1. Extractions
Mixture of benzoic acid, anthracene, and p-nitroaniline

2. Structures

3. Mixture of methylene chloride and water
Density of CH2Cl2 is 1.33 g/mL
H2O
CH2Cl2

4. Salts
If we dissolve NaCl in this mixture which phase has the highest salt concentration?
Salts concentrate in the water layer

5. Neutral Organic Cpds
If we dissolve benzoic acid in this mixture in which phase would it concentrate?
Neutral organic compounds concentrate in the organic phase
Salts

6. Salts in water phase Water CH2Cl2
Neutral organic compounds in the organic phase
CH2Cl2

7. Treatment of benzoic acid with sodium hydroxide converts it into the salt, sodium benzoate.

8. Distribution

9. NH HCl
NH4+ Cl-
Salt
Base
Acid

10. Distribution

11. Use separatory funnel for separations.

12. Shake to be sure phases equilibrate
Hold stopper and stopcock

13. Vent frequently

14. benzoic Acid p-nitroaniline anthracene HCl CH2Cl2 Benzoic acid
Procedure

15. benzoic Acid
anthracene
NaOH
CH2Cl2
anthracene
Procedure

16. HCl NaOH Dry filter evaporate weigh Filter wash dry weigh
Procedure

17. Addition of acid to the sodium benzoate solution causes benzoic acid Add Acid to precipitate.

18. The benzoic acid is filtered, washed, and dried.
Filter, wash, dry

19. Weigh the benzoic acid and measure its melting point.
Weigh, mp

20. Cool to complete precipitation

21. Dry with sodium sulfate
Dry the methylene chloride solution of anthracene with a small amount of sodium sulfate.
Dry with sodium sulfate

22. Remove the drying agent by filtration through a fluted filter paper.

23. Evaporate methylene chloride
Evaporate the methylene chloride on a steam bath.
Use an inverted funnel connected to the vacuum line to collect the vapor.

24. Put your samples in labeled vials and give them to your TA.
Weigh your products and measure their melting points.
Put your samples in labeled vials and give them to your TA.

25. Partition Coefficients
10 g t-butyl alcohol
100 mL ether
100 mL water

26. 10 grams t-butyl alcohol x g / 200 mL 2.2 = ( 10 - x)g / 100 mL
x = 8.1 grams

27. Which is better?
Extract once with 200 mL or twice with 100 mL?

28. If K = 1.0, a = 10 grams, S2 = 100 mL
Extract once with 200 mL yields 6.7 grams
Extract once with 100 mL yields 5.0 grams
Second extraction with 100 mL yields
2.5 grams
Total 2 extractions with 100 mL = 7.5 grams

29. Grams extracted vs. number of extractions for K = 1, 2 and 4