Question

Isolation from Caffeine from Leaves lab

Question: Why is it necessary to regulate a gentle reflex for the earlier part of this experiment?

What affect on the caffeine would there be if you ignored this step?

Answer 1

Tea leaves contains following components

Cellulose -the major structural material of all plants

Caffeine -one of the major water soluble substances present in tea leaves stimulates the central nervous system

Tannins -high molecular weight, water soluble compounds that are responsible for the color of tea( To remove tannin add Na2Co3)

Flavonoid pigments -a naturally occurring water soluble phenolic compound belonging to a large group that includes many plant pigments

Chlorophyll -the green pigment in plants that captures the light energy required for photosynthesis

For the extraction of Caffine solvent extraction is one of best method.

Caffine is water soluble so we have to fist dissolve(exteact) in to water. The solubility of caffeine in water is 1. 22 mg/ml at 25⁰ C

                 2. 180 mg/ml at 80⁰ C

                 3.670 mg/ml at 100⁰ C

To get high dissolvation we have to reflux tea leaves with water.

If we ignore this first refluxing step we have to exract with such a solvent which is dissolve caffine highly like dichloromethane (140 mg/ml) but the caffine present in inner part of caffine leaves is not extracted properly. So efficiency extraction of caffine is very low.

So first step to extract in water the by using solvent extraction (dichloromethane, Chloroform, iPrOAc etc. ) you will more caffine.