Pharmaceutical Organic Chemistry: Lactose Isolation Experiment, Assignments of Pharmaceutical Analysis

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MODULE: PHARMACEUTICAL ORGANIC CHEMISTRY

Please answer the questions below

1. State the aim of this experiment

For students to familiarize themselves with the principles and skills involved in isolation of a lactose from milk.

2. Define the term extraction? Extractions are a way to separate a desired substance when it is mixed with others. The mixture is brought into contact with a solvent in which the substance of interest is soluble, but the other substances present are insoluble. 3. Why is lactose more soluble in water than in ethanol? Because of presence of free hydroxy groups in lactose it will forms more hydrogen bonds with water than ethanol, so it is more soluble in water than ethanol. 4. Why does a disaccharide molecule not have exactly the molecular weight of 2 monosaccharide molecule? This is because the disaccharide molecule may consist of two different monosaccharide molecules such as lactose (galactose-glucose) which have different masses. With similar sugars like maltose (glucose-glucose) it’s due to the glycosidic bond formed when hydrogen and oxygen combine to form water. The disaccharide is formed by a condensation reaction of 2 monosaccharide molecules in which a small molecule (like water) is eliminated. 5. What were the roles of following (a) Discolouring carbon (activated charcoal) To remove coloured impurities from the crude organic product (b) Sodium carbonate (calcium carbonate)? To neutralize the excess acid after separation of casein from whey. 6. In step 3, you were cautioned not to add excess acid. Why do you think this is the case? It is important not to add too much acid, because it may hydrolyse some of the lactose in the milk and reduce the yield.