ExtractionExtraction is a general theory for the recovery of a substance

from a mixture by bringing it into contact with a solvent which preferentially dissolves the desired material. In organic

chemistry, the reaction product is frequently obtained as a solution in water along with other organic and inorganic

byproducts.

Let’s get started

• To begin this lesson, click on the web address below and view the first 9 pages.

• http://www.slideshare.net/Atharsaeedi/extraction-theory

• Return to this powerpoint after viewing the first 9 pages.

Let’s do the math

By definition, the distribution coefficient is:

concentration in the organic layerconcentration in the water layer

Let us consider compound A:10g of compound A will dissolve in 100ml ethyl ether (an organic compound)2g of compound A will dissolve in 100ml of water

Calculate the KD for compound A

KD=

Determining the KD

concentration in the organic layer = 10g/100ml

concentration in the water layer 2g/100ml

KD= 5

If you are given a solution of 1g of compound A dissolved in 100ml of water, how much could you extract if you did one extraction using 75ml of ethyl ether?

KD=

Set up the problem

Solve for X by cross multiplying two times. Go to the next page to see the value for X.

X = 0.556g

• This means that 0.556g of compound A has now moved to the ethyl ether layer.

• How much compound A remains in the water?• 1g – 0.556g = 0.444g of compound A in the

water.

Try another problem?

• 15g of compound J dissolves in 100ml of benzene.

• 5g of compound J dissolves in water.• You are given a solution with 2g of compound

J dissolved in 100ml of water. If you do one extraction with 50ml of benzene, how many grams of compound A can you extract from the water?

Solve for KD and 1st extraction

In the experiment you will:

• dissolve caffeine in water.• extract the caffeine with chloroform.• do two extractions.

• The math for doing more than one extraction and why it is valuable is the enrichment for this section.