Separation and Purification of Organic Compounds

Abstract

The distillation process was successfully done because of the separation of water from the acetone. When the distillate was lighted with the matchstick it produced flame which indicates that there was more presence of acetone than water. When the sodium nitroprusside, sodium hydroxide and glacial acetic acid was added to the distillate, it turned to violet. This means that there is the presence of ketone.

Introduction

Distillation is the process heating a liquid until it boils, then condensing and collecting the resultant hot vapors.

Distillation is used to purify a compound by separating it from a non-volatile or less-volatile material and it is a commonly used method for purifying and separating mixtures of liquids into their individual components. As the mixture is heated, the temperature rises until it reaches the temperature of the lowest boiling substance in the mixture, while the other components of the mixture remain in their original phase in the mixture.

The resultant hot vapor passes into a condenser and is converted to the liquid, which is then collected in a receiver flask.

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The other components of the mixture remain in their original phase until the most volatile substance has all boiled off. Only then does the temperature of the gas phase rises again until it reaches the boiling point of a second component in the mixture.

The objective is to separate and purify organic compounds.

Experimental Procedure

A 50 mL of a mixture containing 25 mL of acetone and 25 mL of water was placed in a distilling flask.

Three pieces of porcelain chips was added to prevent bumping that was produced by a constant stream of bubbles which keeps the liquid in movement. The distillation set-up was prepared by the students. Before proceeding to the next step, the instructor must approved the said set-up.

It was heated with an electric hot plate and 5 mL of distillate was collected at 56oC and another 5 mL at 100oC. After that, 3 drops of distillate was placed in an evaporating dish and was ignited with lighted matchstick. On another evaporating dish, 3 drops of distillate was placed again and a drop of sodium nitroprusside, sodium hydroxide, and glacial acetic acid was added on to it.

Separation of Miscible Liquids

• A mixture containing 25 mL of acetone and 25 mL of water was placed in a distilling flask and 3 porcelain chips was added.
• A distillation set-up was prepared.
• Let the set-up be approved by the instructor. Then, do the next procedure.
• It was heated with an electric hot plate while collecting 5 mL of distillate at 56 degree Celsius and another 5mL at 100 degrees Celsius.
• B. Test for Completeness of Separation
• The drops of distillate was placed in an evaporating dish and was ignited with a lighted matchstick.
• A 1 drop of distillate was placed in an evaporating dish. A 5% of sodium nitroprusside, NaOH, glacial acetic acid was added. One drop each. There was a changed in the color.

Figure # 1: Schematic Diagram of the Procedure

Figure # 2: The Experimental Design
Results and Discussion

When acetone, water, and pocelain chips were placed in the distilling flask while heating, the acetone evaporated at 60oC and the water at 100oC. The distillation process was formed when the water vaporized and separated from the acetone. When the water was vaporized, the vapor is led in the condenser. Upon cooling, the water returned to the liquid form and run into a receiving container while the acetone remained on the other container. After putting three drops of distillate in the evaporating dish, it was ignited and it produced flame.

Therefore, there is more amount of acetone than water on the distillate. On another dry evaporating dish, three drops of distillate was placed again and 1 drop of 5% of sodium nitroprusside, 1 drop of 5% of sodium hydroxide and 1 drop of glacial acetic acid was added. The color turned into violet. It indicates the presence of ketone on the solution.

Conclusion

The acetone was distilled as the first fraction because it boiled before the water in the mixture, which resulted in collecting the entire acetone in the mixture before the water was boiled and collected. Fractional distillation did work because in the end, acetone was separated in a different beaker than water.

References

1. Lontoc, Betty Marges. Et.al. Laboratory Manual In Basic Organic Chemistry, 3rd edition, Centro Escolar University, 2004
2. http://swc2.hccs.edu/pahlavan/2423L7.pdf