Lab 7 - Caffeine Extraction

Question 1

Caffeine extraction is what type of extraction?

Answer 1

Liquid - liquid extraction

Question 2

True or False
Like dissolve like
Polar substances dissolve in polar substances

Answer 2

True

Question 3

True or False
Non polar substances mostly have O2 in their structures

Answer 3

False
Polar substances mostly have O2 in their structures

Question 4

How do we determine if the substance is at the top layer or at the bottom layer in the seperatory funnel?

Answer 4

Depending on the density, the substance with the lower density will stay up

Question 5

Formula of the partition coefficient?

Answer 5

Molarity/ solubility in organic phase
K= ————————————————————
Molarity/ solubility in aqueous phase

Question 6

Under what conditions will the K be constant?

Answer 6

When we have a specific solvent, temperature and pH.

Question 7

True or False
All tea components are soluble in aqueous solutions, except caffeine.

Answer 7

False
Cellulose is not soluble in water, due to its big size
Tennins is not soluble as it is acidic

Question 8

How can you extract the remaining amount still
present in aqueous phase?

Answer 8

Multiple extractions (repetition)

Question 9

Is caffeine more soluble in water or chloroform?

Answer 9

Chloroform

Question 10

Extraction of Caffeine from Tea leaves:

Answer 10

The components in the tea leaves are:
Cellulose
Tannins
Caffeine
Chlorophyll
Flavonoids

First, we get rid of the cellulose by boiling the tea leaves in water and filtering it

Then we get the aqueous tea extract, which now contains:
Tannins
Caffeine
Chlorophyll
Flavonoids
All of these components are soluble in the aqueous solution except:
Tennins and Caffeine

To get rid of tennins, we add sodium carbonate (a base), which change tennins (slightly acidic) to a salt, the salt can be easily dissolved in the aqueous solution.

Now, we only have the caffeine in the chloroform.
To separate the caffeine from the chloroform, we use the rotary evaporator
In the rotary evaporator, we adjust the temp. of the waterbath to 60°C (the boiling point of chloroform)
The evaporating flask rotate (to increase the surface area), vacuum is applied (to reduce the pressure and the boiling point of the chloroform), the chloroform will evaporate and then pass through the condenser and change to liquid.

Question 11

How does the caffeine act on the body?

Answer 11

It binds to the adenosine receptors in the brain cells causing constriction of blood vessels and stimulation of CNS

Question 12

Effect of adenosine on the body

Answer 12

Adenosine (A) binds to receptors in brain
cells, causing widening of blood vessels
and increase of oxygen supply in brain and
this process helps to prepare the body for
sleep.

Question 13

Between shaking the separatory funnel, why must the pressure be released?

Answer 13

To release the vapour pressure of chloroform

Question 14

Why do we need to shake the sodium sulfate?

Answer 14

To expose it to all the water molecules

Question 15

True or False
Chloroform is toxic and irritating

Answer 15

True