2. FH2O2Resonance [α]λ SN1E1 ME2SOCl2 TS Enan R. Chem 250-02 Fall, 2014
T BH3 A syN KOtBu SN2
FH2O2Resonance [α]λ
mG (R) E1cb C-HAIR Trans
SN1E1 ME2SOCl2 TS Enan R.

3. CHEM 250-02 Class 39 Thanks for a Really Great Semester
Review Sessions Prof. Keyser – Bring a Question
Tuesday 12/9/ : :00 BC-218
Wednesday 12/10/ : :00 BC-218
FINAL EXAM: Friday 12/12/14
8:30 am - 11:30 am HS-139
Bring your model kits, pencils, (calculator)
Send in questions to Dr. R.

4. Carbon !

6. High Resolution MS Masses can be measured to 1 part in 20,000 !
Masses can be measured to 1 part in 20,000 !
A molecule with nominal mass of 44 could be
C3H8, C2H4O, CO2, or CN2H4.
If a more exact mass is, for example , pick the correct structure from:
C3H C2H4O CO CN2H4

7. Mass Spectra 1-Bromopropane
CH3-CH=CH2 + HBr in air 
MS of Propane CH3-CH2-CH3

8. 1-bromopropane  propene  2-bromopropane 1-bromopropane  propane  2-bromopropane43
CH3CH2CH2-Br
(CH3)2CH+

9. Mass Spectrometry
The presence of Bromine in a compound
The two (2) principal Bromine Isotopes in nature are
Br-79 and Br-81 (2 additional Neutrons in Br-81)
The relative abundance ratio of 79Br to 81Br is : or : or  1 : 1
Molecules containing a single Bromine atom will also show two molecular ion peaks one for Br-79 (M+) and one for Br-81 M+2).
Based on the natural abundance ratio of 100 / (about 1:1), the relative intensity of the 79Br peak will be about the same as the 81Br peak.
Note: Fluorine exists in nature principally as a single isotope - 19F9
Therefore, you will see a single Molecular Ion peak (assuming no other Halogens present).

10. bromotoluene  Methylbenzene  benzylbromide

11. Mass Spectra 1- and 2-Chloropropane43
MS of CH3CH2CH2-Cl

12. Mass Spectrometry
The Presence of Chlorine in a Compound
The two (2) principal Chlorine Isotopes in nature are Cl-35 and Cl-37 (2 additional Neutrons in Cl-37)
The relative abundance ratio of 35Cl to 37Cl is : or : or  3 : 1
Therefore, a Molecule containing a single Chlorine atom will show two Mass Spectrum Molecular Ion peaks, one for Cl-35 (M+) and one for Cl-37 (M+2)
Note: M+2 denotes 2 more neutrons than M+
Based on the natural abundance ratio of 100 / (about 3:1), the relative intensity (peak height) of the Cl-35 peak will be 3 times the intensity of the Cl-37 peak.

13. Mass Spectra C5H12 pentane 2-methylbutane 2,2-dimethylpropane

14. EI MS – Alkanes n-Hexane (C6H14)57
41, 43
27, 29 71

15. EI MS 2,2-dimethylpropane
is the parent ion detected ?

17. Chem Act 16, page 253

18. Chem Act 16, page 254

19. Chem Act 16, page 256

20. Chem Act 16, page 259

23. A New Carbon C60
eI MS

24. 13C 1H
Carboxylic
acids
~ ppm
Aldehydes RCHO
~ 10 ppm

25. Chem Act L-4 Exercise 12. (page 308)
[M]+ = 136 (100) [M+1]+ = 137 (3.3) [M+2]+ = 138 (97.3)
1H NMR: 1.9 (d, 3H)
4.5 (at least 5 lines, apparent pentuplet (?), 1H)
9.7 (d, 1H)

26. Problem 13. 54: Propose a structure and assign peaks
Problem 13.54: Propose a structure and assign peaks. Formula = C4H7O2Cl IR absorption peak at 1740 cm-1
MS m/z 122 (relative intensity 3), 124 (relative intensity 1)

28. Propose a structure consistent with
all of the following data.
t, 3H
q, 2H

30. Problem 13.45b C4H8Cl2

31. Problem 13.58a C5H10O

32. ChemAct L3 Exercise 13 & 14