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

Mixture of methylene chloride and water Density of CH 2 Cl 2 is 1.33 g/mL CH 2 Cl 2 H2OH2O

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

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

Salts in water phase Neutral organic compounds in the organic phase Water CH 2 Cl 2

Benzoic Acid Sodium Benzoate Treatment of benzoic acid with sodium hydroxide converts it into the salt, sodium benzoate.

NH 3 + HClNH 4 + Cl - BaseAcid Salt

Use separatory funnel for separations.

Shake to be sure phases equilibrate Hold stopper and stopcock

Vent frequently

benzoic Acid p-nitroaniline anthracene HCl CH 2 Cl 2 Benzoic acid Anthracene

benzoic Acid anthracene NaOH CH 2 Cl 2 anthracene

NaOH Filter wash dry weigh HCl Filter wash dry weigh Dry filter evaporate weigh

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

The benzoic acid is filtered, washed, and dried.

Weigh the benzoic acid and measure its melting point.

Cool to complete precipitation

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

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

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

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

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

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

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

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 yields2.5 grams Total 2 extractions with 100 mL = 7.5 grams

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