

9. 2.29
Chemical shift
7.04 Ha Hb 6
Integration 4
SiMe4

10. 3.75 Ha
6.82 Hb 6
Mention CHCl3 in CDCl3 4
CHCl3
SiMe4

11. 1.50 Ha
Downfield 9
Deshielded
Upfield Hb
Shielded
8.00 1

12. 2.29
7.04 Ha Hb 6 4

13. 3.75
6.82 Ha Hb 6 4

14. 3.75
6.82 Ha Hb 6 4

15. 2.45 Ha
4.56 Hb 9
Another example of shielded/deshielded protons 6

16. Just a reminder about CHCl3

17. 0.87 Ha 9
Amine signal broad due to exchange broadening – chem shift is variable
Liken to camera shutter…….to ofast for NMR timescale - this also applies to OH protons (such as in COOH, ROH)
H-bonding effects also very important
2.42
NH2
1.04 Hb 2 2

18. 2.14
5.80 3
Note diff in chem shift for Me bound to C=O vs. CH2Br 2

19. 3.66
2.05 3 3
Which is which? Example where need knowledge of chem shift, since integration no use
Previous slide: Me bound to C=O was ~2.1 ppm
Earlier slide: OCH3 in 1,4-dimethoxybenzene was ~3.7 ppm

20. 0.08
2.04 9
3.76 3 2