Separation of four components

The purpose of the experiment is to separate a mixture of three compounds of benzoic
acid, benzoin, and 1,4- dibromo benzene. Extraction and crystallization processes methods will
be employed as a method of obtaining pure forms of two of the three compounds in the mixture.
Diethyl ethene will be used as an organic solvent in the experiment.
Chemical Reactions

Figure 1 chemical reactions

Procedure
 Dissolve 0.5g of the mixture in diethyl ether
 Put the mixture in a separating funnel and add aqueous sodium hydroxide

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 Release any built-up gas in the separating gas by shaking the mixture and letting it
settle
 Collect the bottom layer in the separating funnel, leaving the top layer
 Add HCL to the collected solution and allow it to precipitate
 Use a vacuum filtration to remove the precipitate
 Collect the other remaining layer in a beaker and add hexane
 Use a vacuum filter to collect the crystals
 Add water to the crystals and heat the mixture of water and crystals to dissolve
the crystals.
 Once dissolved, cool to room temperature and cool on ice, then filter again using
a vacuum filter.
 Collect the crystals and test for mass and melting points
Data and Observation

The dissolving of the mixture in diethyl ether resulted in a clear solution of no color or
observable heat changes indicating no exothermic reactions took place. The addition of aqueous
sodium hydroxide to the mixture resulted in two layers being formed. The addition of food
coloring presented a clear indication of the presence of two layers. The addition of HCL led to
the formation of a white precipitate that settled down in the beaker when let to settle down.
Filtration of the mixture resulted in the collection of a liquid that was colorless.
The addition of hexene to the second layer resulted in the formation of crystals that were
colorless. The crystals dissolved in the water only when its temperature began rising. Cooling
and second filtration resulted in the formation of clear crystals that were collected from the
vacuum filter and a colorless solution.

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The first product crystals had an average melting point of 111.5 o C, while the second
product had a melting point of 129.3 o C. Spectroscopy was not done on the solids obtained, but
they all had a crystalline structure when dried up.

Calculations

Table 1 Quantity of experiment materials
Item Amount
Mixture 0.5g
Diethyl ether 2mL
NaOH 1M, 4mL
HCL 1M,2mL

% Yield benzoic acid =0.21/0.25 x 100% = 84%
%yield benzoin = 0.15/0.2 = 75%

Discussion

The mixture contains 50% benzoic acid, 40% benzoin, and 10% 1,4-dibromozene, which
was dissolved in an organic solvent of diethyl ether. The addition of aqueous sodium hydroxide
resulted in the formation of two layers. The above layer was an organic layer while the lower an
aqueous layer. The organic layer was the 40% benzoin and 10% 1,4- dibromo benzene, with the
aqueous layer being benzoic acid and sodium salts. The addition of the hydrochloric acid
resulted in a precipitate formation which, when filtered out, gave the formation of pure benzoic
acid. The addition of hexane to the organic layer will result in the formation of benzoin crystals.
Filtering the crystals out will result in the formation of a 1,4- dibromo benzene as the mother

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liquid. The lower yield percentages may have been a result of the errors in transferring the
contents into different containers where some of the mixtures may have been left behind the
solids were also dried up to observe the crystalline physical appearance that they portrayed.

Conclusion

The experiment was successful as two products out of the three in the mixture were
successfully separated and tested. The two products include the benzoic acid crystals and the
benzoin crystals. Errors may have occurred during the experiment that resulted in the lower yield
points as impurities in the mixture and products were also not accounted for