Extraction of Organic Acid

EXTRACTION OF ORGANIC ACID

3. [pic 1]

[pic 2]

Using the Merck index for reference, 1 g of 3-nitroaniline dissolves in 880ml of water and 18ml of ether whereas regarding benzoic acid, one gram of it dissolves in 3 ml ether.

[pic 3]

[pic 4]

[pic 5]

[pic 6]

[pic 7]

[pic 8]

Moles of benzoic acid in water: [pic 9]

2.9 g used above as solubility of benzoic acid in water at 20 C is 2.9 g[pic 10]

[pic 11]

[pic 12]

Therefore, the partition coefficient of 3 nitroaniline is  and of benzoic acid is 115.12[pic 13]

4. To isolate the benzophenone from the mixture, 1gram each of 3-nitroaniline, benzoic acid and benzophenone is used. The mixture is dissolved with dichloromethane followed by pouring the solution into the separatory funnel with the help of a funnel. Then NaOH is added to the same separatory funnel which later would be vigorously shaken with regular intervals of venting out the pressure in the funnel. Later the layers will then separate into two layers with the aqueous layer at the bottom and organic on top, followed by extraction of the aqueous layer into a 125ml Erlenmeyer flask. Then acidify the basic extract with HCL and once solution is acidic, it is cooled until neutral benzoic acid precipitates from the solution. To extract the base, another flask labelled ‘acidic extract’ is used. For this extraction, hydrochloric acid is added to the separatory funnel and then the acidic extract is extracted into the Erlenmeyer flask. Then NaOH is added to basify the extract, and it is basified when the litmus paper turns blue, hence once solution is basic solution is cooled until neutral 3-nitroaniline precipitates from solution. Lastly the third organic layer is extracted into the third flask labelled ‘neutral’ and anhydrous sodium sulfate is added to the flask where the dichloromethane evaporates from the solution and benzophenone precipitate is formed.

5. Reaction mixture consists of 13.2 g KBr and 11.0 g of an interesting organic compound dissolved in 100ml of water. To have the pure organic compound separate from water and salt an extraction is carried out and 100 ml of dichloromethane is added and then shook in a funnel

1. After vigorously shaking the funnel and putting it back on the clamp, the organic layer with dichloromethane will settle at the bottom and water stays at the top as dichloromethane has a higher density than water. Therefore, this an individual can take these steps to determine where the organic layer is located.

1. [pic 14]

[pic 15]

[pic 16]

The partition coefficient with dichloromethane is 1.75

1. WR = Wn   = 1.45 g[pic 17][pic 18]

4 g – 1.45g = 2.55 g extracted

1. P = 1.75

[pic 19]

The recovered compound is 8.56 g

1. WR = Wn  [pic 20]

= 1.07 g[pic 21]

Therefore 1.07 g remains in the aqueous solution and 9.93g is extracted as 11 – 1.07g = 9.93g