This experiment is from the official website of Jimei University

Operation method

Recrystallization and purification experiments

Principle

Meaning: the solid crude products separated from the organic synthesis reaction often contain unreacted raw materials, by-products and impurities, must be separated and purified, recrystallization is an important, commonly used separation method to separate and purify pure solid compounds. Scope of application: it is suitable for products and impurities with large differences in nature, the impurity content of the product is less than 5% of the system. Principle: the use of the components of the mixture in a solvent solubility or in the same solvent at different temperatures in different solubility and make them separate from each other.

Move

Purpose: Purification of crude acetanilide

Add 2 g of crude acetanilide and a measured amount of water to a 100 mL beaker and heat to boiling until the acetanilide dissolves (if it does not, add a small amount of hot water, stir and heat to near boiling to dissolve the acetanilide). Remove the beaker and cool slightly, then add a measured amount of activated carbon to the solution and boil for 5-10 minutes.

While still hot, the solution was filtered through a hot water funnel and fan-shaped filter paper and the filtrate was collected in a beaker. During filtration, both the hot water funnel and the solution should be kept warm over low heat to avoid cooling.

The filtrate is allowed to cool thoroughly, and when crystals precipitate, the crystals are drawn off and washed with a small amount of solvent (water).

The surface of the crystals was washed with a small amount of solvent (water), drained, and the product was removed and placed on a surface dish to air dry or dry, and tested for melting point and infrared spectroscopy.

Caveat

1. When decolorizing with activated carbon, do not add the activated carbon to a solution that is boiling.

2. The filter paper should not be larger than the bottom of the Brinell funnel.

3. When stopping the filtration pumping first remove the rubber tube connected between the filtration bottle and the pump, or open the piston on the safety bottle to the atmosphere, and then turn off the pump to prevent water from flowing back into the filtration bottle.

For more product details, please visit Aladdin Scientific website.

https://www.aladdinsci.com/