Lab 1 Chm 412 - Recrystallization and Melting Point

CHM 412

ORGANIC CHEMISTRY

EXPERIMENT 2: RECRYSTALLIZATION AND MELTING POINT

Chemicals

- Acetanilide about 1-2 g

Apparatus  

1.        1 Erlenmeyer flask

2.        1 hot plate

3.        1 short stem/stemless gravity filter funnel

4.        1 beaker (100ml)

5.        1filter paper

6.        1 Buchner funnel

7.        1 Buchner flask

8.        1 rubber hoses

1. A vacuum pump
2. A retort stand
3. 1 watch glass
4. 3 melting-point capillary tubes
5. 1 long pieces of glass/plastic tube
6. A melting point temperature determining apparatus

Procedure

1. Impure acetanilide about 1-2 g was placed in a Erlenmeyer flask.
2. Heating of the water using hot plate until boiling was done and minimum amount of hot          

water was added to dissolve the acetanilide and soluble impurities while continuously         h        eating the mixture at the boiling point.

1. The hot water was added little by little until all the acetanilide dissolves.
2. As a precaution, do not continue to add the solvent in attempts to dissolve the insoluble         contaminants.
3. It was noted that the acetanilide was dissolve in hot water forming an oily layer. Hence,         boiling water was added enough to dissolve the oils.

1. The hot solution was filtered into a 100 ml sized beaker using a short stem or stemless                 gravity filter funnel and fluted filter paper. The clear filtrate was cooled gradually at room                 temperature and allowed the compound to crystallize. To crystallize even more compound                   the beaker was cooled in ice bath.
2. After 30 minutes the the crystal was collected in buchner funnel and the crystal was rinsed                 with not more than 20 ml ice cold water.
3. The crystal was transferred onto a watch glass and was dried in the oven.
4. To prepare a solid sample for a melting point determination, one of the end melting-point                 capillary was sealed using hot temperature and then the open end of the melting-point         capillary was pressed down on the sample so that the sample is forced up into the tube.
5. Then the tube was dropped into a long piece of glass tubing in upright position to knock                 down the sample to the closed end.
6. The capillary was introduced into a melting point temperature determining apparatus and         start heating. Lastly the sample was watched through the magnifier when its start to melts         and was noted the temperature range.

Diagrams

GRAVITATIONAL FILTRATION

[pic 1]

BUCHNER FILTRATION

[pic 2]

Data and Results:

Weight of acetanilide solid

Melting Results