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

Mixture

Density of CH 2 Cl 2 is 1.33 g/mL CH 2 Cl 2 H2OH2O Methylene Chloride and Water

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

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

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

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

Salts in Water Phase

NH 3 + HClNH 4 + Cl - BaseAcid Salt Ammonia and Acid

Aniline and Acid

Use separatory funnel for separating liquid phases. Separatory Funnel

Hold stopper and stopcock Shake to be sure phases equilibrate

Vent frequently

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

benzoic Acid anthracene NaOH CH 2 Cl 2 anthracene Extract with NaOH

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

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

The benzoic acid is filtered, washed, and dried. Purify Benzoic Acid

Weigh the benzoic acid and measure its melting point. Weight, m.p.

Cool to complete precipitation Precipitate p-Nitroaniline

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

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

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

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

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

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

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 If K = 1.0, a = 10 grams, S2 = 100 mL

Grams extracted vs. number of extractions