1. 4. Prelab Radical Bromination of p-Toluic acid
BOSTON UNIVERSITY
DRESDEN SCIENCE PROGRAM
ORGANIC CHEMISTRY LABORATORY
CAS CH 203, FALL 2018
4. Prelab Radical Bromination of p-Toluic acid

2. Radical Bromination of p-Toluic acid
You will be conducting two different experiments:
Radical bromination of p-toluic acid
2. Test of radical bromination of different hydrocarbons
Halogenes (chlorine and bromine) can react with saturated hydrocarbons only via free radical substitution reaction. Alkyl or cycloalkyl halides are formed.

4. Part 2: Test of radical bromination of hydrocarbons/ radical stabilty
The hydrocarbons that will be tested are cyclohexane, methylcyclohexane, toluene (methyl benzene),
ethylbenzene, isopropylbenzene (cumene), and t-butylbenzene.
Radical stability
3° benzylic > 2° benzylic > 1° benzylic > 3° aliphatic > 2° aliphatic > 1° aliphatic > aromatic

5. Safety and hazards:
Bromine
N-bromosuccinimide
Benzoyl peroxide
Potassium bromate
Hydrochloric acid
Chlorobenzene
Petroleum ether
Hydrocarbons (general)
Benzyl halides (general)

6. Bromine Formation / Bromide-Bromate- Reaction
5 KBr + KBrO3 + 6 HCl  3 Br2 + 3 H2O + 6 KCl

7. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 3 – Reaction Methods

8. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 3 – Reaction Methods

9. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 8 – Simple Distillation

10. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

11. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

12. Exp. 13B - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

13. Exp. 13B - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

14. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

15. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

16. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

17. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

18. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents
Extraction:
Supposed system:
K = 10,
50 mg compound in 1 mL water (solvent 1)
3 x extraction with 0.5 mL ether (solvent) each in comparison to 1 x extraction with 1.5 mL ether
x = amount remaining in the aqueous phase
Distribution
coefficient

19. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

20. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

21. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Technique 7 – Extractions, Separations, and Drying Agents

22. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Appendix 3 – IR Spectroscopy
wavenumber unit: cm-1

23. Exp. 4 – Synthesis of 4-(bromomethyl)benzoic acid
Appendix 3 – IR Spectroscopy

24. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid Appendix 3 – IR Spectroscopy

25. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Appendix 3 – IR Spectroscopy

26. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Appendix 3 – IR Spectroscopy

27. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Appendix 3 – IR Spectroscopy
IR Spectra of 4-methylbenzoic acid and 4-(bromomethyl)benzoic acid

29. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
NMR- Spectra of p-Toluic acid

30. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
NMR- Spectra (calculated)

31. 4-methylbenzoic acid
4-(bromomethyl)benzoic acid

32. 4-methylbenzoic acid
4-(bromomethyl)benzoic acid

33. Exp. 4 - Synthesis of 4-(bromomethyl)benzoic acid
Appendix 3 – IR Spectroscopy