SolutionsHow to Separate and Purify an Organic Compound
1. A suspicious melting point
A pure compound melts at 122 °C. A sample you have just synthesized melts between 115 °C and 119 °C. What does this tell you and what would you do?
The sample is impure: impurities lower the melting point and widen the melting range. It must be purified (for example, by crystallization) and its melting point measured again until a high value and a narrow range are obtained.
2. Non-toxic impurities
If an impurity is not toxic, why must it be removed from an active ingredient?
Because it alters the physical and chemical properties of the compound (melting point, solubility, density, reactivity) and therefore its behaviour in the medicine, and because it prevents us from knowing for certain what is being administered.